Co-reporter:Kun Wang, Meng-Qi He, Fu-Heng Zhai, Rong-Huan He, Yong-Liang Yu
Talanta 2017 Volume 166() pp:87-92
Publication Date(Web):1 May 2017
DOI:10.1016/j.talanta.2017.01.052
•A label-free and sandwich electrochemical biosensor was developed for MCF-7 detection.•Aptamer was anchored on the surface of gold electrode by using polyadenine instead of thiol.•The electrochemical biosensor offered high sensitivity and selectivity toward MCF-7 breast cancer cells.Simple, rapid, sensitive, and specific detection of cancer cells plays a pivotal role in the diagnosis and prognosis of cancer. A sandwich electrochemical biosensor was developed based on polyadenine (polydA)-aptamer modified gold electrode (GE) and polydA-aptamer functionalized gold nanoparticles/graphene oxide (AuNPs/GO) hybrid for the label-free and selective detection of breast cancer cells (MCF-7) via a differential pulse voltammetry (DPV) technique. Due to the intrinsic affinity between multiple consecutive adenines of polydA sequences and gold, polydA modified aptamer instead of thiol terminated aptamer was immobilized on the surface of GE and AuNPs/GO. The label-free MCF-7 cells could be recognized by polydA-aptamer and self-assembled onto the surface of GE. The polydA-aptamer functionalized AuNPs/GO hybrid could further bind to MCF-7 cells to form a sandwich sensing system. Characterization of the surface modified GE was carried out by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using Fe(CN)63-/4- as a redox probe. Under the optimized experimental conditions, a detection limit of 8 cells mL−1 (3σ/slope) was obtained for MCF-7 cells by the present electrochemical biosensor, along with a linear range of 10–105 cells mL−1. By virtue of excellent sensitivity, specificity and repeatability, the present electrochemical biosensor provides a potential application in point-of-care cancer diagnosis.
Co-reporter:Meng-Qi He;Kun Wang;Jin Wang;Yong-Liang Yu
Analytical and Bioanalytical Chemistry 2017 Volume 409( Issue 7) pp:1797-1803
Publication Date(Web):2017 March
DOI:10.1007/s00216-016-0123-7
To specifically and sensitively identify bisphenol A (BPA) with a simple and rapid method is very important for food safety. Using an anti-BPA aptamer and Mo2C nanotubes, we developed a label-free and low-background signal biosensor for BPA detection. The anti-BPA aptamer drastically increased the fluorescence signal of N-methylmesoporphyrin IX under an assistance of Help-DNA. Additionally, BPA can interact with the anti-BPA aptamer and switch its conformation to prevent the formation of a G-quadruplex, resulting in fluorescence quenching. Simultaneously, Mo2C nanotubes can reduce the background signals due to the adsorption of Help-DNA on their surface. This method shows a linear range of 2–20 nM with a detection limit of 2 nM for detecting BPA. This label-free BPA aptasensor with low background signal is inexpensive, easy to use, and can be applied to determine BPA in real water samples.
Co-reporter:Yang Zhang, Lu Han, Lin-Lin Hu, Yan-Qin Chang, Rong-Huan He, Ming-Li Chen, Yang Shu and Jian-Hua Wang
Journal of Materials Chemistry A 2016 vol. 4(Issue 30) pp:5178-5184
Publication Date(Web):11 Jul 2016
DOI:10.1039/C6TB00987E
A pH and redox responsive bi-trigger continuous drug release nanocarrier is developed by capping mesoporous carbon nanoparticles (MCNs) with polyacrylic acid (PAA), termed as PAA-ss-MCN. The nanocarrier contains disulfide bond units and exhibits pH responsive behavior. It provides promising potential for drug loading due to the internal uniform channels and large surface area of MCNs. PAA grafted on the exterior surface of MCNs acts as a gating layer, generating a novel nano-container and a pH-responsive intelligent nanovalve. By loading doxorubicin (DOX) in PAA-ss-MCN, its sequential release is achieved via two approaches: (1) the intracellular acidic environment induces partial release from the surface of the PAA gating layer, (2) release of the drug sealed in nanochannels via disruption of the integrity of the nanocarrier by glutathione (GSH) caused dissociation of disulfide bonds in the physiological environment. As a result, release of 62% loaded drug is readily achieved. After culturing with HeLa cells, DOX transports into the cell interior and therein exhibits pH- and GSH-sensitive release. As most tumor sites exhibit more acidic environments or high redox potential, the pH- and GSH-sensitive releasing capability of PAA-ss-MCN is particularly useful for controllable drug delivery by taking advantage of the inherent characteristics of tumor cells.
