The kinetic inhibiting effect of a number of chitosans on hydrate formation was investigated using methane and methane/ethane gas mixtures.The results indicated that chitosan was a good kinetic inhibitor.The induction...The kinetic inhibiting effect of a number of chitosans on hydrate formation was investigated using methane and methane/ethane gas mixtures.The results indicated that chitosan was a good kinetic inhibitor.The induction time of gas hydrate formation evidently increased with the degree of deacetylation （DD）,however,when DD was higher than 80%,the effect of DD on the induction time was negligible.Moreover,it was found that the molecular weight （MW） of chitosan and the addition of polyethylene oxide （PEO） had little effect on the induction time.The optimal concentration of chitosan was found to be 0.6 wt%.Finally,the mechanisms of the kinetic inhibitor on the hydrate formation were discussed.展开更多
Background:LL-37 peptide is a member of the human cathelicidin family,and has been shown to promote the healing of pressure ulcers.However,the low stability of this peptide within the wound environment limits its clin...Background:LL-37 peptide is a member of the human cathelicidin family,and has been shown to promote the healing of pressure ulcers.However,the low stability of this peptide within the wound environment limits its clinical use.Chitosan(CS)hydrogel is commonly used as a base material for wound dressing material.Methods:CS hydrogel(2.5%w/v)was encapsulated with LL-37.Cytotoxicity of the product was examined in cultured NIH3 T3 fibroblasts.Effects on immune response was examined by measuring tumor necrosis factor-α(TNF-α)release from RAW 264.7 macrophages upon exposure to lipopolysaccharides.Antibacterial activity was assessed using Staphylococcus aureus.Potential effect on pressure ulcers was examined using a mouse model.Briefly,adult male C57 BL/6 mice were subjected to skin pressure using magnets under a 12/12 h schedule for 21 days.Mice were randomized to receive naked LL-37(20μg),chitosan gel containing 20μg LL-37(LL-37/CS hydrogel)or hydrogel alone under the ulcer bed(n=6).A group of mice receiving no intervention was also included as a control.Results:LL-37/CS hydrogel did not affect NIH3 T3 cell viability.At a concentration of 1–5μg/ml,LL-37/CS inhibited TNF-αrelease from macrophage.At 5μg/ml,LL-37/CS inhibited the growth of Staphylococcus aureus.The area of the pressure ulcers was significantly lower in mice receiving LL-37/CS hydrogel in comparison to all other 3 groups on days 11(84.24%±0.25%),13(56.22%±3.91%)and 15(48.12%±0.28%).Histological examination on days 15 and 21 showed increased epithelial thickness and density of newly-formed capillary with naked LL-37 and more so with LL-37/CS.The expression of key macromolecules in the process of angiogenesis(i.e.,hypoxia inducible factor-1α(HIF-1α)and vascular endothelial growth factor-A(VEGF-A))in wound tissue was increased at both the mRNA and protein levels.Conclusion:Chitosan hydrogel encapsulated with LL-37 is biocompatible and could promote the healing of pressure ulcers.展开更多
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...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.展开更多
Poor cycling performance caused by the shuttle effect of polysulfides is the main obstacle in the development of advanced lithium-sulfur(Li-S)batteries.Functional polymer binders with polar groups can effectively adso...Poor cycling performance caused by the shuttle effect of polysulfides is the main obstacle in the development of advanced lithium-sulfur(Li-S)batteries.Functional polymer binders with polar groups can effectively adsorb polysulfides chemically,thereby suppressing the shuttle effect.Herein,a robust three-dimensional crosslinked polymer network,which demonstrates excellent mechanical property and strong affinity for polysulfides,is prepared by the aldimine condensation and coordination reactions.The crosslinked chitosan sulfate network(CCSN)significantly enhances the cycling performance and rate capability of the sulfur cathode.The CCSN-based sulfur cathode exhibits a high initial discharge capacity of 824 m Ah g^(-1) with only 0.082%average capacity loss per cycle at 1 C.At a high rate of 4 C,the cathode exhibits a high capacity retention of 84.8%after 300 cycles.Moreover,the CCSN-based sulfur cathode exhibits an excellent cycling performance at a high sulfur loading of 2.5 mg cm^(-2),which indicates the excellent mechanical strength and binding performance of the CCSN binder for high-energy density Li-S batteries.This study demonstrates a viable approach for developing high-performance Li-S batteries for practical application.展开更多
