Search for cost-effective and high-strength dye adsorbents has become an urgent problem in wastewater treatment. Natural polymers such as chitosan and cellulose are low-cost and can be fabricated as hydrogels for dye adsorption, but these hydrogels usually have weak strength. Here, novel high-strength and highly cost-effective hydrogels with a high capacity of dye adsorption were prepared with chitosan and cellulose. The chitosan/cellulose hydrogels could be knotted and twisted without fracture and could be restore rapidly after compression. These features showed that the hydrogels had good elasticity, high strength and excellent resilience. Also, the incorporation of rectorite into hydrogels could increase the thermal stability and strength of composite hydrogels. Subsequently, the adsorption capacity of hydrogels to Congo Red was investigated: chitosan was the main functional material for adsorption and rectorite participated in dye adsorption as well, but cellulose supported the structure. Furthermore, the adsorption process fitted closely with the Freundlich model, and was best described by a pseudo-second-order kinetic model. The hydrogels were biodegradable and could be easily collected after adsorption. These environmental friendly hydrogels could be promising candidates for dye removal in the future.

•Coating machine is used to process layer-by-layer deposited nanofibrous mats.•Planar effect on the surface of mats can be eliminated through immersion.•The combined methods can result in thick and uniform bilayers.•LBL-deposited nanofibrous mats remains the unique three-dimensional structure.When an efficient automated coating machine is used to process layer-by-layer (LBL) deposited nanofibrous mats, it causes an obvious planar effect on the surface of the mats, which can be eliminated through ultimate immersion. During this process, chitosan (CS) − rectorite (REC) intercalated composite films are built on the surface of cellulose acetate (CA) nanofibrous mats by a coating machine. Then, the immersion process is utilized to allow positively charged CS or CS-REC intercalated composites to uniformly assemble on the surface of negatively charged CA nanofibers. An investigation into the morphology of the resultant scaffolds confirms that the uniquely small pore size, high specific surface area and typically three-dimensional (3D) structure of nanofibrous mats remain present. The results of Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) indicate that it is feasible to assemble nanofibrous mats using a coating machine. The intercalated structure of CS-REC is confirmed by the results of small-angle X-ray diffraction (SAXRD) and wide-angle X-ray diffraction (WAXRD). The results of the cell experiment and antibacterial test demonstrate that the addition of REC not only has little impact on the cytocompatibility of the mats but also enhances their ability to inhibit bacteria.The production of thick-uniform coating films on nanofibers through automated coating machine and immersion.

Self-assembled nanoparticles (NPs) composed of chitosan (CS) and low density lipoprotein (LDL) of hen eggs were prepared by a one-step green synthesis of mixing CS solution and LDL suspension. The formulated CS-LDL NPs were then applied to encapsulate doxorubicin hydrochloride (DOX) with the encapsulation efficiency of 51.7%. The average particle size and ζ-potential of DOX-loaded CS-LDL NPs (CS-LDL-DOX NPs) were 179 nm and +48.3 mV, respectively. The encapsulated DOX showed less cytotoxicity than free DOX after 24-h incubation with gastric cancer SGC7901 cells, which may be due to extended release. Cellular uptake of CS-LDL-DOX NPs was significant higher than that of free DOX due to the endocytosis of tumor cells. Thus CS-LDL-DOX NPs showed a potential in reducing cytotoxicity of DOX by extended release behavior and preferential uptake compared to free DOX. In addition, flow cytometry and terminal-deoxynucleotidyl-transferase-mediated dUTP nick-end labeling assay demonstrated that CS-LDL-DOX NPs induced the apoptosis of cancer cells. Autophagy was involved in effects caused by CS-LDL-DOX NPs through blocking AKT/mTOR signaling, which was demonstrated by the analyses of the expression of LC3, p62, AKT, p-AKT, mTOR and p-mTOR.Download high-res image (255KB)Download full-size image

•Nanofibers were deposited with bilayer of CS/EGCG or CS-REC/EGCG via LBL technique.•The addition of REC improved EE and LC of EGCG onto nanofibers.•The addition of REC facilitated sustained release of EGCG from nanofibers.•(CS/EGCG)n- and (CS-REC/EGCG)n-coated cellulose nanofiber had antimicrobial effect.•The addition of REC enhanced the inhibition of CS and EGCG on bacterial growth.Cellulose electrospun nanofibrous mats coated with bilayers of chitosan (CS) and epigallocatechin gallate (EGCG) or with bilayers of CS-rectorite (REC) composite (CS-REC) and EGCG were fabricated via layer-by-layer (LBL) self-assembly technique. LBL-structured cellulose nanofibers still maintained three-dimension fiber structure according to the observation from scanning electron microscopy images. The average diameter of nanofibers were enlarged with the addition of REC. X-ray photoelectron spectroscopy results confirmed the deposition of CS and CS-REC onto the corresponding mats. The tensile strength and rate of elongation at break of LBL-structured nanofibers had no difference from those of uncoated nanofibers. The encapsulation efficiency and loading capacity of nanofibers were enhanced in the presence of REC. In addition the in-vitro cumulative release profiles of EGCG indicate that the addition of REC delayed the release of EGCG. Antimicrobial assay demonstrated the inhibitory effects of CS and EGCG on the growth of Staphylococcus aureus. Meanwhile the CS-REC composites improved the antimicrobial effects of CS and EGCG by adsorption of bacteria to the surface of REC then enhancement of exposure of bacteria to EGCG and the matrix of CS.

