Co-reporter:Huan-ling Wu, David H. Bremner, Hai-jun Wang, Jun-zi Wu, He-yu Li, Jian-rong Wu, Shi-wei Niu, Li-min Zhu
Materials Science and Engineering: C 2017 Volume 79(Volume 79) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.msec.2017.05.073
•Bacterial cellulose nanocrystals (BCNCs) with a highly oriented nanofibril bundle structure have been prepared.•A secondary hyperfine structure consisting of nanofibrils with diameters of just several nanometers has been investigated.•A novel strategy involving partial dissolution BC greatly enhanced the mechanical performance of the spun filaments.•A post-treatment process was utilized to remove residual solvents from the RBC/BC fibers to ensure biocompatibility.A high-strength regenerated bacterial cellulose (RBC)/bacterial cellulose (BC) microfilament of potential use as a biomaterial was successfully prepared via a wet spinning process. The BC not only consists of a 3-D network composed of nanofibers with a diameter of several hundred nanometers but also has a secondary structure consisting of highly oriented nanofibrils with a diameter ranging from a few nanometers to tens of nanometers which explains the reason for the high mechanical strength of BC. Furthermore, a strategy of partially dissolving BC was used and this greatly enhanced the mechanical performance of spun filament and a method called post-treatment was utilized to remove residual solvents from the RBC/BC filaments. A comparison of structure, properties, as well as cytocompatibility between BC nanofibers and RBC/BC microfilaments was achieved using morphology, mechanical properties, X-ray Diffraction (XRD) and an enzymatic hydrolysis assay. The RBC/BC microfilament has a uniform groove structure with a diameter of 50–60 μm and XRD indicated that the crystal form was transformed from cellulose Iα to cellulose IIII and the degree of crystallinity of RBC/BC (33.22%) was much lower than the original BC (60.29%). The enzymatic hydrolysis assay proved that the RBC/BC material was more easily degraded than BC. ICP detection indicated that the residual amount of lithium was 0.07 mg/g (w/w) and GC–MS analysis showed the residual amount of DMAc to be 8.51 μg/g (w/w) demonstrating that the post-treatment process is necessary and effective for removal of residual materials from the RBC/BC microfilaments. Also, a cell viability assay demonstrated that after post-treatment the RBC/BC filaments had good cytocompatibility.Download high-res image (207KB)Download full-size image
Co-reporter:Heyu Li, Gareth R. Williams, Junzi Wu, Haijun Wang, Xiaozhu Sun, Li-Min Zhu
Materials Science and Engineering: C 2017 Volume 79(Volume 79) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.msec.2017.04.058
•PNIPAAm was blended with PLCL and ciprofloxacin, and electrospun to form thermosensitive fibers.•The wettability of the fibers changed dramatically when the temperature was increased.•Ciprofloxacin could be released from the fibers gradually, and imparted them with antibacterial activity.•Fibroblasts could proliferate on the fibers, indicating good biocompatibility.•The fibers have very promising healing performance in vivo.In this work, we aimed to develop new materials to reduce the secondary injuries which can be imparted when replacing wound dressings. Electrospun fibers based on the thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAAm), poly(l-lactic acid-co-ɛ-caprolactone) (PLCL), and the antibiotic ciprofloxacin (CIF) were prepared. The water contact angle of fibers made from a blend of PNIPAAm and PLCL changed dramatically when the temperature was increased above 32 °C. Sustained release of CIF from the formulations was observed over > 200 h. Moreover, L929 fibroblasts could proliferate on the fibers, indicating their biocompatibility. The CIF-loaded fibers were found to have potent antibacterial activity against E. coli and S. aureus. In vivo tests on rats indicated that CIF-loaded thermosensitive fibers have enhanced healing performance compared to CIF-loaded PLCL fibers or a commercial gauze. Electrospun PNIPAAm/PLCL fibers loaded with CIF thus have great promise in the development of new wound dressing materials.Download high-res image (82KB)Download full-size image
Co-reporter:Heyu Li, Kailin Liu, Qingqing Sang, Gareth R. Williams, Junzi Wu, Haijun Wang, Jianrong Wu, Li-Min Zhu
Colloids and Surfaces B: Biointerfaces 2017 Volume 159(Volume 159) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.colsurfb.2017.07.058
•Thermosensitive PDEGMA was synthesized by free-radical polymerization.•PDEGMA and EC were blended and electrospun into nanofibers successfully.•The wettability of the EC/PDEGMA fibers changed as the temperature increased.•KET loaded-fibers showed different release behaviors at 25 and 37 °C.•PDEGMA/EC fibers were found to have good biocompatibility towards fibroblasts.In this study, the thermosensitive polymer poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA) was synthesized and electrospun into fibers by blending with ethyl cellulose (EC). Fibers were additionally prepared loaded with ketoprofen (KET) as a model drug. Smooth cylindrical fibers could generally be observed by electron microscopy, although there were some beads and fused fibers visible in the KET-loaded materials. KET was found to be amorphously distributed in the fibers on the basis of X-ray diffraction data. From water contact angle measurements, it was clear that the wettability of the EC/PDEGMA systems changed as the temperature increased, with the fibers becoming markedly more hydrophobic. In vitro drug release studies showed that KET was released over a prolonged period of time with the fibers having different profiles at 25 and 37 °C, reflecting their thermosensitive properties. Furthermore, the materials were found to have good biocompatibility towards L929 fibroblasts. Thus, the fibers prepared in this work have potential as smart stimuli-responsive drug delivery systems.Download high-res image (181KB)Download full-size image
Co-reporter:Yao Lv, Qixia Pan, S.W. Annie Bligh, Heyu Li, ... Li-Min Zhu
Journal of Pharmaceutical Sciences 2017 Volume 106, Issue 5(Volume 106, Issue 5) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.xphs.2016.12.031
In this work, a smart drug delivery system of core-sheath nanofiber is reported. The core-sheath nanofibers were prepared with thermoresponsive poly-(N-isopropylacrylamide) (as core) and hydrophobic ethyl cellulose (as sheath) by coaxial electrospinning. Analogous medicated fibers were prepared by loading with a model drug ketoprofen (KET). The fibers were cylindrical without phase separation and have visible core-sheath structure as shown by scanning and transmission electron microscopy. X-ray diffraction patterns demonstrated the drug with the amorphous physical form was present in the fiber matrix. Fourier transform infrared spectroscopy analysis was conducted, finding that there were significant intermolecular interactions between KET and the polymers. Water contact angle measurements proved that the core-sheath fibers from hydrophilic transformed into hydrophobic when the temperature reached the lower critical solution temperature. In vitro drug-release study of nanofibers with KET displayed that the coaxial nanofibers were able to synergistically combine the characteristics of the 2 polymers producing a temperature-sensitive drug delivery system with sustained-release properties. In addition, they were established to be nontoxic and suitable for cell growth. These findings show that the core-sheath nanofiber is a potential candidate for controlling drug delivery system.
Co-reporter:Heyu Li, Gareth R. Williams, Junzi Wu, Yao Lv, Xiaozhu Sun, Huanling Wu, Li-Min Zhu
International Journal of Pharmaceutics 2017 Volume 517, Issues 1–2(Issue 1) pp:
Publication Date(Web):30 January 2017
DOI:10.1016/j.ijpharm.2016.12.008
To obtain wound dressings which could be removed easily without secondary injuries, we prepared thermoresponsive electrospun fiber mats containing poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA). Blend fibers of PDEGMA and poly(l-lactic acid-co-ε-caprolactone) (P(LLA-CL) were fabricated via electrospinning, and analogous fibers containing the antibiotic ciprofloxacin (CIF) were also prepared. Smooth cylindrical fibers were obtained, albeit with a small amount of beading visible for the ciprofloxacin-loaded fibers. X-ray diffraction showed the drug to exist in the amorphous physical form post-electrospinning. The composite fibers showed distinct thermosensitive properties and gave sustained release of CIF over more than 160 h in vitro. The fibers could promote the proliferation of fibroblasts, and by varying the temperature cells could easily be attached to and detached from the fibers. Antibacterial tests demonstrated that fibers loaded with ciprofloxacin were effective in inhibiting the growth of E. coli and S. aureus. In vivo investigations on rats indicated that the composite PDEGMA/P(LLA-CL) fibers loaded with CIF had much more potent wound healing properties than a commercial gauze and CIF-loaded fibers made solely of P(LLA-CL). These results demonstrate the potential of PDEGMA/P(LLA-CL)/ciprofloxacin fibers as advanced wound dressing materials.Download high-res image (208KB)Download full-size image
Co-reporter:Qingqing Sang, Gareth R. Williams, Huanling Wu, Kailin Liu, Heyu Li, Li-Min Zhu
Materials Science and Engineering: C 2017 Volume 81(Volume 81) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.msec.2017.08.007
•Gelatin and poly(lactide-co-ε-caprolactone) fibers loaded with ciprofloxacin and sodium bicarbonate were prepared.•The hydrophilic gelatin/sodium bicarbonate fibers show pH-sensitive release, with more drug released at lower pH.•The poly(lactide-co-ε-caprolactone) fibers have no pH sensitivity, as a result of their hydrophobic nature.In this work, we report electrospun nanofibers made of model hydrophobic (poly(lactide-co-ε-caprolactone); PLCL) and hydrophilic (gelatin) polymers. We explored the effect on drug release of the incorporation of sodium bicarbonate (SB) into these fibers, using the potent antibacterial agent ciprofloxacin as a model drug. The fibers prepared are smooth and have relatively uniform diameters lying between ca. 600 and 850 nm. The presence of ciprofloxacin in the fibers was confirmed using IR spectroscopy. X-ray diffraction showed the drug to be incorporated into the fibers in the amorphous form. In vitro drug release studies revealed that, as expected, more rapid drug release was seen with gelatin fibers than those made of PLCL, and a greater final release percentage was obtained. The inclusion of SB in the gelatin fibers imparts them with pH sensitivity: gelatin/SB fibers showed faster release at pH 5 than pH 7.4, while fibers without SB gave the same release profiles at both pHs. The PLCL fibers have no pH sensitivity, even when SB was included, as a result of their hydrophobic structure precluding the ingress of solvent. In vitro cell culture studies showed that all the fibers are able to promote cell proliferation. The ciprofloxacin loaded fibers are effective in inhibiting Escherichia coli and Staphylococcus aureus growth in antibacterial tests. Thus, the gelatin-based fibers can be used as pH-responsive drug delivery systems, with potential applications for instance in the treatment of tumor resection sites. Should these become infected, the pH would drop, resulting in ciprofloxacin being released and the infection halted.