In this paper, a novel and sensitive electrochemical aptasensor for detecting tetracycline(TET)with prussian blue(PB) as the label-free signal was fabricated. A PB-chitosan-glutaraldehyde(PB-CS-GA)system acting as the...In this paper, a novel and sensitive electrochemical aptasensor for detecting tetracycline(TET)with prussian blue(PB) as the label-free signal was fabricated. A PB-chitosan-glutaraldehyde(PB-CS-GA)system acting as the signal indicator was developed to improve the sensitivity of the electrochemical aptasensor.Firstly, the PB-CS-GA was fixed onto the glass carbon electrode surface. Then, colloidal gold nanoparticles(Au NPs) were droped onto the electrode to immobilize the anti-TET aptamer for preparation of the aptasensor.The stepwise assembly process of the aptasensor was characterized by cyclic voltammetry(C-V) and scanning electron microscope(SEM). The target TET captured onto the electrode induced the current response of the electrode due to the non-conducting biomoleculars. Under the optimum operating conditions, the response of differential pulse voltammetry(DPV) was used for detecting the concentration of TET. The proposed aptasensor showed a high sensitivity and a wide linear range of 109-～ 105-M and 105-～ 102-M with the correlation coefficients of 0.994 and 0.992, respectively. The detection limit was 3.2×1010-M(RSD 4.12%). Due to its rapidity, sensitivity and low cost, the proposed aptasensor could be used as a pre-scanning method in TET determination for the analysis of livestock products.展开更多
A novel porous nanocomposite,cross-linked chitosan and polyethylene glycol(PEG) bead-supported MnFe_(2) O_(4) nanoparticles(CPM),was developed as an efficient adsorbent to remove metalloid(As(Ⅲ))and heavy metals(Cd(...A novel porous nanocomposite,cross-linked chitosan and polyethylene glycol(PEG) bead-supported MnFe_(2) O_(4) nanoparticles(CPM),was developed as an efficient adsorbent to remove metalloid(As(Ⅲ))and heavy metals(Cd(Ⅱ),Cu(Ⅱ),and Pb(Ⅱ)).The characteristics of CPM showed a porous structure,well dispersed MnFe_(2) O_(4),and several of hydroxyl and amino groups(-OH,-NH_(2)).Batch experiments demonstrated that the best adsorption property of As(Ⅲ),Cd(Ⅱ),Cu(Ⅱ),and Pb(Ⅱ) was achieved within 8 h with maximum adsorption capacities of 9.90,9.73,43.94,and 11.98 mg/g,respectively.Competitive and synergistic effects(particularly precipitation) were included in the co-adsorption mechanism of As(Ⅲ) and heavy metals.Thereinto,As(Ⅲ) was partly oxidized by MnFe_(2) O_(4) to As(V),and both were coordinated on MnFe_(2) O_(4) nanoparticles.Pb(Ⅱ) could also bind to MnFe_(2) O_(4) by ion exchange and electrostatic attraction.Furthermore,Cd(Ⅱ) and Cu(Ⅱ) tended to be coordinated on chitosan.Therefore,CPM can serve as a remediation material for water and soil co-contaminated with As(Ⅲ) and heavy metals.展开更多
Pulsed discharge plasma has exhibited active potential to prepare low molecular weight chitosan. In the present study, the viscosity of ehitosan solution was decreased noticeably after treated with pulsed corona disch...Pulsed discharge plasma has exhibited active potential to prepare low molecular weight chitosan. In the present study, the viscosity of ehitosan solution was decreased noticeably after treated with pulsed corona discharge plasma. An experimental investigation on electrical characteristics of pulsed corona discharge plasma in chitosan solution was conducted with a view toward getting insight into discharge process. Factors affecting I-V curve, single pulse injec- tion energy and pulse width were studied. Experimental results showed positive effect of pulsed peak voltage on discharge plasma in chitosan solution. Pulse-forming capacitor greatly influenced the discharge form, and 4 nF was observed as a suitable value for efficiently generating stable discharge plasmas. As the electrode distance was larger than 10 ram, it had slight impact on dis- charge plasma due to the excellent conductive-property of chitosan solution. The injection energy significantly increased with air flow rate, while the pulse width hardly changed as the air flow rate increased from 0.5 m^3/h to 1.0 m^3/h. This study is expected to provide reference for promoting the application of pulsed corona discharge plasma to ehitosan solution treatment.展开更多
