Argon Plasma-Induced Graft Polymerization of PEGMA on Chitosan Membrane Surface for Cell Adhesion Improvement

For its biocompatibility and biodegradability, chitosan has had considerable atten- tion for biomedical applications in recent years. In this paper, polymerization of poly （ethylene glycol） methyl ether methacrylate （PEGMA） was grafted onto chitosan membrane surface through argon plasma-induced graft polymerization. The surface properties after modification were characterized by contact angle measurement, X-ray photoelectron spectroscopy （XPS） and atomic force microscopy （AFM）, respectively. The results indicated that PEGMA can be grafted successfully onto chitosan membrane surface. The surface hydrophilicity and free energy were improved and the surface roughness increased after modification. The adhesion of a human corneal epithelial cell （HCEC） on chitosan membrane surface was enhanced due to improvement of surface free energy and roughness.

Effect of sodium alginate/phosphate-stabilized amorphous calcium carbonate nanoparticles on chitosan membranes

Biodegradable chitosan(CS)films can meet the demand for sustainable development.However,the performance of pure CS membrane still exists a particular gap compared with the traditional film.Inorganic nanomaterials with the controllable release are added to improve its physical and chemical properties.Herein,a series of CS/phosphate-stabilized amorphous calcium carbonate(CS/ACCP)and CS/sodium alginate/ACCP(CS/Alginate/ACCP)composite films were prepared by the flow method.The effects of ACCP and Alginate/ACCP nanoparticles on the physical and chemical properties of the composite membrane were investigated.The results showed that the composite nanoparticles could significantly improve CS film’s compactness,hydrophobicity,and mechanical properties and enhance its ultraviolet(UV)blocking ability,water resistance,and water vapor blocking ability.When the number of nanoparticles was 8%,the mechanical properties of the CS composite membrane reached optimum value,and the comprehensive performance was better.In addition,the controlled-release properties of CS composite membranes were also studied,and the antioxidant,antibacterial,biocompatibility,and fresh-keeping effects of the composite membranes were explored.The results indicated that the CS composite membranes had not only excellent bacteriostatic(72%)properties(Escherichia coli)but also presented well fruit preservation(15 days)properties(sugar orange).In particular,the controlled release range of CS composite membrane at 12 h was between 30%and 90%,which provided a theoretical basis for its use as an edible membrane.Therefore,based on ACCP and Alginate/ACCP nanoparticles,CS composite membranes with more excellent application value in the biological field were prepared through further optimization design.

Preparation of Thermal-responsive Chitosan-graft-N-isopropyl- acrylamide Membranes via γ-Ray Irradiation

A novel thermo-sensitive switching membrane has been prepared by radiation-induced simultaneous grafting N-isopropylacrylamide （NIPAAm） onto chitosan membrane. Fourier transform infrared spectroscopy （FTIR） was used to identify the structure of the grafted membranes. The surface morphology of the grafted membrane was observed from scanning electron microscopy （SEM）. Pure water flux measurements showed that water flux of the grafted membrane decreased with the increase of temperature, while that of chitosan membrane was constant. It was proved that grafted membrane was sensitive to temperature.

STUDIES ON THE SELF-DIFFUSION OF WATER ETHANOL MIXTURE IN CHITOSAN PERVAPORATION MEMBRANE WITH PULSED FIELD GRADIENT NMR DATA

The self-diffusion of water, ethanol and water-ethanol mixtures in chitosan (CS) membranes crosslinked by aqueous H2SO4 solution and uncrosslinked membrane was measured using pulsed-field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy to obtain the partial solubilities and self-diffusion coefficients. An attempt was made to explain the transport properties of water and ethanol through the CS membrane. It was concluded that there are two types of channel water and ethanol diffusate transfer. The water was localized in the hydrophilic ionic region formed by the ionized groups, and the ethanol was localized in the hydrophobic amorphous network of the polymer. There was a good agreement between. the separation factors estimated from PFG-NMR data and those obtained by pervaporation testing.

Extended adsorption transport models for permeation of copper ions through nanocomposite chitosan/polyvinyl alcohol thin affinity membranes

Transport of copper ions through nanocomposite chitosan/polyvinyl alcohol thin adsorptive membranes has been mathematically investigated in the current study. Unsteady-state diffusive transport model was coupled with the Freundlich isotherm to predict the concentration of the ions in dialysis permeation operation. Pristine model was not successful in predicting the experimental data based upon its low coefficients of determination（0.1

Preparation and Blood Compatibility of Oxidized-chitosan Films

Chitosan membrane was modified by the selective oxidization of chitosan molecules on its surface with NO2 gas. FTIR spectra indicated there were plenty of –COOH and –COO- groups on the modified membrane surface. The SEM study showed the modified membrane surface was rough rather than smooth as chitosan membrane. All antithrombosis test, hemolysis test and blood cell morphology observation with SEM revealed that modified chitosan membranes have superior blood compatibility to chitosan.