Co-reporter:Qixia Pan, Yao Lv, Gareth R. Williams, Lei Tao, Huihui Yang, Heyu Li, Limin Zhu
Carbohydrate Polymers 2016 Volume 151() pp:812-820
Publication Date(Web):20 October 2016
DOI:10.1016/j.carbpol.2016.06.024
•Graphene oxide was functionalized with carboxymethyl chitosan, fluorescein isothiocyanate, and lactobionic acid.•The resultant composite can be loaded with doxorubicin with high efficiency.•Doxorubicin release from the drug-loaded systems is highly pH-responsive.•The doxorubicin-loaded graphene oxide composite can target drug delivery to hepatic cells, and efficiently induce cell death.In this work, we report a targeted drug delivery system built by functionalizing graphene oxide (GO) with carboxymethyl chitosan (CMC), fluorescein isothiocyanate and lactobionic acid (LA). Analogous systems without LA were prepared as controls. Doxorubicin (DOX) was loaded onto the composites through adsorption. The release behavior from both the LA-functionalized and the LA-free material is markedly pH sensitive. The modified GOs have high biocompatibility with the liver cancer cell line SMMC-7721, but can induce cell death after 24 h incubation if loaded with DOX. Tests with shorter (2 h) incubation times were undertaken to investigate the selectivity of the GO composites: under these conditions, neither DOX-loaded system was found to be toxic to the non-cancerous L929 cell line, but the LA-containing composite showed the ability to selectively induce cell death in cancerous (SMMC-7721) cells while the LA-free analogue was inactive here also. These findings show that the modified GO materials are strong potential candidates for targeted anticancer drug delivery systems.
Co-reporter:Huihui Yang, David H. Bremner, Lei Tao, Heyu Li, Juan Hu, Limin Zhu
Carbohydrate Polymers 2016 Volume 135() pp:72-78
Publication Date(Web):1 January 2016
DOI:10.1016/j.carbpol.2015.08.058
•Graphene oxide with functionalized modification for cancer drug delivery.•High drug loading capacity.•pH-responsive drug release behavior.•Specifically target delivery and effectively cells inhibition.In order to enhance the efficiency and specificity of anticancer drug delivery and realize intelligently controlled release, a new drug carrier was developed. Graphene oxide (GO) was first modified with carboxymethyl chitosan (CMC), followed by conjugation of hyaluronic acid (HA) and fluorescein isothiocyanate (FI). The resulting GO–CMC–FI–HA conjugate was characterized and used as a carrier to encapsulate the anticancer drug doxorubicin (DOX) to study in vitro release behavior. The drug loading capacity is as high as 95% and the drug release rate under tumor cell microenvironment of pH 5.8 is significantly higher than that under physiological conditions of pH 7.4. Cell uptake studies show that the GO–CMC–FI–HA/DOX complex can specifically target cancer cells, which are over-expressing CD44 receptors and effectively inhibit their growth. The above results suggest that the functionalized graphene-based material has potential applications for targeted delivery and controlled release of anticancer drugs.
Co-reporter:Yao Lv, Lei Tao, S.W. Annie Bligh, Huihui Yang, Qixia Pan, Limin Zhu
Materials Science and Engineering: C 2016 Volume 59() pp:652-660
Publication Date(Web):1 February 2016
DOI:10.1016/j.msec.2015.10.065
•Graphene oxide with functionalized modification for cancer drug delivery•High drug loading capacity•pH-responsive drug release behavior•Specifically target delivery and effectively cell inhibitionWe have synthesized a new multifunctional graphene oxide as a drug carrier targeting to hepatocarcinoma cells. Surface modified graphene oxide with polyethyleneimine (PEI) sequentially derivatised with fluorescein isothiocyanate (FI) and polyethylene glycol (PEG)-linked lactobionic acid (LA), and acetylation of remaining terminal amines of the PEI produced a new multifunctional graphene oxide drug carrier (GO/PEI.Ac-FI-PEG-LA). Doxorubicin (DOX), an anticancer drug, was encapsulated in GO/PEI.Ac-FI-PEG-LA to give GO/PEI.Ac-FI-PEG-LA/DOX, with a drug loading percentage of 85%. We showed that both GO/PEI.Ac-FI-PEG-LA and GO/PEI.Ac-FI-PEG-LA/DOX were water soluble and stable between pH 5.0 and 9.0. In vitro release studies indicated that the release rate of DOX from GO/PEI.Ac-FI-PEG-LA/DOX complexes were significantly higher at pH 5.8 than that of the physiological pH. Another important feature of this carrier is its good cell viability in the tested concentration range (0‐4 μM), and the GO/PEI.Ac-FI-PEG-LA/DOX can specifically target cancer cells overexpressing asialoglycoprotein (ASGPR) receptors and exert growth inhibition effect to the cancer cells. The enhanced target specificity and the substantial improvement in pH responsive controlled release have made this new carrier a potential choice for non-covalent encapsulation of drugs in GO, and a delivery system for cancer therapy.
Co-reporter:Huan-ling Wu, David H. Bremner, He-yu Li, Qi-quan Shi, Jun-zi Wu, Rui-qiu Xiao, Li-min Zhu
Materials Science and Engineering: C 2016 Volume 62() pp:702-709
Publication Date(Web):1 May 2016
DOI:10.1016/j.msec.2016.02.026
•Based on a wet spinning technique, a series of filaments which can be used as biomaterial have been successfully prepared.•The drug loading filaments showed good mechanical properties and could be woven into fabrics.•The Cur/Vit. E Ac/PAN filaments exhibited a unique microvoid cross-sectional morphology.•No cytotoxicity was found up to 5% and 10% respectively of the theoretical drug loading content of curcumin and Vit. E Ac.Wet spun microfibers have great potential in the design of multifunctional controlled release materials. Curcumin (Cur) and vitamin E acetate (Vit. E Ac) were used as a model drug system to evaluate the potential application of the drug-loaded microfiber system for enhanced delivery. The drugs and polyacrylonitrile (PAN) were blended together and spun to produce the target drug-loaded microfiber using an improved wet-spinning method and then the microfibers were successfully woven into fabrics. Morphological, mechanical properties, thermal behavior, drug release performance characteristics, and cytocompatibility were determined. The drug-loaded microfiber had a lobed “kidney” shape with a height of 50–100 μm and width of 100–200 μm. The addition of Cur and Vit. E Ac had a great influence on the surface and cross section structure of the microfiber, leading to a rough surface having microvoids. X-ray diffraction and Fourier transform infrared spectroscopy indicated that the drugs were successfully encapsulated and dispersed evenly in the microfilament fiber. After drug loading, the mechanical performance of the microfilament changed, with the breaking strength improved slightly, but the tensile elongation increased significantly. Thermogravimetric results showed that the drug load had no apparent adverse effect on the thermal properties of the microfibers. However, drug release from the fiber, as determined through in-vitro experiments, is relatively low and this property is maintained over time. Furthermore, in-vitro cytocompatibility testing showed that no cytotoxicity on the L929 cells was found up to 5% and 10% respectively of the theoretical drug loading content (TDLC) of curcumin and vitamin E acetate. This study provides reference data to aid the development of multifunctional textiles and to explore their use in the biomedical material field.
Co-reporter:Xiao Gong, Christopher Branford-White, Lei Tao, Shubai Li, Jing Quan, Huali Nie, Limin Zhu
Materials Science and Engineering: C 2016 Volume 58() pp:478-486
Publication Date(Web):1 January 2016
DOI:10.1016/j.msec.2015.08.059
•A facile, time-saving approach to assemble Fomc-FF composite hydrogels was designed.•Hydrogel structures including nanowires, layered films and honeycombs can be controlled.•The role of SA in the Fmoc-FF/SA composite hydrogel was further clarified.Dipeptides and their derivatives have attracted tremendous attention owning to their excellent abilities of self-assemble assembling into various structures which have great potentials for applications in biology and/or nanotechnology. In the present study, we dedicate to fabricate a rigid and structure controllable Fmoc-FF/SA composite hydrogel. We found that the modified dipeptide, fluorenyl-9-methoxycarbonyl (Fmoc)-diphenylalanine (Phe-Phe) can self-assemble into rigid hydrogels with structures of nanowires, layered thin films or honeycombs as the change of sodium alginate (SA) concentration. Meanwhile, CD-spectroscopy demonstrated that SA appeared to control the process, but it did not change the arrangement of the Fmoc-FF peptide. Our results demonstrated that the formed hydrogel showed physical and chemical stability as well as possessing good biocompatibility. Rheological measurements showed that the addition of SA could improve the stability of the hydrogel. Cell viability assay revealed that the Fmoc-FF and Fmoc-FF/SA hydrogels are both beneficial for cell proliferation in-vitro. Our results indicated that the fabricated Fmoc-FF/SA composite hydrogels could be used in tissue engineering and drug delivery in the future.
Co-reporter:Huan-Ling Wu;Xiao-Xiao Hou;Christopher Branford-White;Xiao-Zhu Sun;Lei Tao;Syeda Um-I-Zahra
Journal of Applied Polymer Science 2015 Volume 132( Issue 40) pp:
Publication Date(Web):
DOI:10.1002/app.42618
ABSTRACT
Calcium carbonate (CaCO3)/alginate inorganic–organic hybrid particles were synthesized and deposited on to the surface of cotton fabrics with a novel one-step procedure. The effects of the Ca2+/CO32−/alginate molar ratio on the cotton matrix were investigated. The optimization of the process resulted in a regular shaped hybrid microparticles, and scanning electron microscopy revealed that the particles were uniformly distributed on the surface of the fibers. Dynamic light scattering showed that the particles were about 2 μm in diameter. Moreover, transmission electron microscopy images demonstrated that the core–shell structure of the particles existed along with CaCO3 evenly enfolded into the alginate layer. An X-ray diffraction pattern displayed that the alginate/CaCO3 hybrid microparticles were a mixture of calcite and vaterite crystal. Fourier transform infrared spectroscopy indicated that CaCO3/alginate hybrid particles formed in situ were the only deposited materials. The thermogravimetric analysis curve indicated a certain mass ratio of the alginate and CaCO3 in the hybrid particles. Furthermore, the drug-loading and drug-release properties of the hybrid microspheres were studied, and the results show that the water-soluble diclofenac sodium could be effectively loaded in the hybrid microparticles and the drug release could be effectively sustained. Finally, both of the microparticles and modified fabrics had good cytocompatibility. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42618.
Co-reporter:Zhaoqiang Ding, S.W. Annie Bligh, Lei Tao, Jing Quan, Huali Nie, Limin Zhu, Xiao Gong
Materials Science and Engineering: C 2015 Volume 48() pp:469-479
Publication Date(Web):1 March 2015
DOI:10.1016/j.msec.2014.12.032
•A novel fluorescent biomimetic sensor based on MWCNT-QDs was designed.•The sensor exhibited a fast mass-transfer speed with a response time of 25 min.•The sensor possessed a highly selective recognition to BSA.A novel molecularly imprinted optosensing material based on multi-walled carbon nanotube-quantum dots (MWCNT-QDs) has been designed and synthesized for its high selectivity, sensitivity and specificity in the recognition of a target protein bovine serum albumin (BSA). Molecularly imprinted polymer coated MWCNT-QDs using BSA as the template (BMIP-coated MWCNT-QDs) exhibits a fast mass-transfer speed with a response time of 25 min. It is found that the BSA as a target protein can significantly quench the luminescence of BMIP-coated MWCNT-QDs in a concentration-dependent manner that is best described by a Stern–Volmer equation. The KSV for BSA is much higher than bovine hemoglobin and lysozyme, implying a highly selective recognition of the BMIP-coated MWCNT-QDs to BSA. Under optimal conditions, the relative fluorescence intensity of BMIP-coated MWCNT-QDs decreases linearly with the increasing target protein BSA in the concentration range of 5.0 × 10−7–35.0 × 10−7 M with a detection limit of 80 nM.