Co-reporter:Jingshuai Yang, Chao Liu, Yanan Hao, Xiangnan He, Ronghuan He
Electrochimica Acta 2016 Volume 207() pp:112-119
Publication Date(Web):20 July 2016
DOI:10.1016/j.electacta.2016.04.176
Imidazolium-type anion exchange membranes (AEMs) were prepared by functionalization of bromomethylated poly(2,6-dimethyl-1,4-phenyleneoxide) with six kinds of imidazole compounds, respectively, to investigate the correlation of the grafted imidazolium structure and the physicochemical properties of the membrane. The chemical structure of substituted groups in imidazolium cations would highly influence the ion exchange capacity, ionic conduction, mechanical strength, as well as stability in strong alkaline solutions of the AEMs. The membrane having C2-methyl and N3-butyl substituted groups in the imidazolium pendants exhibited superior properties among the prepared AEMs, i.e., an IEC of around 1.03 mmol g−1, hydroxide ion conductivity of 42.5 mS cm−1 at 80 °C, and tensile strength at break of 15.0 MPa, respectively. In addition, this membrane showed high alkaline stability and no obvious decline in conductivity was observed after being exposed to 1 M KOH at 60 °C for 180 h.
Co-reporter:Jingshuai Yang, Chao Liu, Liping Gao, Jin Wang, Yixin Xu, Tianyu Wang and Ronghuan He
RSC Advances 2016 vol. 6(Issue 66) pp:61029-61036
Publication Date(Web):20 Jun 2016
DOI:10.1039/C6RA10622F
Low cost poly(epichlorohydrin) (PECH) was modified with imidazolium groups to prepare high temperature proton exchange membranes. Chloromethyl groups in the structure of the PECH benefit its modification with no need for highly toxic and carcinogenic chloromethylation reagents. Both methylimidazole (MeIm) and triethoxysilylpropyldihydroimidazole (SiIm) were used to carry out the SN2 nucleophilic substitution for grafting the imidazolium groups onto the PECH. Meanwhile crosslinking of the modified PECH was achieved by forming a crosslinked silane network via the hydrolysis reaction of SiIm in an acid medium. Moreover, porous poly(tetrafluoroethylene) (PTFE) was used as the membrane matrix to enhance the mechanical strength of the fabricated membranes. The obtained PECH–SiIm–MeIm/PTFE membranes displayed phosphoric acid doping capacities of 110–170 wt% with low volume swelling ratios of less than 120%. Anhydrous proton conductivities of 0.010–0.063 S cm−1 were reached at elevated temperatures of 100–180 °C by the membranes with adequate mechanical strength. Fuel cell tests demonstrated the technical feasibility of acid doped PECH–SiIm–MeIm/PTFE membranes for high temperature proton exchange membrane fuel cells.
Co-reporter:Jingshuai Yang, Chao Liu, Liping Gao, Jin Wang, Yixin Xu and Ronghuan He
RSC Advances 2015 vol. 5(Issue 122) pp:101049-101054
Publication Date(Web):19 Nov 2015
DOI:10.1039/C5RA16554G
Simultaneously improving the proton conductivity and mechanical properties of a polymer electrolyte, especially to phosphoric acid doped membranes, is a challenge for the preparation of membrane materials in application in proton exchange membrane fuel cells. We prepared a novel composite membrane by introducing triazole functionalized graphene oxide into the polybenzimidazole for use as a high temperature proton exchange membrane. Increases in both proton conductivity and tensile strength were achieved by the composite membrane compared with the pure PBI membrane after doping with phosphoric acid. The triazole modified graphene oxide could disperse well in the polar organic solvent, which resulted in easy fabrication of the homogeneous membranes. The proposed material is a demonstration for designing and preparing inorganic composite polymer electrolytes with superior properties.