•Chitosan was modified into quaternized carboxymethyl chitosan.•Rectorite was modified by SDS into organic rectorite.•The OREC based intercalated nanofibrous mats were fabricated.•LBL self-assembly technique was applied.Quaternized carboxymethyl chitosan (QCM-chitosan) and organic rectorite (OREC) immobilized nanofibrous mats are fabricated via layer-by-layer (LBL) technique in a self-assembly manner. The negatively charged cellulose nanofibrous mats hydrolyzed from electrospun cellulose acetate (CEL) mats are alternately modified with the positively charged QCM-chitosan and OREC intercalated composites and the negatively charged sodium alginate (ALG) via LBL technique. The morphology and antibacterial activity of the resultant mats are studied by changing the number of deposition bilayers, the compositions of dipping solutions and outermost layer. X-ray photoelectron spectroscopy results imply that QCM-chitosan and OREC are coated on cellulose mats. Besides, wide angle X-ray diffraction and small angle X-ray diffraction are applied to investigate the crystalline of the composite mats and the interlayer distance of OREC, respectively. The antibacterial activity of the mats increases with the incorporation of OREC into LBL films.

•Both LBL and electrospinning technique were applied.•LZ and pectin were alternately deposited on the surface of cellulose mats.•Better antibacterial activity was achieved after LBL deposition.Positively charged lysozyme (LZ) and negatively charged pectin, were alternately deposited on the surface of the cellulose nanofibrous mats by layer-by-layer (LBL) self-assembly technique. Scanning electron microscopy images showed that the nanofibers were orderly and compactly arrayed after LBL. Besides, as the number of LZ/pectin bilayers increased, the average diameter of nanofibers increased. LZ has assembled on the cellulose mats successfully, which was confirmed by X-ray photoelectron spectroscopy analysis. Thermal gravimetric analysis results showed that the thermal properties of LZ/pectin films coated mats was better than that of the unmodified cellulose mats. Importantly, the results of the bacterial inhibition test for LBL structured mats and cellulose mats indicated that the nanofibrous mats coated by 10.5 LZ/pectin bilayers (with LZ on the outmost layer) possessed the strongest inhibitory effect against both Escherichia coli and Staphylococcus aureus.

•HTCC and SPI were alternately deposited on CA mats via LBL self-assembly technique.•HTCC/SPI-bilayer-modified CA mats possessed antimicrobial activity.•Antimicrobial effects positively correlated with number of bilayers on CA mats.•HTCC on the outermost layer of mats enhanced the antimicrobial effects.Positively charged N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC) and negatively charged soy protein isolate (SPI) were alternately assembled on cellulose acetate (CA) electrospun nanofibrous mats via electrostatic layer-by-layer self-assembly technique. CA nanofibrous mats coated with bilayers of HTCC and SPI possessed more orderly-arranged structure than uncoated CA mats according to the observation from scanning electron microscopy images. The average diameter of the nanofibers was enlarged by the increase of the bilayer number. X-ray photoelectron spectroscopy indicated that HTCC and SPI were coated on the surface of the CA mats successfully. The average diameters of inhibition zones of (HTCC/SPI)10.5-films-coated nanofibrous mats against Escherichia coli and Staphylococcus aureus were 9.6 mm and 11.53 mm, respectively, which demonstrated the highest antimicrobial activity among samples in presented study.

•LY/ALG-REC NGs assembled cellulose nanofibrous mats were successfully prepared.•The prepared materials exhibited excellent antibacterial capacity.•The immobilization of NGs onto mats facilitated the survival rate of cells.•The addition of REC facilitated antibacterial capacity and cell compatibility.Rectorite (REC)-encapsulated lysozyme (LY)-alginate (ALG) nanogels (NGs) were prepared by adding ALG-REC composites suspensions into LY solutions at the mass ratio of 1:2. The morphology of the NGs and the NGs-assembled nanofibrous mats were studied by transmission electron microscope and field emission scanning electron microscopy, respectively. The composition of NGs-immobilized nanofibrous mats was detected by X-ray photoelectron spectroscopy. The NGs-assembled nanofibrous mats with the addition of REC could enhance the inhibition against Escherichia coli and Staphylococcus aureus. Additionally, NGs-coated mats reduced the toxicity of cellulose mats on mouse lung fibroblasts using MTT assay. Besides, the addition of REC in the NGs improved the cell compatibility of NGs-assembled nanofibrous mats.