Co-reporter:Mu-Ru Xu, Meng Shi, David H. Bremner, Kan Sun, Hua-Li Nie, Jing Quan, Li-Min Zhu
Colloids and Surfaces B: Biointerfaces 2015 Volume 135() pp:209-216
Publication Date(Web):1 November 2015
DOI:10.1016/j.colsurfb.2015.07.041
•Thermoresponsive double hydrophilic copolymers are one of the most important candidates of biomaterials and have capability of reversible micellization and dissociation responding to the change of temperature.•We prepared thermoresponsive double-hydrophilic glycopolymers (TDHG) nanofibers for the first time by a free radical copolymerization and electrospinning method.•The cytotoxicity of TDHG nanofibers were investigated for their potential as drug carriers in controlled drug delivery for targeting of hepatic cells.The thermoresponsive double-hydrophilic glycopolymer (DHG), Poly (6-O-vinyl-nonanedioyl-d-galactose-co-N-vinylcaprolactam) (P(OVNG-co-NVCL)) was synthesized via a chemo-enzymatic process and a free radical copolymerization and the resulting nanofibers were fabricated using an electrospinning process. The desired lower critical solution temperature (LCST) between 32 and 40 °C of the DHG polymers was achieved by adjusting the molar fraction of galactose monomer in the copolymers during the synthesis. The thermoresponsive DHG polymers were found to have good cytocompatibility with Hela cells as determined by the MTT assay, and special recognition of the protein peanut agglutinin (PNA). The drug release properties of these newly designed thermoresponsive DHG P(OVNG-co-NVCL) nanofibers are temperature regulated, can target specific proteins and have the potential application in the field of sustained drug release.Cluster-glycoside effect of PNA-FITC and P(OVNG-co-NVCL).
Co-reporter:Xiao-Zhu Sun;Christopher Branford-White
Journal of Sol-Gel Science and Technology 2015 Volume 74( Issue 3) pp:641-649
Publication Date(Web):2015 June
DOI:10.1007/s10971-015-3643-2
We report that halochromic textiles are promising sensory system for measuring changes in pH. The system is easy to manage and process. In this study a universal pH sensitive textile was developed using a sol–gel method, which recorded pH by displaying unique color. The indicators incorporated in the sol system are different and are dependent on the substrate used. Samples demonstrated sufficient stability against leaching on account of the hybrid structure generated in the silicon matrix. Moreover, the interaction between the gel matrix and indicators depended on the charges and size of the guest molecules, and the tensile strength of cotton was enhanced by the gel film. The present research opens up new avenues to develop sensors based on textiles which have the potential to be employed in wider industrial applications.
Co-reporter:Lei Wang, Gareth R. Williams, Hua-li Nie, Jing Quan and Li-min Zhu
Polymer Chemistry 2014 vol. 5(Issue 8) pp:3009-3017
Publication Date(Web):07 Jan 2014
DOI:10.1039/C3PY01332D
The thermoresponsive glycopolymers poly-(N-isopropylacrylamide-co-6-O-vinyladipoyl-D-glucose) (poly-NIPAM-co-OVDG; PND) and poly-(N-isopropylacrylamide-co-6-O-vinylazelaicoyl-D-glucose) (poly-NIPAM-co-OVZG; PNZ) have been prepared by a free radical polymerization process, and subsequently processed into blended fibers with poly-L-lactide-co-ε-caprolactone (PLCL) using electrospinning. The fibers were found to inhibit the non-specific adsorption of bovine serum albumin onto their surfaces, but could selectively recognize the lectin Concanavalin A (Con A). The adsorbed Con A can easily be desorbed with a glucose solution. The synthesized fibers were found to have excellent biocompatibility with HeLa cells using the MTT assay, but when loaded with Con A could be used to induce death in the cell population.
Co-reporter:Kan Sun, S. W. Annie Bligh, Hua-li Nie, Jing Quan and Li-min Zhu
RSC Advances 2014 vol. 4(Issue 66) pp:34912-34921
Publication Date(Web):01 Aug 2014
DOI:10.1039/C4RA04874A
Thermoresponsive double hydrophilic block glycopolymer poly(N-isopropylacrylamide-co-6-O-vinyladipoyl-D-glucose)-b-poly(N-isopropylacrylamide) (P(NIPAm-co-OVAG)-b-PNIPAm) was prepared by a combination of enzymatic synthesis and reversible addition-fragment chain transfer (RAFT) polymerization protocols using P(NIPAm-co-OVAG) as a macro-RAFT agent. All the precisely synthesized glycopolymers were characterized by nuclear magnetic resonance spectroscopy and gel permeation chromatography. Detections using laser light scattering and transmission electron microscopy revealed that the block glycopolymer was able to self-assemble into micelles with various sizes and sphere morphologies in aqueous solutions. The glucose pendants in the glycopolymers had obvious interaction with lectin, concanavalin A (Con A), and their capacity of interaction with Con A was controlled by the number of glucose units in the glycopolymers. The block glycopolymer micelles have excellent biocompatibility with pig iliac endothelial cells using the MTT assay, however the glycopolymer–Con A micelles could be used to induce apoptosis in human hepatoma SMMC-7721 cells.
Co-reporter:Zhaoqiang Ding, Yanping Zhu, Christopher Branford-White, Kan Sun, Syeda Um-i-Zahra, Jing Quan, Huali Nie, Limin Zhu
Materials Letters 2014 Volume 128() pp:310-313
Publication Date(Web):1 August 2014
DOI:10.1016/j.matlet.2014.04.165
•MWCNTs-COOH/PVA nanofiber mats were fabricated using electrospinning.•A transparent and conductive film was generated by self-assembly when the nanofiber mats were immersed in water.•The mechanical properties, electrical conduction and optical transparency of the composite films were studied.•The potential mechanisms governing the transparent conductive composite films from nanofiber mats were raised.Carboxylated multi-walled carbon nanotubes (MWCNTs-COOH)/poly(vinyl alcohol) (PVA) nanofiber mats were fabricated using electrospinning. Due to the hydrophilic and swelling properties of the nanofibers, a transparent film was generated by self-assembly when the nanofibers were immersed in water. The composite film with MWCNTs-COOH fraction 8.76 wt% exhibits electrical conductivity of 1.8×10−4 S/cm, while maintaining 166.98 MPa tensile strength and 61% optical transmittance. The method reported here is simple and feasible for large scale production of CNTs based composite films.
Co-reporter:Heng-huan Song, Xiao Gong, Gareth R. Williams, Jing Quan, Hua-li Nie, Li-min Zhu, Er-long Nan, Ming Shao
Materials Research Bulletin 2014 53() pp: 280-289
Publication Date(Web):
DOI:10.1016/j.materresbull.2014.02.026
Co-reporter:Syeda Um-i-Zahra;Xia Xia Shen;Heyu Li;Limin Zhu
Journal of Polymer Research 2014 Volume 21( Issue 12) pp:
Publication Date(Web):2014 December
DOI:10.1007/s10965-014-0602-5
Sustained release cellulose acetate (CA) and ethyl cellulose (EC) polymer blend nanofibers loaded with ketoprofen (KET) were successfully prepared by electrospinning. Successful fiber formation has been investigated by using two different binary solvent systems, i.e., acetic acid + distilled water (2:1 v/v) and acetone + N,N-DMAc + ethanol (2:1:1 v/v). Scanning electron microscopy (SEM) images showed that morphological features gradually change as the ratio of both polymers change. Nanofiber diameter also decreases as the CA content is increased in the polymer blend solution from 77.25 ±27 to 72.39 ±30 nm. Drug release profiles were evaluated by in-vitro drug release experiments. Drug release follows a pseudo-Fickian behavior of diffusion and shows a sustained release mechanism. Nanofibers containing more CA show greater controlled release capacity as compared to EC. X-ray diffraction (XRD) patterns of CA and EC polymer blend nanocomposites show that crystalline ketoprofen has changed into an amorphous state. Fourier transform Infrared (FTIR) analysis indicates hydrogen bonding occurs between the drug and the polymer, accounting for molecular integration of the two components. The thermal stability of the prepared polymer blend was also studied using thermo-gravimetric analysis (TGA). A polymer blend sustained release drug delivery system prepared by electrospinning make it possible to fabricate other novel drug releasing systems.
Co-reporter:Ran Wei;Cheng-Cheng Jin;Jing Quan;Hua-li Nie
Biopolymers 2014 Volume 101( Issue 3) pp:272-278
Publication Date(Web):
DOI:10.1002/bip.22346
ABSTRACT
A novel heptapeptide comprising Ile-Gln-Ser-Pro-His-Phe-Phe (IQSPHFF) identified and found to undergo self-assembly into microparticles in solution. To understand the effects of ultraviolet (UV) irradiation on the self-assembly process, IQSPHFF solutions were exposed to the UV light of 365 nm at room temperature. This exposure was found to have a profound effect on the morphology of the self-assembled aggregates, converting the microparticles to nanorod shapes. Circular dichroism and FTIR studies indicated distinct structural differences in the arrangements of the peptide moieties before and after UV irradiation. However, Mass spectrum analysis and high performance liquid chromatography of the peptide molecules before and after UV irradiation demonstrated that the chemical structure of IQSPHFF was not changed. UV–visible spectroscopy and fluorescence spectroscopy studies showed that the absorption peak both increased after UV irradiation. Overall, our data show that the heptapeptide with UV-responsive properties. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 272–278, 2014.
Co-reporter:Jing Quan, Zhongqing Liu, Christopher Branford-White, Huali Nie, Limin Zhu
Colloids and Surfaces B: Biointerfaces 2014 Volume 121() pp:417-424
Publication Date(Web):1 September 2014
DOI:10.1016/j.colsurfb.2014.06.030
•A novel glycopolymer is prepared by water phase precipitation polymerization.•The glycopolymer is made into composite nanofibers by electrospun with MWCNTs.•The hydrophilicity of glycopolymer nanofibers is significantly improved.•Immobilized catalase exhibits significantly higher thermal stability and durability.Glycopolymer (poly(AN-co-OVSEG))/MWCNTs (multiwalled carbon nanotubes) composite nanofibers are fabricated using a facile approach combining enzymatic synthesis, radical polymerization and electrospinning. The structure of the glycopolymer was confirmed by FT-IR and 1H NMR. Poly(AN-co-OVSEG)/MWCNTs composite nanofibers were prepared using electrospinning and characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The hydrophilic properties of the composite nanofibers surfaces were increased since the contact angle of poly(AN-co-OVSEG)/MWCNTs composite was reduced from 65.5° to 37° compared to (PAN). As an enzymatic model catalase (CAT) was loaded (ca. 55.0 mg/g) to the poly(AN-co-OVSEG)/MWCNTs nanofibers. The optimum temperature for poly(AN-co-OVSEG)/MWCNTs nanofibers increased from 25 °C to 45 °C compared to free CAT. The covalently immobilized enzymes conjugate exhibited 60% activity at 60 °C, while the free enzyme was entirely inactivity after 5 min heat treatment. The immobilized CAT retained 70% of its initial activity after 5 cycles of decomposition of hydrogen peroxide.