Recently, chitosan nanoparticles have been an attractive biomaterial for their unique properties. Chitosan nanoparticles are mainly used as drug delivers. However, they are seldom used in wound healing after severe bl...Recently, chitosan nanoparticles have been an attractive biomaterial for their unique properties. Chitosan nanoparticles are mainly used as drug delivers. However, they are seldom used in wound healing after severe bleeding. In the present paper, chitosan nanoparticles with an average size of 60.2 nm were prepared through ionic gelation and characterized by X-ray diffraction and FT-infrared spectrometry. A new animal model of severe bleeding was made to evaluate its effects on wound healing besides hemostasis. The results showed that it can achieve well hemostatic effects and also induce wound healing after severe bleeding. Blood cells can be absorbed by chitosan nanoparticles and the bleeding is treated. Furthermore, the chitosan nanoparticles sustains longer than other materials in wound healing. At the 15th day after operation, the chitosan nanoparticles with the size of 58.3 nm can still be seen in the new-regenerated hepatic tissue. It can induce the formation of a clear granulation around the wound site. Through histological observation, we find out that chitosan-TPP nanoparticles can induce wound healing through migration of the inflammatory cells and synthesis of collagen. So, chitosan nanoparticles show us both hemostasis and the ability of wound healing for parenchymal organs.展开更多
Nickel ferrite(NiFe_2O_4) nanoparticles have been dispersed in chitosan solution in order to fab ricate nanocomposite films.Horseradish peroxidase(HRP) has been immobilized onto this chitosan NiFe_2O_4 nanocomposite f...Nickel ferrite(NiFe_2O_4) nanoparticles have been dispersed in chitosan solution in order to fab ricate nanocomposite films.Horseradish peroxidase(HRP) has been immobilized onto this chitosan NiFe_2O_4 nanocomposite film via physical adsorption.The size of the NiFe_2O_4 nanoparticles has been estimated us ing X ray diffraction pattern and scanning electron microscopy(SEM) to be 40±9 nm.The chitosan NiFe_2O_4 nanocomposite film and HRP/chitosan NiFe_2O_4 bioelectrode have been characterized using SEM technique.The HRP/chitosan NiFe_2O_4 nanocomposite bioelectrode has a response time of 4 s,linearity as 0.3 to 12 m M of H2O2,sensitivity as 22 n A/m M.The effects of p H and the temperature of the immobilized HRP electrode have also been studied.展开更多
In the present study, chitosan and polyvinyl alcohol(PVA) were blended with different concentrations of sodium montmorillonite(Na^+MMT) clay solution by a solvent casting method. X-ray diffraction and transition elect...In the present study, chitosan and polyvinyl alcohol(PVA) were blended with different concentrations of sodium montmorillonite(Na^+MMT) clay solution by a solvent casting method. X-ray diffraction and transition electron microscope results show that the film properties are related to the co-existence of Na^+MMT intercalation/exfoliation in the blend and the interaction between chitosan–PVA and Na^+MMT. 5-Fluorouracil(5-FU) was loaded with chitosan–PVA/Na^+MMT nanocomposite films for in vitro drug delivery study. The antimicrobial activity of the chitosan–PVA/Na^+MMT films showed significant effect against Salmonella(Gram-negative) and Staphylococcus aureus(Gram-positive), whereas5-FU encapsulated chitosan–PVA/Na^+MMT bio-nanocomposite films did not show any inhibition against bacteria. Our results indicate that combination of a flexible and soft polymeric material with high drug loading ability of a hard inorganic porous material can produce improved control over degradation and drug release. It will be an economically viable method for preparation of advanced drug delivery vehicles and biodegradable implants or scaffolds.展开更多
Chitosan is a natural biopolymer, derived from chitin, which is used for wood modification. Polyethylene glycol（PEG） was reacted with wood to provide possible fixation of the chitosan to wood. Wood blocks were treat...Chitosan is a natural biopolymer, derived from chitin, which is used for wood modification. Polyethylene glycol（PEG） was reacted with wood to provide possible fixation of the chitosan to wood. Wood blocks were treated with chitosan and PEG, as well as pre-treatment with the PEG at different temperatures and further reaction with the chitosan. The samples were soaked in water to study leaching of the chemicals, water absorption, swelling, as well as anti-swelling efficiency. Any prior reaction of the wood with PEG provided better reaction to the chitosan.Bulking was increased after the treatment of the wood with PEG. Swelling was reduced in the PEG-treated wood blocks as well as the pre-treated samples. Chitosan was not able to protect wood against water penetration： the treated samples showed more water absorption and swelling.However, pre-treatment of the samples decreased swelling in the wood, and the density was not noticeably affected by the treatments. Heating during the treatment caused more reduction in swelling for PEG–chitosan treated samples.展开更多