Alginate (ALG)–lysozyme (LZ) beads were fabricated by a cross-linking process. Negatively charged ALG and positively charged LZ were alternately deposited on the positively charged ALG–LZ beads via layer-by-layer (LBL) self-assembly technique. The mechanical properties and the enzymatic activity of these samples were studied by regulating the number of deposition bilayers and the composition of the outermost layer. The scanning electron microscopy images indicated that the resultant samples exhibited good sphericity and porosity. The Fourier transform infrared spectra results implied the presence of electrostatic interactions between ALG and LZ. The pore size distribution results revealed that the samples mainly possessed mesopores with radius in the range of 2–7 nm. In vitro LZ release test performed at different time intervals showed that LZ could be released from ALG–LZ beads and LBL film-coated beads. The amount of released LZ increased with extended time intervals.

•Surface morphology and surface chemical composition of the samples were tested.•The assembled films had good antimicrobial activities.•Release profiles of the antimicrobials under different conditions were studied.In this study, polyethylene terephthalate/polypropylene (PET/PP) films were treated via atmospheric pressure plasma, assembled with chitosan and various preservatives and applied for antimicrobial food packaging. Surface properties of these obtained films were studied by contact angle measurement, atomic force microscopy (ATM), X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared spectroscopy (FT-IR) and dynamic laser scattering (DLS). The above results showed that the surface hydrophilicity and roughness of the films increased after the plasma treatment. Besides, chitosan and the preservatives were successfully assembled onto the surface of the films. In addition, the antimicrobial activities of the films against three kinds of microorganisms (Staphylococcus aureus, Bacillus subtilis and Escherichia coli) were investigated and the results indicated that the inhibition ratios against B. subtilis and E. coli reached almost 100% while the inhibition ratios against S. aureus were lower than 85%. Moreover, the accumulative release profiles of the antimicrobial substances migrating from the assembled films into the release solutions revealed that their release speed increased with the increment of temperature and acidity, but decreased with enhancing the ionic strength regulated by sodium chloride or with lowering the ionic mobility regulated by sucrose.

•Chitosan-layered silicates protect cells against the Pb2+ induced toxicity.•Cell viability of PC12 significantly increased after adding the composites.•The pathways of their inhibitory effect have been investigated.Protecting cells from toxicosis even apoptosis induced by a variety of toxic heavy metals stimulus has drawn more and more attentions. This study was designed to elucidate whether chitosan-organic rectorite (CS-OREC) composites exhibited any protective effects on altered oxidative stress parameter in PC12 cells exposed to lead ions (Pb2+). The cells were exposed to Pb2+ either alone or in combination with CS-OREC composites for designated time to evaluate the efficacy of the composites on Pb2+-induced toxicity. The MTT assay results showed that the cell viability of PC12 was remarkably decreased when exposed to Pb2+, but significantly retained after adding CS-OREC composites compared to that of the control. The beneficial effect of CS-OREC composites on cytotoxicity was related, at least in part, to its ability to protect against apoptosis in PC12 cells exposed to 50 μM Pb2+. Their protective effect was also associated with the inhibitory effect on Pb2+-induced activation of Bax/Bcl-2, P-38, and caspase-3 pathways, while was independent on JNK pathway.

•Fe3O4/GO/Chitosan microspheres were prepared via an electrospray method.•Fe3O4 confers magnetic properties to the microsphere.•GO enhances the DOX loading capacity of the microsphere.•Remote controlled DOX release was induced by NIR or Ultrasound irradiation.The construction of multifunctional microspheres for remote controlled drug release requires the exquisite selection of composite materials and preparation approaches. In this study, chitosan, an amino polysaccharide, was blended with inorganic nanocomponents, Fe3O4 and graphene oxide (GO) and electrosprayed to fabricate uniform microspheres with the diameters ranging from 100 μm to 1100 μm. An anti-cancer drug, doxorubicin (DOX), was loaded to the microspheres by an adsorption or embedding method. The microsphere is responsive to magnetic fields due to the presence of Fe3O4, and the incorporation of GO enhanced the drug loading capacity. The fast stimuli-responsive release of DOX can be facilely controlled by using NIR irradiation due to the strong photo-thermal conversion of Fe3O4 and GO. In addition, ultrasound was used as another external stimulus for DOX release. The results suggest the Fe3O4/GO/Chitosan microspheres fabricated by the electrospray method provide an efficient platform for remote controlled drug release, which may have potential applications in drug eluting microspheres.A remote controlled release of DOX from the electrosprayed Fe3O4/Graphene oxide/Chitosan microspheres was triggered by the irradiation of ultrasound or Near Infrared light.