Co-reporter:Shao-Feng Lou, Lei Wang, Gareth R. Williams, Huali Nie, Jing Quan, Limin Zhu
Colloids and Surfaces B: Biointerfaces 2014 Volume 113() pp:368-374
Publication Date(Web):1 January 2014
DOI:10.1016/j.colsurfb.2013.08.045
•Novel galactose-functionalised thermoresponsive injectable microgels were synthesized.•The LCST, VPTT and Tsol–gel of the materials could be controlled by varying the monomer ratios.•The microgels were loaded with the model protein bovine serum albumin (BSA), and in vitro release studies showed that the BSA release kinetics depend upon the temperature and copolymer composition.Novel galactose functionalized thermoresponsive injectable microgels, poly(N-isopropylacrylamide-co-6-O-vinyladipoyl-d-galactose) P(NIPAAm-co-VAGA), have been fabricated using a combination of enzymatic transesterification and emulsion copolymerization. The microgels exhibit reversible temperature-responsive behavior, which can be tuned by varying the monomer feed ratio. The lower critical solution temperatures (LCSTs) of the materials are close to body temperature and can result in a rapid thermal gelation at 37 °C. Field emission scanning electron microscopy showed the resultant microgels to have porous structures, and dynamic light scattering experiments indicated a dramatic reduction in particle size as solutions of the polymers are heated through the LCST. The polymers can be loaded with protein (bovine serum albumin; BSA), and in vitro studies showed that the BSA release kinetics depend upon the temperature and copolymer composition. Microgels based on P(NIPAAm-co-VAGA) could hence serve as candidates for site-specific sustained release drug delivery systems.
Co-reporter:Xiao-Zhu Sun, Gareth R. Williams, Xiao-Xiao Hou, Li-Min Zhu
Carbohydrate Polymers 2013 Volume 94(Issue 1) pp:147-153
Publication Date(Web):15 April 2013
DOI:10.1016/j.carbpol.2012.12.064
Polyvinyl alcohol (PVA) nanofibers loaded with curcumin or its β-cyclodextrin (CD) inclusion complex were successfully prepared using an electrospinning process. The influence of curcumin or CD–curcumin complex content on fiber formation and quality was investigated. X-ray diffraction and differential scanning calorimetry analyses of the fibers, together with electron microscope evidence, demonstrated that curcumin is likely to be present as crystalline aggregates in the fibers, while its CD complex is more evenly distributed. 1H NMR analysis indicated that the chemical structure of curcumin was preserved during the electrospinning process. Thermogravimetric analysis demonstrated that inclusion into nanofibers enhanced the thermal stability of curcumin. In vitro dissolution tests showed that the drug release profiles of the PVA/curcumin and PVA/complex fibers were different, with release from the latter occurring more rapidly. Release from both fiber types was found to be largely governed by a diffusion-controlled mechanism; two sequential stages for drug release were observed.Highlights► Nanofibers containing curcumin or its CD complex were prepared by electrospinning. ► The CD complexes showed a more even distribution in fibers than curcumin alone. ► Two sequential stages for drug release were observed with both fiber types. ► Release was found to be largely governed by a diffusion-controlled mechanism.
Co-reporter:Jing Quan;Chengyao Wu;Gareth R. Williams;Christopher J. Branford-White;Huali Nie;Limin Zhu
Journal of Applied Polymer Science 2013 Volume 130( Issue 3) pp:1570-1577
Publication Date(Web):
DOI:10.1002/app.39309
ABSTRACT
A facile and efficient protocol for the preparation of nanofibers incorporating polymeric ketoprofen prodrugs and polyvinylpyrrolidone was developed. Polymeric ketoprofen prodrugs were constructed by a two-step chemo-enzymatic synthetic route, and nanofibers prepared by electrospinning from dimethylformamide/ethanol (1 : 1, v/v) solutions. The morphological characteristics of the fibers were influenced by the concentration of active agent in the spinning solution; average diameters varied from 196 to 370 nm. In vitro release studies indicated that the ketoprofen release rate from the electrospun fibers was significantly higher than that from the pure polymeric prodrugs. Cumulative drug release from the electrospun fibers reached 40–70% after 3 h and 75–100% after 12 h, while the pure polymeric prodrug released only 7–9% of the active agent over 12 h. Functional nanofibers incorporating polymeric prodrugs therefore comprise potentially effective drug delivery systems for sustained release. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1570–1577, 2013
Co-reporter:Er-long Nan, Gareth R. Williams, Heng-huan Song, Jing Quan, Hua-li Nie, and Li-min Zhu
Journal of Chemical & Engineering Data 2013 Volume 58(Issue 12) pp:3314-3319
Publication Date(Web):October 31, 2013
DOI:10.1021/je400364b
In this paper, the liquid–liquid–solid triple-phase data of some aqueous two-phase systems (ATPSs) containing hydrophilic organic solvents (HOS) and simple salts were explored. The systems studied comprise aqueous solutions containing ethanol, 1-propanol, 2-propanol, or acetone with (NH4)2SO4 and solutions containing 1-propanol with (NH4)2SO4, NaCl, or KCl. The Gibbs phase rule predicts that there is a linear relationship existing at such a triple-phase boundary. The linear liquid–liquid–solid boundaries were determined, and the effects of temperature, solvent, and salt on the boundary were investigated. The tie line length (TLL) of the systems distributed on the triple-phase boundary was invariant. Phase equilibrium experiments determined that the average TLL of ethanol–(NH4)2SO4 ATPSs at 298.15 K was 62.93 % with a standard deviation of 2.13 %. The linear liquid–liquid–solid triple-phase boundary was used to elucidate the two-phase region and determine the content of organic solvent or salt in an unknown sample. These results increase our understanding of HOS–salt–water aqueous two phase system (ATPS) and will be useful for those looking to develop new systems for separation science.
Co-reporter:Pei-pei Zhang, Bin Wang, Gareth R. Williams, Christopher Branford-White, Jing Quan, Hua-li Nie, Li-min Zhu
Materials Research Bulletin 2013 48(9) pp: 3058-3064
Publication Date(Web):
DOI:10.1016/j.materresbull.2013.04.052
Co-reporter:Bin Wang;Pei-pei Zhang;Gareth R. Williams
Journal of Materials Science 2013 Volume 48( Issue 11) pp:3991-3998
Publication Date(Web):2013 June
DOI:10.1007/s10853-013-7208-x
Composite non-woven mats of poly(vinyl pyrrolidone) (PVP), chitosan, and Fe3O4 were successfully fabricated using coaxial-electrospinning technique with PVP/chitosan as the shell and PVP/Fe3O4 as the core. Because of the templating and confinement properties of the nanofibers, magnetic chitosan nanoparticles (MCNPs) could be spontaneously formed through molecular self-assembly when the composite fibers were dissolved on treatment with acetum solution. By changing the weight ratio of Fe3O4:chitosan, the size of the MCNPs could be varied. The morphology, chemical composition, and magnetic characteristics of composite particles were characterized by means of scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and vibrating sample magnetometer. Experimental results indicated that the composite particles were super-paramagnetic with sizes in the range of 15–40 nm. This facile and new synthesis route comprises a convenient strategy to generate composite particles and should be broadly applicable to a wide range of systems, serving as a platform for the facile development of novel composite materials.
Co-reporter:Shao-Feng Lou, Hua Zhang, Gareth R. Williams, Christopher Branford-White, Hua-Li Nie, Jing Quan, Li-Min Zhu
Colloids and Surfaces B: Biointerfaces 2013 Volume 105() pp:180-186
Publication Date(Web):1 May 2013
DOI:10.1016/j.colsurfb.2012.12.012
Novel double-hydrophilic thermosensitive statistical glycopolymers, poly(N-isopropylacrylamide-co-6-O-vinyladipoyl-d-glucose), were fabricated using a chemoenzymatic process and free radical copolymerization. The structures of the glycopolymers were confirmed by 1H and 13C NMR, and their molar mass distributions determined by gel permeation chromatography. UV–vis spectroscopy data showed that the polymers exhibited reproducible temperature-responsive behavior. The self-assembly and critical aggregation concentration was verified by fluorescence spectroscopy with pyrene acting as a hydrophobic probe. Measurements by laser light scattering and transmission electron microscopy revealed that the glycopolymers were able to self-assemble into aggregates with varying particle sizes and morphologies in aqueous solutions.Graphical abstractHighlights► Novel thermoresponsive glucose-functionalised double hydrophilic copolymers were synthesised. ► The LCST of the copolymer solution could be controlled by varying the monomer ratios. ► The copolymers formed large and loose structures at low temperatures and compact spherical aggregates above the LCST.
Co-reporter:Yuan-Qing Ling, Hua-Li Nie, Christopher Brandford-White, Gareth R. Williams, Li-Min Zhu
Colloids and Surfaces B: Biointerfaces 2012 Volume 94() pp:281-287
Publication Date(Web):1 June 2012
DOI:10.1016/j.colsurfb.2012.02.004
This investigation involves the metal chelate affinity precipitation of bovine serum albumin (BSA) using a copper ion loaded thermo-sensitive copolymer. The copolymer of N-vinylcaprolactam with methacrylic acid PNVCL-co-MAA was synthesized by free radical polymerization in aqueous solution, and Cu(II) ions were attached to provide affinity properties for BSA. A maximum loading of 48.1 mg Cu2+ per gram of polymer was attained. The influence of pH, temperature, BSA and NaCl concentrations on BSA precipitation and of pH, ethylenediaminetetraacetic acid (EDTA) and NaCl concentrations on elution were systematically probed. The optimum conditions for BSA precipitation occurred when pH, temperature and BSA concentration were 6.0, 10 °C and 1.0 mg/ml, respectively and the most favorable elution conditions were at pH 4.0, with 0.2 M NaCl and 0.06 M EDTA. The maximum amounts of BSA precipitation and elution were 37.5 and 33.7 mg BSA/g polymer, respectively. It proved possible to perform multiple precipitation/elution cycles with a minimal loss of polymer efficacy. The results show that PNVCL-co-MAA is a suitable matrix for the purification of target proteins from unfractionated materials.Graphical abstractHighlights► Cu(II) was attached to provide affinity properties to thermo-sensitive polymer. ► Cation-loaded copolymer was employed as affinity macroligand. ► Thermo-sensitive macroligand was used for adsorption and elution of protein. ► Precipitation was induced by temperature after protein adsorption.
Co-reporter:Deng-Guang Yu, Li-Min Zhu, S. W. Annie Bligh, Christopher Branford-White and Kenneth N. White
Chemical Communications 2011 vol. 47(Issue 4) pp:1216-1218
Publication Date(Web):24 Nov 2010
DOI:10.1039/C0CC03521A
We show that coaxial electrospinning using organic solvent as the sheath fluid is a viable way to produce tailor-made nanofibers composed of polyvinylpyrrolidine, tristearic and naproxen. Self-assembled hybrid nanoparticles are generated from the composite nanofibers under aqueous conditions and particle size has a linear relationship with fiber diameter.