Co-reporter:Jingshuai Yang, Yixin Xu, Peipei Liu, Liping Gao, Quantong Che, Ronghuan He
Electrochimica Acta 2015 160() pp: 281-287
Publication Date(Web):
DOI:10.1016/j.electacta.2015.01.094
Co-reporter:Jilin Wang, Ronghuan He
Solid State Ionics 2015 Volume 278() pp:49-57
Publication Date(Web):1 October 2015
DOI:10.1016/j.ssi.2015.05.017
•Novel anion exchange membranes with interpenetrated network (IPN) structure•Increased tensile stress of the membrane with IPN structure•Decreased methanol permeability of the prepared membranes•High tolerance to alkaline solution of the membranesA high-strength anion exchange membrane with a full interpenetrating network (full-IPN) structure was prepared from quaternized chitosan (QCS), polyacrylamide (PAM) and polystyrene (PS). The influences of the component content of the membrane and crosslinking degree of the QCS on the mechanical properties, anionic conductivity as well as methanol permeability of the membranes were investigated. The results indicated that the full-IPN structure as well as the presence of the hydrophobic PS could improve the mechanical properties and decrease the methanol permeability of the membrane. Corresponding to the increase in the content of PAM/PS (the molar ratio of PAM/PS was 1:1) from 0 wt.% to 40 wt.% in the full-IPN membrane, the tensile stress was increased from 30.1 MPa to 43.9 MPa, the methanol permeability was decreased from 6.64 × 10− 6 cm2 s− 1 to 6.54 × 10− 7 cm2 s− 1, respectively. Anionic conductivities of 6.00 × 10− 3–1.26 × 10− 2 S cm− 1 were achieved at 80 °C for the obtained membranes. To the membranes with a QCS content of 60 wt.%, the conductivity and tensile stress of about 90% were maintained after soaking the membranes in 1 mol L− 1 KOH for 120 h, and a 10 mol L− 1 KOH for 50 h at room temperature, respectively.
Co-reporter:Jingshuai Yang, David Aili, Qingfeng Li, Yixin Xu, Peipei Liu, Quantong Che, Jens Oluf Jensen, Niels J. Bjerrum and Ronghuan He
Polymer Chemistry 2013 vol. 4(Issue 17) pp:4768-4775
Publication Date(Web):27 Jun 2013
DOI:10.1039/C3PY00408B
High molecular weight polybenzimidazole (PBI) was synthesized and grafted with benzimidazole pendant groups. The high molecular weight of PBI resulted in good film-forming properties and superior tensile strength. With a phosphoric acid doping level (ADL) of 13.1, a tensile strength of 16 MPa was achieved at room temperature. Grafting of benzimidazole moieties onto the PBI macromolecular chain introduced additional basic sites which allowed the membrane to achieve higher phosphoric acid uptakes. A molar acid conductivity, defined as the specific conductivity of each mole of doping acid, was proposed to evaluate the effective conductivity contributed from the doping acids. With a grafting degree of 5.3% and an ADL of 13.1, the PBI membranes exhibited a total conductivity of 0.15 S cm−1. A H2–air fuel cell based on this membrane showed a peak power density of 378 mW cm−2 at 180 °C without humidification.
Co-reporter:Gang Zhao, Shuai Chen, Jie Yue and Rong-huan He
Analytical Methods 2013 vol. 5(Issue 20) pp:5425-5430
Publication Date(Web):05 Aug 2013
DOI:10.1039/C3AY40845K
An imidazolium-containing sulfonated polyetheretherketone (SPEEK) composite, termed as SPEEK–Bmim, was prepared from SPEEK and 1-butyl-3-methylimidazolium hexafluorophosphate. This composite material was characterized by FT-IR, surface charge analysis and elemental analysis. The prepared material could selectively adsorb the protein hemoglobin (Hb). The adsorption efficiency was about 90%. The sorption capacity of the SPEEK–Bmim to Hb was 31.6 μg mg−1, and 84% of the retained Hb could be readily recovered by elution with 0.5% (m/v) aqueous sodium dodecyl sulfate (SDS) solution. The activity of the eluted Hb was about 91%. This ionic liquid-modified SPEEK composite was used practically for the isolation of Hb from human whole blood.
Co-reporter:Jingshuai Yang;Dr. David Aili;Dr. Qingfeng Li;Dr. Lars N. Cleemann;Dr. Jens Oluf Jensen; Niels J. Bjerrum; Ronghuan He
ChemSusChem 2013 Volume 6( Issue 2) pp:275-282
Publication Date(Web):
DOI:10.1002/cssc.201200716
Abstract
Covalently cross-linked polymer membranes were fabricated from poly(aryl sulfone benzimidazole) (SO2PBI) and poly(vinylbenzyl chloride) (PVBCl) as electrolytes for high-temperature proton-exchange-membrane fuel cells. The cross-linking imparted organo insolubility and chemical stability against radical attack to the otherwise flexible SO2PBI membranes. Steady phosphoric acid doping of the cross-linked membranes was achieved at elevated temperatures with little swelling. The acid-doped membranes exhibited increased mechanical strength compared to both pristine SO2PBI and poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole] (mPBI). The superior characteristics of the cross-linked SO2PBI membranes allowed higher acid doping levels and, therefore, higher proton conductivity. Fuel-cell tests with the cross-linked membranes demonstrated a high open circuit voltage and improved power performance and durability.