用于废水净化的壳聚糖膜改性技术研究进展

壳聚糖是一种具有生物相容性、无毒性、抑菌性等诸多优良性能的成膜材料,吸附性的壳聚糖微滤(MF)膜和超滤(UF)膜已在废水污染物的分离方面展示出巨大的应用潜力。但是,壳聚糖膜的机械性能较差、遇酸易水解等缺点限制了它的应用范围。基于壳聚糖分子表面含有丰富的羟基、氨基等活性基团而易于改性的特点,近年来研究人员采用多种方法改变壳聚糖的化学组成及其表面性质,以便使壳聚糖膜适合特定的应用需要。对在废水处理领域有特殊应用的5种改性壳聚糖膜(交联壳聚糖膜、壳聚糖季铵盐复合膜、壳聚糖共混膜、有机-无机杂化壳聚糖膜、香草醛改性壳聚糖膜)的制备方法、原理和应用效果进行了综述,并提出了进一步研究的方向。

Inhibitory effect of three biopolymer materials on scar formation following trabeculectomy

AIM: To investigate the inhibitory effects of amniotic membrane, polylactic acid membrane and chitosan membrane on scar formation following trabeculectomy. METHODS: A total of 24 New Zealand white rabbits (48 eyes) were randomly divided into 4 groups: amniotic membrane group, polylactic acid membrane group, chitosan membrane group, and control group, with 6 rabbits (12 eyes) in each group. The left eyes underwent routine trabeculectomy, and the right eyes were considered as controls. Amniotic membrane, polylactic acid membrane and chitosan membrane were respectively installed under sclera flap in three groups, but any treatment was not applied in control group. Intraocular pressure, conjunctival filtering bleb, and anterior chamber inflammation responses were monitored at day 1, 3, 7, 14, 28 and 56 post-operatively. Eyeball tissue underwent histopathological examination at day 56 post-operatively. RESULTS: Fibrocytes and inflammatory cells were reduced in amniotic membrane, polylactic acid membrane and chitosan membrane groups compared to that in control group. At day 1 post-operatively, intraocular pressure was decreased in three membrane groups compared to that in control group. At day 14 post-operatively, the intraocular pressure was decreased significantly, while it of three membrane groups was significantly lower than that of preoperative (P<0.01). There were no significant differences among three membrane groups (P>0.05). Filtering bleb of four groups was clearly observed at day 7 post-operatively, but there was no significant difference in pair-wise comparison. At day 28 and 56 post-operatively, filtering bleb in control group was significantly narrowed compared to that in three membrane groups (P <0.05), but there was no significant difference in pair-wise comparison of three membrane groups. CONCLUSION: All amniotic membrane, polylactic acid membrane and chitosan membrane can effectively inhibit scar formation following trabeculectomy, the effect of amniotic membrane is the best.

PREPARATION OF CHITOSAN/HYDROXYAPATITE GUIDED MEMBRANE USED FOR PERIODONTAL TISSUE REGENERATION

In an effort to develop biomaterials to meet guided tissue regeneration （GTR） standards for periodontal tissue recovery, a homogeneous and transparent chitosan （CS）/hydroxyapatite （HA） membrane with potential applications as GTR barrier in periodontal therapy has been prepared via in situ compositing. The membrane has been designed to have a smoothrough asymmetric structure that meets the demand for GTR. Component and morphology of the membrane are characterized by XRD and SEM. It can be indicated that HA was in situ synthesized uniformly in the CS membrane. Mechanical experiments of the membranes with various HA contents show that their tensile strengths are adequate for periodontal therapy. Biological properties of the membrane have been performed by cell toxicity assays, hemolysis tests and animal experiments. Results indicate that the membrane has good biocompatibility and inductive effect for cell growth. Therefore this membrane can be potentially applied as GTR barrier membrane for periodontal tissue regeneration.