Co-reporter:Deng-Guang Yu, Christopher Branford-White, Gareth R. Williams, S. W. Annie Bligh, Kenneth White, Li-Min Zhu and Nicholas P. Chatterton
Soft Matter 2011 vol. 7(Issue 18) pp:8239-8247
Publication Date(Web):03 Aug 2011
DOI:10.1039/C1SM05961K
Amphiphilic nanofibers composed of the hydrophilic polymer polyvinylpyrrolidone K60 (PVP) and soybean lecithin were fabricated using an electrospinning process. As a result of the templating and confinement properties of the nanofibers, phosphatidyl choline (PC) liposomes were spontaneously formed through molecular self-assembly when the fibers were added to water. The sizes of the self-assembled liposomes could be manipulated by varying the content of PC in the nanofibers (over the range 9.1–33.3% (w/w) in the present study). The influence of PC on nanofiber formation, and a possible mechanism of templated liposome formation are discussed. This facile and convenient strategy for manipulating molecular self-assembly to synthesize liposomes provides a versatile new approach for the development of novel drug delivery systems and biomaterials.
Co-reporter:Liqiang Tian, Huali Nie, Nicholas P. Chatterton, Christopher J. Branford-White, Yiping Qiu, Limin Zhu
Applied Surface Science 2011 Volume 257(Issue 16) pp:7113-7118
Publication Date(Web):1 June 2011
DOI:10.1016/j.apsusc.2011.03.064
Abstract
The influence of atmospheric pressure plasma jet (APPJ) treatment on the hydrophilicity of grey cotton knitted fabric (GCKF) was investigated. For comparison, specimens which had undergone different treatments were tested by contact angle measurement, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) and X-ray diffraction (XRD). The results imply that helium/oxygen APPJ could improve the hydrophilicity of GCKF by modifying the surface properties. In addition, combining dewaxing processes with He/O2 APPJ treatment was found to tremendously improve the hydrophilicity of GCKF. The mechanism of this was also confirmed by Ruthenium Red staining which showed most of pectic substances inside the cotton fiber existed beneath the waxy layer and on top of the cellulose microfibril.
Co-reporter:Xiao-Mei Wu, Christopher J. Branford-White, Deng-Guang Yu, Nicholas P. Chatterton, Li-Min Zhu
Colloids and Surfaces B: Biointerfaces 2011 Volume 82(Issue 1) pp:247-252
Publication Date(Web):1 January 2011
DOI:10.1016/j.colsurfb.2010.08.049
Magnesium l-ascorbic acid 2-phosphate (MAAP) and α-tocopherol acetate (α-TAc), as the stable vitamin C and vitamin E derivative, respectively, are often applied to skin care products for reducing UV damage. The encapsulation of MAAP (0.5%, g/mL) and α-TAc (5%, g/mL) together within the polyacrylonitrile (PAN) nanofibers was demonstrated using a coaxial electrospinning technique. The structure and morphology characterizations of the core-shell fibers MAAP/α-TAc-PAN were investigated by SEM, FTIR and XRD. As a negative control, the blend nanofibers MAAP/α-TAc/PAN were prepared from a normal electrospinning method. The results from SEM indicated that the morphology and diameter of the nanofibers were influenced by concentration of spinning solution, the polymer component of the shell, the carrying agent of the core and the fabricating methods, and the core-shell nanofibers obtained at the concentration of 8% had finer and uniform structure with the average diameters of 200 ± 15 nm. From in vitro release studies it could be seen that both different fiber specimens showed a gradual increase in the amount of α-TAc or MAAP released from the nanofibers. Furthermore, α-TAc and MAAP released from the blend nanofibers showed the burst release at the maximum release of ∼15% and ∼40% during the first 6 h, respectively, but their release amount from the core-shell nanofibers was only 10–12% during the initial part of the process. These results showed that core-shell nanofibers alleviated the initial burst release and gave better sustainability compared to that of the blend nanofibers. The present study would provide a basis for further optimization of processing conditions to obtain desired structured core-shell nanofibers and release kinetics for practical applications in dermal tissue.
Co-reporter:Jing Quan, Yang Yu, Christopher Branford-White, Gareth R. Williams, Deng-Guang Yu, Wei Nie, Li-Min Zhu
Colloids and Surfaces B: Biointerfaces 2011 Volume 88(Issue 1) pp:304-309
Publication Date(Web):1 November 2011
DOI:10.1016/j.colsurfb.2011.07.006
Fast-dissolving drug delivery membranes for poorly water-soluble drugs were prepared by electrospinning using feruloyl-oleyl-glycerol (FOG) as a model drug and polyvinylpyrrolidone (PVP) K90 as a polymer matrix in a mixed solvent of chloroform/ethanol (4:1, v/v). Results from Fourier-transform infrared spectroscopy (FT-IR) illustrated good compatibility between FOG and PVP as well as a good distribution of FOG within the fibers. The morphology and diameter of the fibers were influenced by the concentration of PVP and the applied voltage. When the PVP concentration was 5% (w/v) and the applied voltage was 14 kV, uniform and smooth fibers were obtained, with diameter 700–800 nm. Wetting time assays confirmed fast-dissolving properties with the average dissolution time for FOG-loaded PVP fiber membranes being 2.0 ± 1.5 s. These results demonstrate the potential of electrospinning solid dispersions to improve the dissolution profile of poorly water-soluble drugs.Graphical abstractHighlights► Fast-dissolving drug delivery membranes of the poorly water-soluble drug FOG and PVP K90 were prepared by electrospinning. ► Uniform and smooth fibers with diameter 700–800 nm were obtained using the 5% (w/v) PVP concentration and 14 kV. ► Wetting time assays of FOG-loaded PVP fiber membranes were 2.0 ± 1.5 s.
Co-reporter:Ming-Min Song, Christopher Branford-White, Hua-Li Nie, Li-Min Zhu
Colloids and Surfaces B: Biointerfaces 2011 Volume 84(Issue 2) pp:477-483
Publication Date(Web):1 June 2011
DOI:10.1016/j.colsurfb.2011.02.002
Thermosensitive core–shell magnetic composite particles with a magnetic silica core and a rich poly (N-vinylcaprolactam) (PNVCL) shell layer were developed for studying the adsorption of bovine serum albumin (BSA) in a batch system. Various analytical and spectroscopic techniques including SEM, FT-IR, VSM and DSC were used to characterize the adsorbents prepared in this study. The combined effects of operating parameters such as initial temperature, pH and initial BSA concentration on the adsorption were analyzed using response surface methodology. The optimum conditions were 40 °C, pH 4.68, and initial BSA concentration 2.0 mg/mL. Desorption experiments were conducted by altering the system temperature where a high recovery rate of protein was obtained. The separation process developed here indicates that the dual-responsive smart adsorbent could be an ideal candidate for the separation of protein.Graphical abstractResearch highlights► A simple method for the fabrication of a smart material with a γ-Fe2O3/SiO2 core and thermosensitive poly (N-vinylcaprolactam) (PNVCL) shell was developed. ► The LCST of poly (N-vinylcaprolactam) was not significantly changed after encapsulating the γ-Fe2O3/SiO2 core. ► Response surface methodology (RSM) analysis showed that temperature and initial BSA concentration were the main factors that affected the adsorption capacity. ► The desorption process revealed that temperature played an important role in protein recovery.
Co-reporter:Chengyao Wu;Jing Quan;Jiangang Xie;Christopher Branford-White
Polymer Bulletin 2011 Volume 67( Issue 4) pp:593-608
Publication Date(Web):2011 August
DOI:10.1007/s00289-010-0409-4
A facile and efficient enzymatic and polymerization process was used to prepare polymeric prodrugs of ketoprofen with saccharide side chains. The chains included branches that included glucose, mannose, galactose, and lactose, and these were synthesized through free radical reaction. The prodrugs were characterized by FT-IR, NMR, and GPC and drug-loading capacity was influenced by varying the ratios of initiator and monomers (range 32.13 and 68.56% w/w). In vitro release characteristics of the polymeric drugs were systematically evaluated over the pH range 1.2–8.0 and the release profiles indicated that the hydrolytic nature of polymers were strongly depended on the variation in saccharide content, carbon chain length, and pH. The outcomes from this study demonstrate the importance of carbohydrate structures and how these are linked to drug release.
Co-reporter:Jie Han, Christopher J. Branford-White, Li-Min Zhu
Carbohydrate Polymers 2010 Volume 79(Issue 1) pp:214-218
Publication Date(Web):5 January 2010
DOI:10.1016/j.carbpol.2009.07.052
Poly(ε-caprolactone) (PCL)/poly(trimethylene carbonate) (PTMC) blend nanofibers have been prepared for the first time using an electrospinning process. The mixed dichloromethane (DCM) and N,N-dimethylformamide (DMF) (75/25, v/v) was found to be the most suitable solvent for electrospinning. Various blends of PCL/PTMC solutions were investigated for the formation of nano-scale fibers and it was found that the average diameter of the fibers was reduced and the morphology became finer when PTMC content was increased. FT-IR and DSC analysis indicated that the molecular interactions between PCL and PTMC were weak and they were phase-separated in the fibers. Due to the biocompatible properties of PCL and PTMC, the spun nanofibers developed here could have applications in the biomedical field.
Co-reporter:Yuan-Qing Ling, Hua-Li Nie, Sai-Nan Su, Christopher Branford-White, Li-Min Zhu
Separation and Purification Technology 2010 Volume 73(Issue 3) pp:343-348
Publication Date(Web):8 July 2010
DOI:10.1016/j.seppur.2010.04.020
This investigation attempts to study and optimize the affinity partitioning conditions of papain in an aqueous two-phase system (ATPS). Reactive Red 120 was added to the ATPS as a free affinity dye ligand and five factors (pH, PEG concentration, ammonium sulfate, sodium chloride and dye) that influence the papain partitioning were analyzed using response surface methodology. The optimum conditions were determined as PEG 0.102 g/ml, ammonium sulfate 0.17 g/ml, sodium chloride 25 mg/ml, Reactive Red 120 4.5 μg/ml and pH 8.0. It was observed that sodium chloride increased papain partitioning and Reactive Red 120 had little effect on partitioning. The optimal condition gave a KU value for papain partitioning of 1.92 with a yield of 50.6%.