Co-reporter:Jingshuai Yang, Yixin Xu, Lu Zhou, Quantong Che, Ronghuan He, Qingfeng Li
Journal of Membrane Science 2013 446() pp: 318-325
Publication Date(Web):
DOI:10.1016/j.memsci.2013.07.004
Co-reporter:Jingshuai Yang, Qingfeng Li, Lars N. Cleemann, Chenxi Xu, Jens Oluf Jensen, Chao Pan, Niels J. Bjerrum and Ronghuan He
Journal of Materials Chemistry A 2012 vol. 22(Issue 22) pp:11185-11195
Publication Date(Web):02 Apr 2012
DOI:10.1039/C2JM30217A
Poly(aryl sulfone benzimidazole) (SO2PBI) and its copolymers with poly[2,2′-p-(phenylene)-5,5′-bibenzimidazole] (pPBI), termed as Co-SO2PBI, were synthesized with varied feeding ratios of 4,4′-sulfonyldibenzoic acid (SDBA) to terephthalic acid (TPA). Incorporation of the stiff para-phenylene and flexible aryl sulfone linkages in the macromolecular structures resulted in high molecular weight copolymers with good solubility. The chemical stability towards radical oxidation was improved for SO2PBI and its copolymer membranes due to the electron-withdrawing sulfone functional groups. Upon acid doping, the membrane swelling was reduced and the mechanical strength was improved, as compared with their meta structured analogues. At an acid doping level of 11 mol H3PO4 per average molar repeat unit, the Co-20%SO2PBI membrane exhibited a tensile strength of 16 MPa at room temperature and an H2-air fuel cell peak power density of 346 mW cm−2 at 180 °C at ambient pressure. Durability tests with the membrane under a constant current density of 300 mA cm−2 at 160 °C showed a degradation rate of 6.4 μV h−1 during a period of 2400 h, which was significantly lower than that for meta PBI membranes with a similar acid doping level.
Co-reporter:Jingshuai Yang, Qingfeng Li, Jens Oluf Jensen, Chao Pan, Lars N. Cleemann, Niels J. Bjerrum, Ronghuan He
Journal of Power Sources 2012 Volume 205() pp:114-121
Publication Date(Web):1 May 2012
DOI:10.1016/j.jpowsour.2012.01.038
A novel acid–base polymer membrane is prepared by doping of imidazolium polysulfone with phosphoric acid for high temperature proton exchange membrane fuel cells. Polysulfone is first chloromethylated, followed by functionalization of the chloromethylated polysulfone with alkyl imidazoles i.e. methyl (MePSU), ethyl (EtPSU) and butyl (BuPSU) imidazoliums, as revealed by 1H NMR spectra. The imidazolium polysulfone membranes are then doped with phosphoric acid and used as a proton exchange membrane electrolyte in fuel cells. An acid doping level of about 10–11 mol H3PO4 per mole of the imidazolium group is achieved in 85 wt% H3PO4 at room temperature. The membranes exhibit a proton conductivity of 0.015–0.022 S cm−1 at 130–150 °C under 15 mol% water vapor in air, and a tensile strength of 5–6 MPa at 130 °C under ambient humidity. Fuel cell tests show an open circuit voltage as high as 0.96 V and a peak power density of 175–204 mW cm−2 at 150 °C with unhumidified hydrogen and air under ambient pressure.Highlights► Synthetic modification of polysulfone with alkyl imidazoles to provide functional basic sites. ► Acid doping of the polymer membranes using phosphoric acid for obtaining proton conductivity. ► High acid doping levels and hence proton conductivity achieved. ► Membrane characterizations of the proton exchange membranes including swelling, conductivity, mechanical strength. ► Technical feasibility of the proton exchange membrane demonstrated by fuel cell tests.
Co-reporter:Yong-Liang Yu, Ying Jiang, Rong-Huan He
Talanta 2012 Volume 88() pp:352-357
Publication Date(Web):15 January 2012
DOI:10.1016/j.talanta.2011.10.052
A miniature analytical system based on a lab-on-valve platform is developed for trace metal analysis by bead injection spectroscopy. A multipurpose flow cell integrated into a lab-on-valve is furnished with two pieces of fiber optics to communicate with light source and charge coupled device (CCD) spectrometer, respectively, in order to monitor real-time absorbance of the samples. Micro-beads loaded with chromogenic reagent are packed into the multipurpose flow cell to form a renewable microcolumn for solid phase extraction by bead injection. When the sample solution flows through the microcolumn, the target analyte will be captured on the surface of beads and detected directly by the CCD spectrometer without elution. The beads are automatically discarded from the multipurpose flow cell after each analytical cycle. This analytical system was employed to determine trace copper by loading of a chromogenic reagent 2-carboxy-2′-hydroxy-5′-sulfoformazylbenzene (zincon) on the beads of an anion exchanger (Sephadex QAE A-25). With a sample volume of 2.5 mL, a detection limit of 3 μg L−1 and a linear range of 10–100 μg L−1 were obtained for copper, along with a RSD value of 2.5% (at the 50 μg L−1 level). The accuracy and practical applicability of the proposed system were validated by analysing certified reference materials, i.e., GBW10010, GBW09101, GBW08608, and further demonstrated by spiking recovery of copper in a water sample.Highlights► A more flexible and simple miniaturized analytical system for trace metal analysis. ► Selectively capture and detect target analyte by BIS without elution. ► Solid phase separation and spectrophotometric detection on a LOV platform. ► Trace copper analysis was made with high sensitivity, selectivity and applicability.