In this paper, pod-like supramicelles with multicompartment hydrophobic cores were prepared by selfassembly of amphiphilic N-phthaloylchitosan-g-poly(N-vinylcaprolactam)(PHCS-g-PNVCL) in aqueous medium. The employed b...In this paper, pod-like supramicelles with multicompartment hydrophobic cores were prepared by selfassembly of amphiphilic N-phthaloylchitosan-g-poly(N-vinylcaprolactam)(PHCS-g-PNVCL) in aqueous medium. The employed biocompatible amphiphilic polymer was synthesized by grafting the carboxyl terminated poly(N-vinylcaprolactam)(PNVCL-COOH) chains onto N-phthaloylchitosan(PHCS) backbone.~1H NMR and FTIR results confirmed the molecular structure of the copolymers. The morphology of the supramicelles assembled by PHCS-g-PNVCL was revealed by means of TEM and polarized light microscope. In solution, the supramicelles were very stable as monitored by DLS and zeta potential measurements. Temperature and p H presented significant influences on the size and size distribution of the supramicelles. These supramicelles with multicompartment hydrophobic cores should be ideal biomimetic systems with promising applications in drug delivery.展开更多
Adult New Zealand white rabbits were used in this study. The knee joint of rabbits was experimentally traumatized. 2% solution of chitosan was applied in the experimental group (group A). The rabbits of the control gr...Adult New Zealand white rabbits were used in this study. The knee joint of rabbits was experimentally traumatized. 2% solution of chitosan was applied in the experimental group (group A). The rabbits of the control group (group B) were not treated with chitosan. The hind limb of the rabbits was immobilized with plaster cast from toe to groin. After 3 or 6 weeks,the animals were killed and the specimens were observed. The results showed that the degree of angular movement of the knee joint in group A was greater than that of group B (P<0.01). Adhesion in group B was more severe than that in group A (P<0. 01). Histological studies indicated slight synovium,little connective tissue in suprapatellar sac and collagenous fiber in matrix,and normal shape and size of the synovial cell in group A. The results of this study suggest that chitosan can prevent or alleviate post-traumatic adhesion of joint.展开更多
In the process of exploration and development of oil and gas fields, the acidic environment of oil reservoir, production and transport processes cause corrosion of pipelines and equipment, resulting in huge economic l...In the process of exploration and development of oil and gas fields, the acidic environment of oil reservoir, production and transport processes cause corrosion of pipelines and equipment, resulting in huge economic losses and production safety risks. Corrosion inhibitors were widely used in oil industry because of simple operation process and economical. In this study, three environmentally friendly corrosion inhibitors were synthesized based on the natural polysaccharide chitosan. Corrosion inhibition of three dendritic chitosan derivatives (We name them BH, CH and DH) on mild steel in 1 mol/L HCl solution with natural ventilation system was evaluated by weight loss experiment, electrochemical analysis and surface morphology characterization. The experimental results showed that when the three dendritic chitosan derivatives added in the corrosive medium were 500 mg L^(−1), the corrosion inhibition efficiencies were all more than 80%. Based on quantum chemical calculation, inhibition mechanisms of three dendritic chitosan derivatives were investigated according to molecular structures. The results showed that the benzene ring, Schiff base and N atom contained in the molecule were the active centers of electron exchange, which were more likely to form a film on the carbon steel surface, thereby slowing or inhibiting corrosion. The results also predicted the corrosion inhibition effect BH > DH > CH, which was consistent with the experimental conclusion.展开更多
Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environ...Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.展开更多
Chitosan biguanidine hydrochloride(CGH) has been synthesized by the guanidineylation reaction of chitosan with dicyandiamide.The structures of CGH were characterized by Fourier transform infrared spectroscopy and 13CN...Chitosan biguanidine hydrochloride(CGH) has been synthesized by the guanidineylation reaction of chitosan with dicyandiamide.The structures of CGH were characterized by Fourier transform infrared spectroscopy and 13CNMR spectra.In this paper,we used citric acid(CA) as a crosslinking agent,mixed with CGH to perform a pad-drycure treatment on wool fabric to study reaction mechanism during crosslinking with the help of Fourier transform infrared spectroscopy(FT-IR) and scanning electron microscopy(SEM).Dyeing characteristics of CGH treated wool fabric was assessed.The effects of CGH concentration,curing temperature,dipping time,pH value on color yield of reactive dyes on wool fibres were investigated.Fastness properties of the modified wool fabric to laundering and crocking have also been discussed.Fourier transform infrared spectroscopy(FT-IR) showed that CA produce esterification with the-OH group of the wool and transamidation with the-NH2 group of the CGH to form a crosslink.Scanning electron microscopy(SEM) analysis showed the CGH firmly attached to the surface of wool fibre.It was found that the CGH pretreated wool fabrics had significantly improved dyeability characteristics.It is worthwhile to mention that the CGH treated samples have antibacterial potential due to the antibacterial property of chitosan molecules and guanidinium salts.展开更多