On-Chip Fabrication of Carbon Nanoparticle–Chitosan Composite Membrane

The on-chip fabrication of a carbon nanoparticle-chitosan composite membrane （i.e. a sorbent membrane or a mixed matrix membrane） using laminar flow-based interfacial deprotonation technology was presented in this paper. In addition, the effects of carbon nanoparticles and reactant flow rates on membrane formation were investigated. Finally, the permeability and adsorption capacities of the membrane were discussed. During fabrication, an acidic chitosan solution and a basic buffer solution that contained carbon nanoparticles were introduced into a microchannel. At the flow interface, a freestanding composite membrane with embedded carbon nanoparticles was formed due to the deprotonation of the chitosan molecules. The membrane growth gradually stopped with time from upstream to downstream and the thickness of the membrane increased rapidly and then slowly along the reactant flow direction. The formation of the membrane was divided into two stages. The average growth rate in the first stage was significantly larger than the average growth rate in the second stage. Carbon nanoparticles in the basic solution acted as nucleating agents and made the membrane formation much easier. As the flow rate of the chitosan solution increased, the averaged membrane thickness and the membrane hydraulic permeability initially increased and then decreased. Because of the addition of carbon nanoparticles, the formed membrane had adsorption abilities. The carbon nanoparticle-chitosan composite membrane that was fabricated in this study could be employed for simultaneous adsorption and dialysis in microdevices in the future.

Artificial neuron synapse transistor based on silicon nanomembrane on plastic substrate

Silicon nanomembrane（SiNM）transistors gated by chitosan membrane were fabricated on plastic substrate to mimic synapse behaviors.The device has both a bottom proton gate（BG）and multiple side gates（SG）.Electrical transfer properties of BG show hysteresis curves different from those of typical SiO2 gate dielectric.Synaptic behaviors and functions by linear accumulation and release of protons have been mimicked on this device：excitatory post-synaptic current（EPSC）and paired pulse facilitation behavior of biological synapses were mimicked and the paired-pulse facilitation index could be effectively tuned by the spike interval applied on the BG.Synaptic behaviors and functions,including short-term memory and long-term memory,were also experimentally demonstrated in BG mode.Meanwhile,spiking logic operation and logic modulation were realized in SG mode.

Chitosan-DNA microparticles as mucosal delivery system: synthesis, characterization and release in vitro

Background Mucosal immunity is important to defense against dental caries. To enhance mucosal immunity, a DNA vaccine mucosal delivery system was prepared by encapsulating anticaries DNA vaccine (plasmid pGJA-P/VAX) in chitosan under optimal conditions and the characteristics of the microparticles was investigated. Furthermore, the release properties and protective action of microparticles for plasmid were studied in vitro.Methods Plasmid loaded chitosan microparticles were prepared by complex coacervation. Three factors, concentration of DNA, sodium sulfate, and the chitosan/DNA ratios in complexes [better expressed as N/P ratio: the number of poly nitrogen (N) per DNA phosphate (P)] influencing preparation were optimized by orthogonal test. The characteristics of microparticles were evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). DNA release rate of microparticles in similar gastro fluid (SGF) or similar intestinal fluid (SIF) at 37℃ was determined by ultraviolet spectrophotometry.Results High encapsulation efficiency (96.8%) was obtained with chitosan microparticles made under optimal conditions of 50 mmol/L Na2SO4, 200 μg/ml DNA and N/P ratio of 4. The size of particles was about 4 to 6 μm. The encapsulation process did not destroy the integrity of DNA. When incubated with SIL, after a release of about 10% in the first 60 minutes, no further DNA was released during the following 180 minutes. When incubated with SGL, the microparticles released a small burst (about 11%) in the first 60 minutes, and then slowly released at a constant, but different rate.Conclusions These chitosan microparticles showed suitable characteristics in vitro for mucosal vaccination and are therefore a promising carrier system for DNA vaccine mucosal delivery.

Purification,characterization and application of dual coagulants containing chitosan and different Al species in coagulation and ultrafiltration process

The objective of this study was to investigate the effect of different Al species and chitosan（CS） dosages on coagulation performance,floc characteristics（floc sizes,strength and regrowth ability and fractal dimension） and membrane resistance in a coagulation-ultrafiltration hybrid process.Results showed that different Al species combined with humic acid in diverse ways.A1_a had better removal efficiency,as determined by UV_（254） and dissolved organic carbon,which could be further improved by the addition of CS.In addition,the optimal dosage of different Al species was determined to be 4.0 mg/L with the CS concentration of 1.0 mg/L,by orthogonal coagulation experiments.Combining Al_a/A1_b/A1_c,with CS resulted in larger flocs,higher recovery,and higher fractal dimension values corresponding to denser flocs;in particular,the floc size at the steady state stage was four times larger than that obtained with Al species coagulants alone.The results of ultrafiltration experiments indicated that the external fouling percentage was significantly higher than that of internal fouling,at around 85%and 15%,respectively.In addition,the total membrane resistance was significantly decreased due to CS addition.