Co-reporter:Jingshuai Yang, Quantong Che, Lu Zhou, Ronghuan He, Robert F. Savinell
Electrochimica Acta 2011 Volume 56(Issue 17) pp:5940-5946
Publication Date(Web):1 July 2011
DOI:10.1016/j.electacta.2011.04.112
High temperature proton exchange membranes based on Nafion were prepared by incorporating the polymer with ionic liquid cation 1-butyl-3-methylimidazolium (BMIm) and doping with phosphoric acid (PA). We found that using the hydroxide form rather than the chloride form of BMIm incorporated more readily the BMIm cation into Nafion film. A mole ratio of about 2 of BMIm cation to Nafion repeat unit, i.e., λBMIm/Nafion, was reached with the hydroxide form BMIm. The incorporated BMIm cation enhanced the doping of phosphoric acid into Nafion. A proton conductivity of 10.9 mS cm−1 and a tensile stress at break of 5.3 MPa were achieved, respectively, with a composite membrane of Nafion/2.3BMIm/5.2PA in molar ratio at 160 °C without humidification.Highlights► High temperature proton exchange membranes of Nafion/BMIm/PA. ► BMImOH results in easy incorporation of ionic liquid cations in Nafion membranes. ► Low methanol permeability of Nafion/BMIm membranes. ► The incorporated ionic cation BMIm enhances the PA doping in Nafion.
Co-reporter:Jilin Wang, Ronghuan He, Quantong Che
Journal of Colloid and Interface Science 2011 Volume 361(Issue 1) pp:219-225
Publication Date(Web):1 September 2011
DOI:10.1016/j.jcis.2011.05.039
Anion exchange membranes with semi-interpenetrating polymer network (semi-IPN) were prepared based on quaternized chitosan (QCS) and polystyrene (PS). The PS was synthesized by polymerization of styrene monomers in the emulsion of the QCS in an acetic acid aqueous solution under nitrogen atmosphere at elevated temperatures. The semi-IPN system was formed by post-cross-linking of the QCS. A hydroxyl ionic conductivity of 2.80 × 10−2 S cm−1 at 80 °C and a tensile stress at break of 20.0 MPa at room temperature were reached, respectively, by the semi-IPN membrane containing 21 wt.% of the PS. The durability of the semi-IPN membrane in alkaline solutions was tested by monitoring the variation of the conductivity and the mechanical strength. The degradation of the conductivity at 80 °C was about 5% by immersing the membrane in a 1 mol L−1 KOH solution at room temperature for 72 h and at 60 °C for 50 h, respectively. The tensile stress at break at room temperature could maintain about 20.0 MPa for the membrane soaking in a 10 mol L−1 KOH solution at ambient temperature for more than 70 h. The water swelling of the semi-IPN membranes was discussed based on the stress relaxation model of polymer chains, and it obeyed the Schott’s second-order swelling kinetics.Graphical abstractThe semi-interpenetrating polymer network provides the membranes, based on the cross-linked quaternized chitosan and polystyrene, a higher tolerance to alkaline solutions.Highlights► Preparation of anion exchange membranes with semi-interpenetrating polymer network. ► The semi-IPN membranes of QCS and PS entail high tolerance to alkaline medium. ► Less swelling of the semi-IPN membrane due to the presence of hydrophobic PS. ► Improved stress of the semi-IPN membrane as a result of the semi-IPN.