The ability to replicate the microenvironment of the human body through the fabrication of scaffolds is a significant achievement in the biomedical field.However,the search for the ideal scaffold is still in its infan...The ability to replicate the microenvironment of the human body through the fabrication of scaffolds is a significant achievement in the biomedical field.However,the search for the ideal scaffold is still in its infancy and there are significant challenges to overcome.In the modern era,the scientific community is increasingly turned to natural substances due to their superior biological ability,lower cost,biodegradability,and lower toxicity than synthetic lab-made products.Chitosan is a well-known polysaccharide that has recently garnered a high amount of attention for its biological activities,especially in 3D bone tissue engineering.Chitosan closely matches the native tissues and thus stands out as a popular candidate for bioprinting.This review focuses on the potential of chitosan-based scaffolds for advancements and the drawbacks in bone treatment.Chitosan-based nanocomposites have exhibited strong mechanical strength,water-trapping ability,cellular interaction,and biodegradability.Chitosan derivatives have also encouraged and provided different routes for treatment and enhanced biological activities.3D tailored bioprinting has opened new doors for designing and manufacturing scaffolds with biological,mechanical,and topographical properties.展开更多
Aqueous zinc-ion batteries encounter enormous challenges such as Zn dendrites and parasitic reactions.Separator modification is a highly effective strategy to address these issues.With the advantages of low cost,nonto...Aqueous zinc-ion batteries encounter enormous challenges such as Zn dendrites and parasitic reactions.Separator modification is a highly effective strategy to address these issues.With the advantages of low cost,nontoxicity,biodegradability,good film-forming ability,superior hydro phi licity,and rich functional groups,chitosan is an ideal matrix for constructing separators.However,the presence of positive charges within chitosan in weakly acidic electrolytes is unfavorable for dendrite inhibition.Herein,Schiff base reaction is introduced to modify chitosan matrix,transforming its charge polarity from positive to negative.Additionally,NbN with excellent zincophilicity is coated onto chitosan matrix,forming a Janus separator with low thickness of 19μm and considerably improved mechanical properties.The resultant separator can promote the transport of Zn^(2+)ions while triggering a repulsive shielding effect against anions,therefore dramatically enhancing Zn^(2+)ion transfer number from 0.28 to 0.49.This separator can also facilitate desolvation process,improve exchange current density,restrict two-dimensional Zn^(2+)ion diffusion,and enhance electrochemical kinetics,contributing to significantly inhibited dendrite growth,by-product formation,and hydrogen evolution.Consequently,stable and reversible Zn stripping/plating process is enabled for over 2500 h at 2 mA cm^(-2)and 2 mAh cm^(-2).And great rate capability and excellent cyclability can be achieved for full batteries even under harsh conditions.This work provides new insights into separator design for Zn-based batteries.展开更多
基金supported by the National Nature Science Foundation of China (No.50776020 and No. 50836005)
文摘The kinetic inhibiting effect of a number of chitosans on hydrate formation was investigated using methane and methane/ethane gas mixtures.The results indicated that chitosan was a good kinetic inhibitor.The induction time of gas hydrate formation evidently increased with the degree of deacetylation （DD）,however,when DD was higher than 80%,the effect of DD on the induction time was negligible.Moreover,it was found that the molecular weight （MW） of chitosan and the addition of polyethylene oxide （PEO） had little effect on the induction time.The optimal concentration of chitosan was found to be 0.6 wt%.Finally,the mechanisms of the kinetic inhibitor on the hydrate formation were discussed.