Co-reporter:Deng-Guang Yu;Christopher Branford-White;Lan Li;Xiao-Mei Wu
Journal of Applied Polymer Science 2010 Volume 117( Issue 3) pp:1509-1515
Publication Date(Web):
DOI:10.1002/app.32019
Abstract
Drug delivery systems (DDS) derived from drug-loaded fibers have attracted increasing attention in recent years. In this study, drug-loaded nanofibers with varying drug-to-polymer ratios were prepared using electrospinning with acyclovir (ACY) as the model drug and polyacrylonitrile (PAN) as the filament-forming matrix polymer. The compatibility of ACY with PAN was investigated by FTIR, DSC, XRD, and morphological studies. The obtained results clearly demonstrated that ACY had good compatibility with PAN and was able to be evenly distributed in the polymer fiber matrix. ACY present in the drug-loaded fibers with a drug content of 10 wt % was in an amorphous state. As the ACY contents in the fibers increased up to 20 wt % drug crystals began to form and ACY separated from the fiber matrix. FTIR results illustrated that the main interactions between PAN and ACY was hydrogen bonding and data from 1H-NMR showed that ACY was able to retain its chemical integrity during the electrospinning. All the fibers with varying drug content provided sustained drug release profiles over a 12-h period. The drug-loaded fibers prepared in this study could provide new approaches for developing novel transdermal DDS or skin topical DDS. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Deng-Guang Yu, Christopher J. Branford-White, Nicholas P. Chatterton, Kenneth White, Li-Min Zhu, Xia-Xia Shen, and Wei Nie
Macromolecules 2010 Volume 43(Issue 24) pp:10743-10746
Publication Date(Web):November 29, 2010
DOI:10.1021/ma1024363
Co-reporter:Xiao-mei Wu;Christopher J. Branford-White
Journal of Materials Science: Materials in Medicine 2010 Volume 21( Issue 8) pp:2403-2411
Publication Date(Web):2010 August
DOI:10.1007/s10856-010-4100-y
Cellulose acetate (CA) fibers loaded with the ester prodrugs of naproxen, including methyl ester, ethyl ester and isopropyl ester, were prepared through electrospinning using acetone/N,N-dimethylacetamide(DMAc)/ethanol (4:1:1, v/v/v) as solvent. The chemical and morphological characterizations of the medicated fibers were investigated by means of SEM, DSC, XRD and FTIR, as well as the studies of the drug release properties. The results indicated that the morphology and diameter of the fibers were influenced by the concentration of spinning solution, applied voltage, electrospun solvent and the surfactants. The average diameters of the fibers ranged between 100 and 500 nm for three prodrugs. There was good compatibility between CA and three prodrugs in the blended fibers, respectively. In vitro release indicated that constant drug release from the fiber was observed over 6 days. The prodrugs were successfully encapsulated into the fibers, and this system was stable in terms of effectiveness in release.
Co-reporter:Shu-Bai Li;Hua-Li Nie;Hai-Tao Zhang;Yong Xue
Applied Biochemistry and Biotechnology 2010 Volume 162( Issue 3) pp:641-653
Publication Date(Web):2010 October
DOI:10.1007/s12010-009-8760-3
This study demonstrates that aminoethylisothiourea (AET), a potent inhibitor of inducible nitric oxide synthase, is an irreversible competitive inhibitor of mushroom tyrosinase by chelation to the active site of tyrosinase when l-3,4-dihydroxyphenylalanine was assayed spectrophotometrically. The spectrophotometric recordings of the inhibition of tyrosinase by AET were characterized by the presence of a lag period prior to the attainment of an inhibited steady-state rate. The lag period corresponded to the time in which AET was reacting with the enzymatically generated o-quinone. Increasing AET concentrations provoked longer lag periods as well as a concomitant decrease in the tyrosinase activity. Both lag period and steady-state rate were dependent on AET, substrate, and tyrosinase concentrations. The inhibition of diphenolase activity of tyrosinase by AET showed positive kinetic cooperativity which arose from the protection of both substrate and o-quinone against inhibition by AET. The UV-visible spectrum of a mixture of tyrosinase and AET exhibited a characteristic shoulder peak ascribed to the chelation of AET to the active site of tyrosinase. Moreover, the presence of copper ions only partially prevented but not reverted mushroom tyrosinase inhibition when CuSO4 was added to the assay medium on tyrosinase activity.
Co-reporter:Haitao Zhang;Chengyao Wu;Yunlong Zhang
Journal of Materials Science 2010 Volume 45( Issue 9) pp:2296-2304
Publication Date(Web):2010 May
DOI:10.1007/s10853-009-4191-3
Electrospun hybrid chitosan/nylon-6 nanofibrous mats with fiber diameters in the range of 80–310 nm were successfully fabricated using an electrospinning method. Nanofibrous membranes were prepared by nucleophilic reaction of the chitosan’s hydroxyl and amidocyanogen with the triazinyl chloride of Cibacron Blue F3GA (CB) ligand. This system was used to study the purification of papain. Physical and chemical properties of the affinity membrane were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), contact angle (CA) and element analysis (EA). The equilibrium adsorption capacity (from Langmuir isotherm data) for papain was 93.46 mg/g affinity membrane. Fifteen layers of the composite affinity membrane were packed into a spin column to separate papain from raw material. Significant amount of the adsorbed papain (about 90.4%) was eluted by 1.0 M NaSCN at pH 9.0, and 4.8-fold purification was achieved in a single step. Experiments on regeneration and dynamic adsorption were also performed. It is shown that this system has the potential to be developed for the industrial purification of the papain.
Co-reporter:Yan Zheng;Christopher Branford-White
Journal of the American Oil Chemists' Society 2010 Volume 87( Issue 3) pp:305-311
Publication Date(Web):2010 March
DOI:10.1007/s11746-009-1496-y
Concerns about the use of chemical synthetic antioxidants that promote carcinogenesis has led to the development of natural antioxidants. Ferulic acid (4-hydroxy-3-methoxy cinnamic acid, FA) is a monophenolic phenylpropanoid present in the plant kingdom. It has shown a high antioxidant capacity and biological activities, including antiviral, anticarcinogenic and antimicrobial ones. However, due to poor solubility in hydrophobic media, FA can only be used in aqueous environments and this is a key factor that to a certain extent limits its application and bioavailability. In the present study, novel feruloylated lipids 1(3)-feruloyl-monobutyryl-glycerol (FMB) and 1(3)-feruloyl-dibutyryl-glycerol (FDB) were prepared by lipase-catalysed transesterification between FA and tributyrin. The structure of FMB and FDB was confirmed by NMR and ESI-MS, respectively. The radical scavenging and antioxidant properties of FA, FMB and FDB were evaluated using several different antioxidant assays, including hydroxyl radical scavenging, superoxide anion radical scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH·) radical scavenging, inhibition of peroxidation of linoleic acid and reducing power. The antioxidant activities decreased in the following order: BHT ≥ FMB > FDB > FA. The results suggested that FMB and FDB exhibited a strong effect against oxidation in lipophilic systems making them promising antioxidants.
Co-reporter:Yang Yu;Yan Zheng;Jing Quan;Cheng-Yao Wu
Journal of the American Oil Chemists' Society 2010 Volume 87( Issue 12) pp:1443-1449
Publication Date(Web):2010 December
DOI:10.1007/s11746-010-1636-4
A facile and efficient enzymatic synthesis approach to synthesize feruloylated lipids, which are composed of 1(3)-feruloyl-monooleyl-glycerol and 1(3)-feruloyl-dioleyl-glycerol, through lipase-catalyzed transesterification using vinyl ferulate (VF) and ethyl ferulate (EF) as substrate, respectively, with triolein was developed. When VF was used as substrate, a maximum of conversion yield of 91.1% was obtained at 55 °C, 20 mg/mL enzyme content, water activity (aw) = 0.07, 62 h. This was greater than that when EF was used as substrate (69.6%, 50 °C, 33.3 mg/mL enzyme content, aw = 0.07, 96 h). Candida antarctica lipase (Novozym 435) can be reused for 13 runs without evident loss in activity and stability when VF was used as substrate. The results demonstrate that VF has greater synthetic efficiency and it provides another effective approach to prepare feruloylated lipids under normal pressure, making industry application feasible.
Co-reporter:Haitao Zhang, Shubai Li, Christopher J. Branford White, Xin Ning, Huali Nie, Limin Zhu
Electrochimica Acta 2009 Volume 54(Issue 24) pp:5739-5745
Publication Date(Web):1 October 2009
DOI:10.1016/j.electacta.2009.05.021
Composite membranes of nylon-6/chitosan nanofibers with different weight ratio of nylon-6 to chitosan were fabricated successfully using electrospinning. Morphologies of the nanofibers were investigated by scanning electron microscopy (SEM) and the intermolecular interactions of the nylon-6/chitosan complex were evaluated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) as well as mechanical testing. We found that morphology and diameter of the nanofibers were influenced by the concentration of the solution and weight ratio of the blending component materials. Furthermore FT-IR analyses on interactions between components demonstrated an IR band frequency shift that appeared to be dependent on the amount of chitosan in the complex. Observations from XRD and DSC suggested that a new fraction of γ phase crystals appeared and increased with the increasing content of chitosan in blends, this indicated that intermolecular interactions occurred between nylon-6 and chitosan. Results from performance data in mechanical showed that intermolecular interactions varied with varying chitosan content in the fibers. It was concluded that a new composite product was created and the stability of this system was attributed to strong new interactions such as hydrogen bond formation between the nylon-6 polymers and chitosan structures.
Co-reporter:Yu-Ting Zhou, Hua-Li Nie, Christopher Branford-White, Zhi-Yan He, Li-Min Zhu
Journal of Colloid and Interface Science 2009 Volume 330(Issue 1) pp:29-37
Publication Date(Web):1 February 2009
DOI:10.1016/j.jcis.2008.10.026
Chitosan-coated magnetic nanoparticles (CCMNPs), modified with a biodegradable and eco-friendly biologic reagent, α-ketoglutaric acid (α-KA), was used as a magnetic nanoadsorbent to remove toxic Cu2+ ions from aqueous solution. The prepared magnetic nanoadsorbents were characterized by FTIR, TEM, VSM, XRD, and EDS. Factors influencing the adsorption of Cu2+, e.g., initial metal concentration, initial pH, contact time and adsorbent concentration were investigated. TEM images show that the dimension of multidispersed circular particles is about 30 nm and no marked aggregation occurs. VSM patterns indicate superparamagnetic properties of magnetic nanoadsorbents. EDS pictures confirm the presence of the Cu2+ on the surface of magnetic nanoadsorbents. Equilibrium studies show that Cu2+ adsorption data follow Langmuir model. The maximum adsorption capacity (qmaxqmax) for Cu2+ ions was estimated to be 96.15 mg/g, which was higher than that of pure CCMNPs. The desorption data show no significant desorption hysteresis occurred. In addition, the high stability and recovery capacity of the chitosan-coated magnetic nanoparticles modified with α-ketoglutaric acid (α-KA-CCMNPs) suggest that these novel magnetic nanoadsorbents have potential applications for removing Cu2+ from wastewater.Chitosan-coated magnetic nanoparticles modified with α-ketoglutaric acid were successfully prepared as a potent and specific magnetic nanoadsorbent for removing Cu2+ from aqueous solution.
Co-reporter:Haitao Zhang, Huali Nie, Shubai Li, Christopher J. Branford White, Limin Zhu
Materials Letters 2009 Volume 63(13–14) pp:1199-1202
Publication Date(Web):31 May 2009
DOI:10.1016/j.matlet.2009.02.035
The electrospinning of polyacrylonitrile (PAN)/hydroxyethyl cellulose (HEC) was performed with glutaraldehyde as a cross linker to fabricate highly hydrophile nanofibers. The concentration of the spinning solution and the ratio of HEC/PAN were varied and adjusted to get smooth nanofibers. The nanofibers were characterized by SEM, FT-IR and contact angle. SEM images showed that the scope of the diameters was 100–300 nm. The nanofibers became thick with the ratio of the HEC/PAN increasing. FT-IR indicated that there could be interactions between HEC and PAN. Contact angle measurement revealed that the increased ratio of HEC and the crosslinking led improvement in the hydrophilicity of PAN/HEC composite nanofibers.