Co-reporter:Quantong Che, Ronghuan He, Jingshuai Yang, Li Feng, Robert F. Savinell
Electrochemistry Communications 2010 Volume 12(Issue 5) pp:647-649
Publication Date(Web):May 2010
DOI:10.1016/j.elecom.2010.02.021
A composite membrane was fabricated using a novel approach based on the ionic liquids 1-butyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium hexafluorophosphate, sulfonated polyetheretherketone (SPEEK), and phosphoric acid. This proton conducting composite membrane shows promise for operation in high temperature proton exchange membrane fuel cells at working temperatures up to 160 °C without humidification. Proton conductivity at a level of 2.0 × 10− 2 S/cm was achieved at 160 °C by the composite membrane with a molar ratio of 1:0.6:9 for SPEEK, 1-butyl-3-methylimidazolium (BMIM) cation and phosphoric acid, respectively. The sulfonation degree was 0.643 per polymer repeat unit with over 90% of the sulfate fixed anions forming a salt complex with BMIM cations. The tensile stress at break of the composite membrane was 15.5 MPa at room temperature, and it decreased from 4.1 to 1.9 MPa when the temperature increased from 110 to 160 °C, respectively.
Co-reporter:Jingshuai Yang
Polymers for Advanced Technologies 2010 Volume 21( Issue 12) pp:874-880
Publication Date(Web):
DOI:10.1002/pat.1513
Abstract
Phosphoric acid doped poly (2, 2′-(m-phenylene)-5, 5′-bibenzimidazole) (PBI) membranes were prepared by dissolving PBI powders in 85% phosphoric acid at 190–200°C and then promoting gelation of the PBI by cooling the solutions to −18°C. The extent of acid doping of the PBI membranes was controlled by immersing the membrane in aqueous phosphoric acid solutions of different concentrations (acid de-doping). The process of the acid de-doping was faster than acid doping of membrane cast from N,N-dimethylacetamide (DMAc). The de-doping process caused shrinkage of the PBI membrane and thus an increase in the membrane strength due to the packing of PBI chains according to the X-ray diffraction analysis. The tensile stress and proton conductivity of the obtained PBI membranes with different acid doping levels were measured. For a PBI (ηIV: 0.58 dL · g−1) membrane with an acid doping level of 7.0 (molar number of doped acid per mole repeat unit of PBI), the stress at break and proton conductivity at 120°C without humidification were 2.6 MPa and 5.1 × 10−2 S · cm−1, respectively. These results were comparable to those of the membranes cast from PBI solutions in DMAc. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:Jingshuai Yang;Quantong Che;Xiaolei Gao ;Lili Shi
Polymer International 2010 Volume 59( Issue 12) pp:1695-1700
Publication Date(Web):
DOI:10.1002/pi.2906
Abstract
A novel copolymer of polybenzimidazoles was prepared by copolymerization of 3,3′-diaminobenzidine tetrahydrochloride, 3,4-diaminobenzoic acid and isophthalic acid in polyphosphoric acid at 200 °C. The polymerization could be performed within 90–110 min with the assistance of microwave irradiation. The solubility of the copolymer obtained in N,N-dimethylacetamide (DMAc) was improved compared with those of poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole] and poly(2,5-benzimidazole). Thus copolymer membranes could be readily prepared by dissolving the copolymer powders in DMAc with refluxing under ambient pressure. The decomposition temperature of the copolymer was about 520 °C in air according to thermogravimetric analysis data. The proton conductivity and mechanical strength of the phosphoric acid-doped copolymer membranes were investigated at elevated temperatures. A conductivity of 0.09 S cm−1 at 180 °C and a tensile stress at break of 5.9 MPa at 120 °C were achieved for the acid-doped copolymer membranes by doping acids in a 75 wt% H3PO4 solution. Copyright © 2010 Society of Chemical Industry
Co-reporter:Xu-Wei Chen, Lin-Lin Huang, Rong-Huan He
Talanta 2009 Volume 78(Issue 1) pp:71-75
Publication Date(Web):15 April 2009
DOI:10.1016/j.talanta.2008.10.039
Silk fibroin is a kind of polypeptide with functional amino acids in its structure. The electric charges in its molecular chains originating from the dissociation of acidic groups, i.e., hydroxyl, phenol and carboxyl, provide vast potentials for the retention of metal species of interest. In this study, the selective retention of Cu2+ with silk fibroin at pH 6.0 was investigated and a novel on-line procedure for separation/preconcentration of Cu2+ from complex sample matrices was thus developed by using a sequential injection system with an electrothermal atomic absorption spectrometry. A novel concept of enrichment index (EI), i.e., defined as enrichment factor (EF) obtained by consuming unity of sample volume (ml), was proposed for evaluating the enrichment efficiency of a flow-based preconcentration procedure. With a sampling volume of 900 μl, an EI of 30.3 (EF = 27.3) was achieved, which was much improved as compared to that of reported procedures. A detection limit of 8.0 ng l−1 was achieved within a linear range of 0.025–1.5 μg l−1 along with a precision of 2.2% R.S.D. at 0.5 μg l−1. The practical applicability of this procedure was validated by analyzing a certified reference material of riverine water (GBW08608) and a certified reference material of seawater (NASS-5) achieving satisfactory agreements between the certified and the obtained values. A spiking recovery was also performed by using a cave water sample.