基金supported by the National Natural Science Foundation of China(No.81701838)the China Postdoctoral Science Foundation(2018M632628)
文摘Background:LL-37 peptide is a member of the human cathelicidin family,and has been shown to promote the healing of pressure ulcers.However,the low stability of this peptide within the wound environment limits its clinical use.Chitosan(CS)hydrogel is commonly used as a base material for wound dressing material.Methods:CS hydrogel(2.5%w/v)was encapsulated with LL-37.Cytotoxicity of the product was examined in cultured NIH3 T3 fibroblasts.Effects on immune response was examined by measuring tumor necrosis factor-α(TNF-α)release from RAW 264.7 macrophages upon exposure to lipopolysaccharides.Antibacterial activity was assessed using Staphylococcus aureus.Potential effect on pressure ulcers was examined using a mouse model.Briefly,adult male C57 BL/6 mice were subjected to skin pressure using magnets under a 12/12 h schedule for 21 days.Mice were randomized to receive naked LL-37(20μg),chitosan gel containing 20μg LL-37(LL-37/CS hydrogel)or hydrogel alone under the ulcer bed(n=6).A group of mice receiving no intervention was also included as a control.Results:LL-37/CS hydrogel did not affect NIH3 T3 cell viability.At a concentration of 1–5μg/ml,LL-37/CS inhibited TNF-αrelease from macrophage.At 5μg/ml,LL-37/CS inhibited the growth of Staphylococcus aureus.The area of the pressure ulcers was significantly lower in mice receiving LL-37/CS hydrogel in comparison to all other 3 groups on days 11(84.24%±0.25%),13(56.22%±3.91%)and 15(48.12%±0.28%).Histological examination on days 15 and 21 showed increased epithelial thickness and density of newly-formed capillary with naked LL-37 and more so with LL-37/CS.The expression of key macromolecules in the process of angiogenesis(i.e.,hypoxia inducible factor-1α(HIF-1α)and vascular endothelial growth factor-A(VEGF-A))in wound tissue was increased at both the mRNA and protein levels.Conclusion:Chitosan hydrogel encapsulated with LL-37 is biocompatible and could promote the healing of pressure ulcers.
基金supported by National Basic Research Program of China （No. 2012CB619100）, National High Technology Research and Development Program of China （No. 2011AA030105）
文摘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.
基金financially supported by the Science and Technology Program of Guangzhou(202002030307)the Natural Science Foundation of Guangdong Province(2019A1515010595 and 2019A1515111030)+1 种基金the International Cooperative Research Program of Shenzhen(GJHZ20180411143536149)Guangdong Provincial Key Laboratory of Energy Materials for Electric Power(2018B030322001)。
文摘Poor cycling performance caused by the shuttle effect of polysulfides is the main obstacle in the development of advanced lithium-sulfur(Li-S)batteries.Functional polymer binders with polar groups can effectively adsorb polysulfides chemically,thereby suppressing the shuttle effect.Herein,a robust three-dimensional crosslinked polymer network,which demonstrates excellent mechanical property and strong affinity for polysulfides,is prepared by the aldimine condensation and coordination reactions.The crosslinked chitosan sulfate network(CCSN)significantly enhances the cycling performance and rate capability of the sulfur cathode.The CCSN-based sulfur cathode exhibits a high initial discharge capacity of 824 m Ah g^(-1) with only 0.082%average capacity loss per cycle at 1 C.At a high rate of 4 C,the cathode exhibits a high capacity retention of 84.8%after 300 cycles.Moreover,the CCSN-based sulfur cathode exhibits an excellent cycling performance at a high sulfur loading of 2.5 mg cm^(-2),which indicates the excellent mechanical strength and binding performance of the CCSN binder for high-energy density Li-S batteries.This study demonstrates a viable approach for developing high-performance Li-S batteries for practical application.
基金supported by the National Natural Science Foundation of China (No. 30972055, 31101286)Agricultural Science and Technology Achievements Transformation Fund Projects of the Ministry of Science and Technology of China (No.2011GB2C60020)
文摘In this paper, a novel and sensitive electrochemical aptasensor for detecting tetracycline(TET)with prussian blue(PB) as the label-free signal was fabricated. A PB-chitosan-glutaraldehyde(PB-CS-GA)system acting as the signal indicator was developed to improve the sensitivity of the electrochemical aptasensor.Firstly, the PB-CS-GA was fixed onto the glass carbon electrode surface. Then, colloidal gold nanoparticles(Au NPs) were droped onto the electrode to immobilize the anti-TET aptamer for preparation of the aptasensor.The stepwise assembly process of the aptasensor was characterized by cyclic voltammetry(C-V) and scanning electron microscope(SEM). The target TET captured onto the electrode induced the current response of the electrode due to the non-conducting biomoleculars. Under the optimum operating conditions, the response of differential pulse voltammetry(DPV) was used for detecting the concentration of TET. The proposed aptasensor showed a high sensitivity and a wide linear range of 109-～ 105-M and 105-～ 102-M with the correlation coefficients of 0.994 and 0.992, respectively. The detection limit was 3.2×1010-M(RSD 4.12%). Due to its rapidity, sensitivity and low cost, the proposed aptasensor could be used as a pre-scanning method in TET determination for the analysis of livestock products.