Co-reporter:Deng-Guang Yu;Xiao-Fei Zhang;Xia-Xia Shen;Chris Brford-White
Polymer International 2009 Volume 58( Issue 9) pp:1010-1013
Publication Date(Web):
DOI:10.1002/pi.2629
Abstract
BACKGROUND: Drug-loaded electrospun ultrafine fibers have the advantages of both nanoscale drug delivery systems and conventional solid dosage forms. To improve the control of drug release, the combined use of electrospinning and pharmaceutical polymers has attracted increasing interest recently.
RESULTS: Ultrafine drug-loaded polyvinylpyrrolidone fibers were successfully prepared using an electrospinning process with ibuprofen as the active pharmaceutical ingredient and polyvinylpyrrolidone K30 as the filament-forming polymer. The analytical results from scanning electron microscopy, differential scanning calorimetry and Fourier transform infrared spectroscopy indicated that the drug had good compatibility with the polymer and that the drug was well distributed in the ultrafine fibers as an amorphous physical form. In vitro dissolution tests showed that the fiber mats were able to dissolve within 10 s through a polymer-controlled mechanism.
CONCLUSION: The fast dissolution of drug-loaded fibers may lead to applications that improve dissolution rates of poorly water-soluble drugs, or that involve the preparation of oral fast-dissolving drug delivery systems. Copyright © 2009 Society of Chemical Industry
Co-reporter:Yan Zheng;Jing Quan;Xin Ning
World Journal of Microbiology and Biotechnology 2009 Volume 25( Issue 1) pp:
Publication Date(Web):2009 January
DOI:10.1007/s11274-008-9858-4
Lipase-catalyzed transesterification of soybean oil and methanol for biodiesel production in tert-amyl alcohol was investigated. The effects of different organic medium, molar ratio of substrate, reaction temperature, agitation speed, lipase dosage and water content on the total conversion were systematically analyzed. Under the optimal conditions identified (6 mL tert-amyl alcohol, three molar ratio of methanol to oil, 2% Novozym 435 lipase based on the soybean oil weight, temperature 40°C, 2% water content based on soybean oil weight, 150 rpm and 15 h), the highest biodiesel conversion yield of 97% was obtained. With tert-amyl alcohol as the reaction medium, the negative effects caused by excessive molar ratio of methanol to oil and the by-product glycerol could be reduced. Furthermore, there was no evident loss in the lipase activity even after being repeatedly used for more than 150 runs.
Co-reporter:Shu-Bai Li;Yong Xue;Xin-Yu Lv;Hua-Li Nie
The Protein Journal 2009 Volume 28( Issue 3-4) pp:182-188
Publication Date(Web):2009 May
DOI:10.1007/s10930-009-9182-3
This investigation, in vitro, shows that ozagrel, an antithrombotic drug, inhibited both monophenolase and diphenolase activities of mushroom tyrosinase when l-tyrosine and l-DOPA were assayed spectrophotometrically, respectively. The IC50 values, for monophenolase and diphenolase activities, were 1.35 and 3.45 mM, respectively. Ozagrel was estimated to be a reversible mixed-type inhibitor of diphenolase activity with the constants (KS1, KS2, Ki1, and Ki2) determined to be 2.21, 3.89, 0.454, and 0.799 mM, repectively. Increasing ozagrel concentrations provoked longer lag periods as well as a concomitant decrease in the monophenolase activity. Inhibition experiment demonstrated that ozagrel bound the enzyme at a site distincted from the substrate active site, but it bound to either E (Enzyme) or ES (Enzyme-Substrate) complex.
Co-reporter:Tian-Xiang Chen, Hua-Li Nie, Shu-Bai Li, Christopher Branford-White, Sai-Nan Su, Li-Min Zhu
Colloids and Surfaces B: Biointerfaces 2009 Volume 72(Issue 1) pp:25-31
Publication Date(Web):1 August 2009
DOI:10.1016/j.colsurfb.2009.03.012
Novel membranes that involve the immobilization of Reactive Red 120 or Reactive Brown 10 as dye ligands were prepared. These were used in the purification of papain from papaya powder extracts. Papain adsorption capacities for the Red 120 and Brown 10 membranes were 143.6 mg/g and 107.3 mg/g, respectively. The effectiveness of adsorption was demonstrated by Freundlich isotherm proficiency. The enzyme was eluted from the respective dye membranes using 1.0 M NaCl at pH 6.0 and yields of over 80% were found for the Red 120–CS (chitosan)–nylon membrane whereas only a 50% recovery was possible using the Brown 10–CS–nylon membranes. It is concluded that Red 120–CS–nylon membranes could play an active role in the separation and purification of papain from crude extracts. This system has the potential to be developed for the commercial isolation of the protein.
Co-reporter:Zong-Hui Ma, Deng-Guang Yu, Christopher J. Branford-White, Hua-Li Nie, Zai-Xia Fan, Li-Min Zhu
Colloids and Surfaces B: Biointerfaces 2009 Volume 69(Issue 1) pp:85-90
Publication Date(Web):15 February 2009
DOI:10.1016/j.colsurfb.2008.11.005
Tamoxifen microcapsules and drug loaded medicated fabrics were investigated. The microcapsules were prepared using a complex coacervation procedure involving gelatin B and acacia gum. The morphology, particle size, drug loading capacity and in vitro release characteristics of the drug microcapsules were optimized for coating tamoxifen microcapsules onto the cotton fabrics. Infrared (IR) spectra and SEM were used to characterize the medicated fabrics and air permeability and laundering testing were undertaken to determine the efficiency and effectiveness of the system. Results showed that optimum condition for the microcapsules was at drug/polymer ratio 1:4, polymer concentration 3%, and rate of stirring 1000 rpm. In vitro release assays demonstrated that the tamoxifen was liberated over 10 h after an initial bust rate period. SEM images illustrated that the tamoxifen microcapsules were spherical in shape and were also tightly fixed on to the cotton fabrics fast. These observations demonstrate that we have designed and fabricated a medicated system that potentially could be applied within a transdermal drug delivery system and so act in a system for the treatment of breast cancer.
Co-reporter:Yu-Ting Zhou, Christopher Branford-White, Hua-Li Nie, Li-Min Zhu
Colloids and Surfaces B: Biointerfaces 2009 Volume 74(Issue 1) pp:244-252
Publication Date(Web):1 November 2009
DOI:10.1016/j.colsurfb.2009.07.026
In order to better understand the adsorption mechanism of chitosan-coated magnetic nanoparticles modified with α-ketoglutaric acid (α-KA-CCMNPs), the removal of Cu2+ by α-KA-CCMNPs from aqueous solution was investigated in a batch system at 18, 35 and 50 °C. Different experimental approaches were applied to show mechanistic aspects, such as adsorption isotherms, kinetics and thermodynamics studies. Adsorption equilibrium studies showed that Cu2+ adsorption followed Langmuir model. The kinetics of the interactions was best described by pseudo-second-order mechanism. The thermodynamic parameters (ΔG°, ΔH° and ΔS°) analysis predicted that the adsorption process was strongly dependent on temperature of medium, and spontaneous and endothermic process. The XPS combined with FT-IR spectra revealed that N atom of –NH– group and O atom of carboxyl group in α-KA-CCMNPs coordinated with Cu2+. Experimental results from this study provide data that would be required if this heavy metal adsorption system was to be “scaled up” for industrial application.
Co-reporter:Chun-Xiang Chen;Bo Jiang;C. Branford-White
Biochemistry (Moscow) 2009 Volume 74( Issue 1) pp:36-40
Publication Date(Web):2009/01/01
DOI:10.1134/S0006297909010052
Alkylation of a cysteine residue in papain with a pyridoxamine (PX) cofactor was carried out. The resulting semisynthetic enzyme (papain-PX) has no detectable protease activity but has the ability to catalyze enantioselective reductive amination of α-keto acids. The conjugate was characterized by ion-exchange chromatography, and the optimal reaction conditions were found. We report that papain-PX reductively aminates the alkyl side chain of functionalized α-keto acids to give the respective α-amino acids with high enantioselectivities, greater than 70%. Based on these studies, we propose a new model for the catalytic activity of the semisynthetic enzyme with Interchem software. The results of the study demonstrate the effectiveness of the modified enzyme and its potential for engineering new catalytic specificity.
Co-reporter:Jing Quan;Yan-Qian Chai
World Journal of Microbiology and Biotechnology 2009 Volume 25( Issue 3) pp:475-480
Publication Date(Web):2009 March
DOI:10.1007/s11274-008-9912-2
A facile and fast approach for the purification of deoxycytidine kinase (dCK) from calf thymus was developed using a fast performance liquid chromatography system. A 73-fold enrichment of the enzyme was noted compared to unfractionated dCK. Characterization studies demonstrated that dCK had a molecular mass of 31 kDa using SDS–PAGE, an optimum pH of 7.0 and the enzyme maintained stability between 30 and 40°C. The rapid preparation of dCK demonstrated here will be valuable in the synthesis of nucleotide analogs.
Co-reporter:Yan Zheng, Jing Quan, Xin Ning and Li-Min Zhu
Journal of Agricultural and Food Chemistry 2008 Volume 56(Issue 23) pp:11493-11498
Publication Date(Web):November 11, 2008
DOI:10.1021/jf802478r
Response surface methodology was successfully employed to optimize lipase-catalyzed synthesis of feruloyl butyryl glycerides (FBGs). The effects of the reaction parameters, including the reaction time, reaction temperature, enzyme concentration, substrate molar ratio, and water activity, and the interaction parameters were examined. The analysis suggested that the conversion of the FBGs was significantly (p < 0.05) affected by independent factors of reaction time, reaction temperature, substrate molar ratio, and water activity as well as interactive terms of reaction temperature/reaction time, reaction temperature/enzyme concentration, substrate molar ratio/reaction temperature, water activity/reaction temperature, reaction time/enzyme concentration, and enzyme concentration/water activity. The highest conversion yield of FBGs was 81.2% at the following optimized reaction conditions: reaction temperature of 53.6 °C, reaction time of 5.5 days, enzyme concentration of 50.8 mg/mL, water activity of 0.14, and substrate molar ratio of 2.9. The conversion is higher as compared to that at the conditions before optimization.