Co-reporter:Ronghuan He;Quantong Che;Baoying Sun
Fibers and Polymers 2008 Volume 9( Issue 6) pp:679-684
Publication Date(Web):2008 December
DOI:10.1007/s12221-008-0107-0
The acid doping behavior of poly(2,2′-(m-phenylene)-5,5′-bibenzimidazole) (PBI) membranes in aqueous phosphoric acid was studied at room temperature. It was found that doping phosphoric acid in the membrane obeyed a multimolecular layer absorption mechanism proposed in this work. Equation, i.e., 1/[LT]B=(1 − C0/17.5)/2.1, was presented to describe the relationship of the acid doping level of membranes and the concentration of the doping acid in a range of 2–14 mol L−1. The acid doping kinetics as well as the influence of the doped acids on the conductivity and mechanical strength of the PBI membranes was investigated.
Co-reporter:Ronghuan He;Qingfeng Li;Jens Oluf Jensen;Niels J. Bjerrum
Journal of Polymer Science Part A: Polymer Chemistry 2007 Volume 45(Issue 14) pp:2989-2997
Publication Date(Web):4 JUN 2007
DOI:10.1002/pola.22053
Polybenzimidazole (PBI) membranes were doped in phosphoric acid solutions of different concentrations at room temperature. The doping chemistry was studied using the Scatchard method. The energy distribution of the acid complexation in polymer membranes is heterogeneous, that is, there are two different types of sites in PBI for the acid doping. The protonation constants of PBI by phosphoric acid are found to be 12.7 L mol−1 (K1) for acid complexing sites with higher affinity, and 0.19 L mol−1 (K2) for the sites with lower affinity. The dissociation constants for the complexing acid onto these two types of PBI sites are found to be 5.4 × 10−4 and 3.6 × 10−2, respectively, that is, about 10 times smaller than that of aqueous phosphoric acid in the first case but 5 times higher in the second. The proton conducting mechanism is also discussed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2989–2997, 2007
Co-reporter:Ming-Li Chen, Ai-Mei Zou, Yong-Liang Yu, Rong-Huan He
Talanta 2007 Volume 73(Issue 4) pp:599-605
Publication Date(Web):15 October 2007
DOI:10.1016/j.talanta.2007.04.037
The dominant role played by flow injection/sequential injection (FI/SI, including lab-on-valve, LOV) in automatic on-line sample pretreatments coupling to various detection techniques is amply demonstrated by the large number of publications it has given rise to. Among these, its hyphenation with hydride/vapor generation atomic fluorescence spectrometry (HG/VG-AFS) has become one of the most attractive sub-branches during the last years, attributed not only to the high sensitivity of this technique, but also to the superb separation capability of hydride/vapor forming elements from complex sample matrices. In addition, it also provides potentials for the speciation of the elements of interest.It is worth mentioning that quite a few novel developments of sample pretreatment have emerged recently, which attracted extensive attentions from the related fields of research. The aim of this mini-review is thus to illustrate the state-of-the-art progress of implementing flow injection/sequential injection and miniaturized lab-on-valve systems for on-line hydride/vapor generation separation and preconcentration of vapor forming elements followed with detection by atomic fluorescence spectrometry, within the period from 2004 up to now. Future perspectives in this field are also discussed.