基金funded by the National Key Research and Development Project (No. 2020YFC1807700)the National Key Research and Development Project (No. 2019YFC1805900)+4 种基金the Youth Fund Project of GRINM (No. 12008)the Youth Fund Project of GRINM (No. 12119)the Open Foundation of State Key Laboratory of Mineral Processing (No. BGRIMM-KJSKL-2020-07)the Open Foundation of State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization (No. 2021P4FZG13A)the National Natural Science Foundation of China (No. 51704028)。
文摘A novel porous nanocomposite,cross-linked chitosan and polyethylene glycol(PEG) bead-supported MnFe_(2) O_(4) nanoparticles(CPM),was developed as an efficient adsorbent to remove metalloid(As(Ⅲ))and heavy metals(Cd(Ⅱ),Cu(Ⅱ),and Pb(Ⅱ)).The characteristics of CPM showed a porous structure,well dispersed MnFe_(2) O_(4),and several of hydroxyl and amino groups(-OH,-NH_(2)).Batch experiments demonstrated that the best adsorption property of As(Ⅲ),Cd(Ⅱ),Cu(Ⅱ),and Pb(Ⅱ) was achieved within 8 h with maximum adsorption capacities of 9.90,9.73,43.94,and 11.98 mg/g,respectively.Competitive and synergistic effects(particularly precipitation) were included in the co-adsorption mechanism of As(Ⅲ) and heavy metals.Thereinto,As(Ⅲ) was partly oxidized by MnFe_(2) O_(4) to As(V),and both were coordinated on MnFe_(2) O_(4) nanoparticles.Pb(Ⅱ) could also bind to MnFe_(2) O_(4) by ion exchange and electrostatic attraction.Furthermore,Cd(Ⅱ) and Cu(Ⅱ) tended to be coordinated on chitosan.Therefore,CPM can serve as a remediation material for water and soil co-contaminated with As(Ⅲ) and heavy metals.
基金supported by National Natural Science Foundation of China(No.40901150)
文摘Pulsed discharge plasma has exhibited active potential to prepare low molecular weight chitosan. In the present study, the viscosity of ehitosan solution was decreased noticeably after treated with pulsed corona discharge plasma. An experimental investigation on electrical characteristics of pulsed corona discharge plasma in chitosan solution was conducted with a view toward getting insight into discharge process. Factors affecting I-V curve, single pulse injec- tion energy and pulse width were studied. Experimental results showed positive effect of pulsed peak voltage on discharge plasma in chitosan solution. Pulse-forming capacitor greatly influenced the discharge form, and 4 nF was observed as a suitable value for efficiently generating stable discharge plasmas. As the electrode distance was larger than 10 ram, it had slight impact on dis- charge plasma due to the excellent conductive-property of chitosan solution. The injection energy significantly increased with air flow rate, while the pulse width hardly changed as the air flow rate increased from 0.5 m^3/h to 1.0 m^3/h. This study is expected to provide reference for promoting the application of pulsed corona discharge plasma to ehitosan solution treatment.
文摘Recently, chitosan nanoparticles have been an attractive biomaterial for their unique properties. Chitosan nanoparticles are mainly used as drug delivers. However, they are seldom used in wound healing after severe bleeding. In the present paper, chitosan nanoparticles with an average size of 60.2 nm were prepared through ionic gelation and characterized by X-ray diffraction and FT-infrared spectrometry. A new animal model of severe bleeding was made to evaluate its effects on wound healing besides hemostasis. The results showed that it can achieve well hemostatic effects and also induce wound healing after severe bleeding. Blood cells can be absorbed by chitosan nanoparticles and the bleeding is treated. Furthermore, the chitosan nanoparticles sustains longer than other materials in wound healing. At the 15th day after operation, the chitosan nanoparticles with the size of 58.3 nm can still be seen in the new-regenerated hepatic tissue. It can induce the formation of a clear granulation around the wound site. Through histological observation, we find out that chitosan-TPP nanoparticles can induce wound healing through migration of the inflammatory cells and synthesis of collagen. So, chitosan nanoparticles show us both hemostasis and the ability of wound healing for parenchymal organs.