Co-reporter:Deng Guang Yu;Christopher J. Branford-White;Xiang Liang Yang
Journal of Pharmaceutical Sciences 2008 Volume 97( Issue 9) pp:3666-3690
Publication Date(Web):
DOI:10.1002/jps.21284
Abstract
Three-dimensional printing (3DP) is a rapid prototyping (RP) technology. Prototyping involves constructing specific layers that uses powder processing and liquid binding materials. Reports in the literature have highlighted the many advantages of the 3DP system over other processes in enhancing pharmaceutical applications, these include new methods in design, development, manufacture, and commercialization of various types of solid dosage forms. For example, 3DP technology is flexible in that it can be used in applications linked to linear drug delivery systems (DDS), colon-targeted DDS, oral fast disintegrating DDS, floating DDS, time controlled, and pulse release DDS as well as dosage form with multiphase release properties and implantable DDS. In addition 3DP can also provide solutions for resolving difficulties relating to the delivery of poorly water-soluble drugs, peptides and proteins, preparation of DDS for high toxic and potent drugs and controlled-release of multidrugs in a single dosage forms. Due to its flexible and highly reproducible manufacturing process, 3DP has some advantages over conventional compressing and other RP technologies in fabricating solid DDS. This enables 3DP to be further developed for use in pharmaceutics applications. However, there are some problems that limit the further applications of the system, such as the selections of suitable excipients and the pharmacotechnical properties of 3DP products. Further developments are therefore needed to overcome these issues where 3DP systems can be successfully combined with conventional pharmaceutics. Here we present an overview and the potential 3DP in the development of new drug delivery systems. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:3666–3690, 2008
Co-reporter:Yan Zheng;Jing Quan;Bo Jiang
Journal of the American Oil Chemists' Society 2008 Volume 85( Issue 7) pp:635-639
Publication Date(Web):2008 July
DOI:10.1007/s11746-008-1248-4
The use of solvent engineering to achieve selective enzymatic synthesis of feruloylated acylglycerols during the transesterification of ethyl ferulate with TAG was investigated. Novozym 435 catalyzed transesterification of ethyl ferulate and TAG resulted in a mixture of feruloylated monoacylglycerols (FMAG) and feruloylated diacylglycerols (FDAG). These feruloylated acylglycerols have recently received much attention because of their health benefits, antioxidant properties and UV absorption. However, FMAG in a pure form is more advantageous than the FMAG–FDAG mixture in exhibiting stabilizing, emulsifying and conditioning properties. Thus, it is significant to perform efficient selectivity in the synthetic process. In this present study, the effect of various solvent mixtures, including unitary, binary and ternary organic media selective enzymatic synthesis of feruloylated acylglycerols was investigated by response surface methodology. Selectivity towards FMAG substantially increased from 14.5% in the unitary solvent n-hexane to 94.2% in the binary mixtures of 2-methyl-2-butanol (2M2B) and toluene (1:1, v/v). The maximum conversion achieved was 75.4% in this binary mixture medium. Analysis of variance (ANOVA) showed that 99.6% of the observed variation was explained by the polynomial model. Lack of fit analysis indicated that the regress equation was adequate for predicting the degree of the selectivity.
Co-reporter:Hua-Li Nie, Tian-Xiang Chen, Li-Min Zhu
Separation and Purification Technology 2007 Volume 57(Issue 1) pp:121-125
Publication Date(Web):1 October 2007
DOI:10.1016/j.seppur.2007.02.019
The adsorption of papain on the dye affinity membranes, the Cibacron Blue F3GA as a ligand, and the chitosan-coated nylon membrane as a base, under batch equilibrium experimental conditions at 277, 298, and 310 K was investigated. The experimental data were analyzed using two adsorption kinetic models: the pseudo-first-order and the pseudo-second-order. The pseudo-second-order kinetic model provided the better correlation to the experimental results. Studies showed that the adsorption of papain on dye affinity membranes could be described by the Freundlich isotherm. The thermodynamic constants of adsorption phenomena: ΔG°, ΔH°, and ΔS° were found as −12.58 kJ/mol (at 298 K), 17.81 kJ/mol, and 0.101 kJ/(mol K), respectively. The result shows that the adsorption of papain on the dye affinity membranes was endothermic and spontaneous.
Co-reporter:Yong Xue, Cheng-Yao Wu, Christopher J. Branford-White, Xin Ning, Hua-Li Nie, Li-Min Zhu
Journal of Molecular Catalysis B: Enzymatic (May 2010) Volume 63(Issues 3–4) pp:188-193
Publication Date(Web):1 May 2010
DOI:10.1016/j.molcatb.2010.01.018
Chemical modification of lysine residues in stem bromelain was carried out using two novel reagents pyromellitic anhydride acid and poly(maleic anhydride). About 60% and 57% of the residues in bromelain were found to be modified by pyromellitic anhydride and poly(maleic anhydride), respectively. The modification brought about enhancement of thermal stability and the resistance to alkali and the surfactant. The optimum pH shifted from 7 to 9. Thermodynamic parameters, ΔH*, ΔG* and ΔS*, were determined as a function of temperature. The kinetic constants Km of the modified enzymes were determined as 0.4092 × 10−2 and 0.2825 × 10−2 mol l−1, respectively. SDS-PAGE profiling revealed a major bands of native and modified enzyme with molecular weights of 26 and 28.5 kDa. The results of FT-IR studies suggested that the modification caused only local structural changes. These results provide guidance for future development of stable protein formulations.
Co-reporter:Juan Hu, He-Yu Li, Gareth R. Williams, Hui-Hui Yang, ... Li-Min Zhu
Journal of Pharmaceutical Sciences (March 2016) Volume 105(Issue 3) pp:1104-1112
Publication Date(Web):1 March 2016
DOI:10.1016/S0022-3549(15)00191-4
Fibers of poly(N-isopropylacrylamide) (PNIPAAm), ethyl cellulose (EC), and a blend of both were successfully fabricated by electrospinning. Analogous drug-loaded fibers were prepared loaded with ketoprofen (KET). Scanning and transmission electron microscopy showed that the fibers were largely smooth and cylindrical, with no phase separation observed. The addition of KET to the spinning solutions did not affect the morphology of resultant fibers, and no drug particles could be observed to separate from the polymer matrix. X-ray diffraction demonstrated that the drug was present in the amorphous physical form in the fiber matrix. There are significant intermolecular interactions between KET and polymers, as evidenced by IR spectroscopy and molecular modeling. Water contact angle measurements proved that the PNIPAAm and PNIPAAm/EC fibers switched from being hydrophilic to hydrophobic when the temperature was increased through the lower critical solution temperature of 32°C. In vitro drug release studies found that the PNIPAAm/EC blend nanofibers were able to synergistically combine the properties of the 2 polymers, giving temperature-sensitive systems with sustained release properties. In addition, they were established to be nontoxic and suitable for cell growth. This study demonstrates that electrospun-blend PNIPAAm/EC fibers comprise effective and biocompatible materials for drug delivery systems and tissue engineering.
Co-reporter:Yan Zheng, Xiao-Mei Wu, Christopher Branford-White, Xin Ning, Jing Quan, Li-Min Zhu
Journal of Molecular Catalysis B: Enzymatic (June 2009) Volume 58(Issues 1–4) pp:65-71
Publication Date(Web):1 June 2009
DOI:10.1016/j.molcatb.2008.11.005
A facile enzymatic synthesis approach to prepare novel feruloylated lipids through the lipase-catalyzed transesterification reaction of ethyl ferulate (EF) with tributyrin (TB) in toluene was investigated. The nuclear magnetic resonance (NMR) and electrospray ionization-mass spectroscopy (ESI-MS) analysis confirmed the formation of two major products, 1(3)-feruloyl-monobutyryl-glycerol (FMB) and 1(3)-feruloyl-dibutyryl-glycerol (FDB). The influences of different enzyme source, organic solvent, molar ratio, reaction temperature, agitation speed and water activity on the total conversion of reaction, distribution of FMB and FDB and selectivity of these two novel derivatives of FA were analyzed systematically. Under the optimal conditions, the highest conversion of feruloylated lipids achieved was 73.6%, which was composed of FMB 58.3% and FDB 13.1%, respectively. The enzyme can be reused for 14 runs without evident loss in activity and stability.
Co-reporter:Yan Li, Jing Quan, Christopher Branford-White, Gareth R. Williams, Jin-Xian Wu, Li-Min Zhu
Journal of Molecular Catalysis B: Enzymatic (April 2012) Volume 76() pp:15-22
Publication Date(Web):1 April 2012
DOI:10.1016/j.molcatb.2011.12.003
A biocatalyst was fabricated by the covalent immobilization of the enzyme catalase on a polyacrylonitrile (PAN) based nanofibrous membrane incorporating a glycopolymer. The glycopolymer poly-(6-O-vinylsebacoyl d-glucose) [poly-OVSEG] was synthesized by a water phase precipitation homopolymerization process, and its structure was characterized by Fourier transform infrared spectroscopy (FT-IR) and NMR. Composite membranes of PAN/poly-OVSEG nanofibers containing varying amounts (50–70%) of poly-OVSEG were subsequently prepared using electrospinning. The nanofibers were studied by scanning electron microscopy (SEM) and FT-IR. Their hydrophilicity was investigated by measuring water contact angles. With increasing content of poly-OVSEG, the contact angle decreases from 65.5 ± 2.5° to 15.2 ± 1.1°. Catalase was immobilized on the composite nanofibrous membranes by covalent binding. The maximum catalase adsorption capacity of the polyacrylonitrile-based nanofibrous membranes was observed to be ca. 46.5 mg/g. Over 50% of catalyst activity was retained and increased thermal stability observed post-immobilization (with maximum activity at pH 7.5 and 50 °C). This study demonstrates the potential of using electrospun membranes to improve the thermal and storage stabilities of biological catalysts.Download full-size image
Co-reporter:Jie Han, Tian-Xiang Chen, Christopher J. Branford-White, Li-Min Zhu
International Journal of Pharmaceutics (1 December 2009) Volume 382(Issues 1–2) pp:215-221
Publication Date(Web):1 December 2009
DOI:10.1016/j.ijpharm.2009.07.027
Novel electrospun poly(ɛ-caprolactone) (PCL)/poly(trimethylene carbonate) (PTMC) ultrafine composite fiber mats were prepared and used as drug-carrying materials to encapsulate the herbal medicine shikonin isolated from the plant Lithospermum erythrorhizon Sieb. et Zucc. The PCL/PTMC blended solutions in various ratios (9:1, 7:3, and 5:5, w/w) containing 1 and 5 wt.% shikonin were studied for electrospinning into nanoscale fiber mats. With good drug stability and high drug-loading efficacy, incorporation of shikonin in the polymer media did not appear to influence the morphology of the resulting fibers, as both the drug-free and the shikonin-loaded composite fibers remained unaltered, microscopically. The average diameter of the composite fibers decreased, and the morphology of the fibers became finer with the increasing content of PTMC. In vitro drug release studies demonstrated an initial rapid release of shikonin followed by a plateau after 11 h. It was found that the release behavior could be tailored by the PCL/PTMC blend ratio and drug-loading content. Moreover, the free radical scavenging activity and the antibacterial effects of the shikonin-loaded fiber mats indicated that it could act not only as a drug delivery system but also in the treatment of wound healing or dermal bacterial infections.
Co-reporter:Deng-Guang Yu, Li-Min Zhu, S. W. Annie Bligh, Christopher Branford-White and Kenneth N. White
Chemical Communications 2011 - vol. 47(Issue 4) pp:NaN1218-1218
Publication Date(Web):2010/11/24
DOI:10.1039/C0CC03521A
We show that coaxial electrospinning using organic solvent as the sheath fluid is a viable way to produce tailor-made nanofibers composed of polyvinylpyrrolidine, tristearic and naproxen. Self-assembled hybrid nanoparticles are generated from the composite nanofibers under aqueous conditions and particle size has a linear relationship with fiber diameter.
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