Co-reporter:Yixin Xu, Niya Ye, Dengji Zhang, Jingshuai Yang, Ronghuan He
Journal of Colloid and Interface Science (1 July 2017) Volume 497() pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.jcis.2017.03.033
Two N3-substituted imidazoles 1,2-dimethylimidazole and 1-butyl-2-methylimidazole were chosen to functionalize poly(aryl ether ketone), respectively. The generated imidazolium cations could electrostatically react with sulfonate ions of the sulfonated poly(ether ether ketone) forming the ionic crosslinking structure of the membranes. The changes in crosslinking degree and the alkyl chain-length on N3 site of the imidazoliums could highly affect the properties of the anion exchange membranes (AEMs). The AEMs functionalized by 1-butyl-2-methylimidazole exhibited superior properties compared to those functionalized by 1,2-dimethylimidazole according to the tolerance tests of the AEMs towards hot alkaline solutions. After exposed to 1 M KOH at 80 °C for 200 h, the 1-butyl-2-methylimidazole modified AEMs maintained the ion exchange capacity of above 85%, the conductivity of about 70%, and the tensile stress at break of around 80%, respectively. The hydrophile-lipophile balance of the polymer membranes was calculated and proposed to better understand the correlation between structures and properties of the AEMs. The degradation of the imidazolium functional groups of the AEMs under the attack of hydroxide ions was evidenced by FT-IR analysis.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 20) pp:NaN5430-5430
Publication Date(Web):2013/08/05
DOI:10.1039/C3AY40845K
An imidazolium-containing sulfonated polyetheretherketone (SPEEK) composite, termed as SPEEK–Bmim, was prepared from SPEEK and 1-butyl-3-methylimidazolium hexafluorophosphate. This composite material was characterized by FT-IR, surface charge analysis and elemental analysis. The prepared material could selectively adsorb the protein hemoglobin (Hb). The adsorption efficiency was about 90%. The sorption capacity of the SPEEK–Bmim to Hb was 31.6 μg mg−1, and 84% of the retained Hb could be readily recovered by elution with 0.5% (m/v) aqueous sodium dodecyl sulfate (SDS) solution. The activity of the eluted Hb was about 91%. This ionic liquid-modified SPEEK composite was used practically for the isolation of Hb from human whole blood.
Co-reporter:Yang Zhang, Lu Han, Lin-Lin Hu, Yan-Qin Chang, Rong-Huan He, Ming-Li Chen, Yang Shu and Jian-Hua Wang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 30) pp:NaN5184-5184
Publication Date(Web):2016/07/11
DOI:10.1039/C6TB00987E
A pH and redox responsive bi-trigger continuous drug release nanocarrier is developed by capping mesoporous carbon nanoparticles (MCNs) with polyacrylic acid (PAA), termed as PAA-ss-MCN. The nanocarrier contains disulfide bond units and exhibits pH responsive behavior. It provides promising potential for drug loading due to the internal uniform channels and large surface area of MCNs. PAA grafted on the exterior surface of MCNs acts as a gating layer, generating a novel nano-container and a pH-responsive intelligent nanovalve. By loading doxorubicin (DOX) in PAA-ss-MCN, its sequential release is achieved via two approaches: (1) the intracellular acidic environment induces partial release from the surface of the PAA gating layer, (2) release of the drug sealed in nanochannels via disruption of the integrity of the nanocarrier by glutathione (GSH) caused dissociation of disulfide bonds in the physiological environment. As a result, release of 62% loaded drug is readily achieved. After culturing with HeLa cells, DOX transports into the cell interior and therein exhibits pH- and GSH-sensitive release. As most tumor sites exhibit more acidic environments or high redox potential, the pH- and GSH-sensitive releasing capability of PAA-ss-MCN is particularly useful for controllable drug delivery by taking advantage of the inherent characteristics of tumor cells.
Co-reporter:Jingshuai Yang, Qingfeng Li, Lars N. Cleemann, Chenxi Xu, Jens Oluf Jensen, Chao Pan, Niels J. Bjerrum and Ronghuan He
Journal of Materials Chemistry A 2012 - vol. 22(Issue 22) pp:NaN11195-11195
Publication Date(Web):2012/04/02
DOI:10.1039/C2JM30217A
Poly(aryl sulfone benzimidazole) (SO2PBI) and its copolymers with poly[2,2′-p-(phenylene)-5,5′-bibenzimidazole] (pPBI), termed as Co-SO2PBI, were synthesized with varied feeding ratios of 4,4′-sulfonyldibenzoic acid (SDBA) to terephthalic acid (TPA). Incorporation of the stiff para-phenylene and flexible aryl sulfone linkages in the macromolecular structures resulted in high molecular weight copolymers with good solubility. The chemical stability towards radical oxidation was improved for SO2PBI and its copolymer membranes due to the electron-withdrawing sulfone functional groups. Upon acid doping, the membrane swelling was reduced and the mechanical strength was improved, as compared with their meta structured analogues. At an acid doping level of 11 mol H3PO4 per average molar repeat unit, the Co-20%SO2PBI membrane exhibited a tensile strength of 16 MPa at room temperature and an H2-air fuel cell peak power density of 346 mW cm−2 at 180 °C at ambient pressure. Durability tests with the membrane under a constant current density of 300 mA cm−2 at 160 °C showed a degradation rate of 6.4 μV h−1 during a period of 2400 h, which was significantly lower than that for meta PBI membranes with a similar acid doping level.
![Poly[oxy(2,6-dimethyl-1,4-phenylene)]](http://img.cochemist.com/ccimg/25000/24938-67-8.png)
![Poly[oxy(2,6-dimethyl-1,4-phenylene)]](http://img.cochemist.com/ccimg/25000/24938-67-8_b.png)