基金the Fatih University,Research Project Foundation (Contract no:P500209022)Scientific and Technological Research Council of Turkey (TBTAK) (Pro ject no:110T487)TURKEY Prime Ministry State Planning Organization
文摘Nickel ferrite(NiFe_2O_4) nanoparticles have been dispersed in chitosan solution in order to fab ricate nanocomposite films.Horseradish peroxidase(HRP) has been immobilized onto this chitosan NiFe_2O_4 nanocomposite film via physical adsorption.The size of the NiFe_2O_4 nanoparticles has been estimated us ing X ray diffraction pattern and scanning electron microscopy(SEM) to be 40±9 nm.The chitosan NiFe_2O_4 nanocomposite film and HRP/chitosan NiFe_2O_4 bioelectrode have been characterized using SEM technique.The HRP/chitosan NiFe_2O_4 nanocomposite bioelectrode has a response time of 4 s,linearity as 0.3 to 12 m M of H2O2,sensitivity as 22 n A/m M.The effects of p H and the temperature of the immobilized HRP electrode have also been studied.
基金the Tshwane University of Technology for their financial support
文摘In the present study, chitosan and polyvinyl alcohol(PVA) were blended with different concentrations of sodium montmorillonite(Na^+MMT) clay solution by a solvent casting method. X-ray diffraction and transition electron microscope results show that the film properties are related to the co-existence of Na^+MMT intercalation/exfoliation in the blend and the interaction between chitosan–PVA and Na^+MMT. 5-Fluorouracil(5-FU) was loaded with chitosan–PVA/Na^+MMT nanocomposite films for in vitro drug delivery study. The antimicrobial activity of the chitosan–PVA/Na^+MMT films showed significant effect against Salmonella(Gram-negative) and Staphylococcus aureus(Gram-positive), whereas5-FU encapsulated chitosan–PVA/Na^+MMT bio-nanocomposite films did not show any inhibition against bacteria. Our results indicate that combination of a flexible and soft polymeric material with high drug loading ability of a hard inorganic porous material can produce improved control over degradation and drug release. It will be an economically viable method for preparation of advanced drug delivery vehicles and biodegradable implants or scaffolds.
文摘Chitosan is a natural biopolymer, derived from chitin, which is used for wood modification. Polyethylene glycol（PEG） was reacted with wood to provide possible fixation of the chitosan to wood. Wood blocks were treated with chitosan and PEG, as well as pre-treatment with the PEG at different temperatures and further reaction with the chitosan. The samples were soaked in water to study leaching of the chemicals, water absorption, swelling, as well as anti-swelling efficiency. Any prior reaction of the wood with PEG provided better reaction to the chitosan.Bulking was increased after the treatment of the wood with PEG. Swelling was reduced in the PEG-treated wood blocks as well as the pre-treated samples. Chitosan was not able to protect wood against water penetration： the treated samples showed more water absorption and swelling.However, pre-treatment of the samples decreased swelling in the wood, and the density was not noticeably affected by the treatments. Heating during the treatment caused more reduction in swelling for PEG–chitosan treated samples.
基金NSFC Grants(5140306251273063 and 20774030)+4 种基金China Postdoctoral Science Foundation(2013M541485)111 Project Grant(B08021)the Fundamental Research Funds for the Central Universitiesthe higher school specialized research fund for the doctoral program(20110074110003)the Open Project of Engineering Research Center of Materials-Oriented Chemical Engineering of Xinjiang Bingtuan(2015BTRC001)for support of this work
文摘In this paper, pod-like supramicelles with multicompartment hydrophobic cores were prepared by selfassembly of amphiphilic N-phthaloylchitosan-g-poly(N-vinylcaprolactam)(PHCS-g-PNVCL) in aqueous medium. The employed biocompatible amphiphilic polymer was synthesized by grafting the carboxyl terminated poly(N-vinylcaprolactam)(PNVCL-COOH) chains onto N-phthaloylchitosan(PHCS) backbone.~1H NMR and FTIR results confirmed the molecular structure of the copolymers. The morphology of the supramicelles assembled by PHCS-g-PNVCL was revealed by means of TEM and polarized light microscope. In solution, the supramicelles were very stable as monitored by DLS and zeta potential measurements. Temperature and p H presented significant influences on the size and size distribution of the supramicelles. These supramicelles with multicompartment hydrophobic cores should be ideal biomimetic systems with promising applications in drug delivery.
文摘Adult New Zealand white rabbits were used in this study. The knee joint of rabbits was experimentally traumatized. 2% solution of chitosan was applied in the experimental group (group A). The rabbits of the control group (group B) were not treated with chitosan. The hind limb of the rabbits was immobilized with plaster cast from toe to groin. After 3 or 6 weeks,the animals were killed and the specimens were observed. The results showed that the degree of angular movement of the knee joint in group A was greater than that of group B (P<0.01). Adhesion in group B was more severe than that in group A (P<0. 01). Histological studies indicated slight synovium,little connective tissue in suprapatellar sac and collagenous fiber in matrix,and normal shape and size of the synovial cell in group A. The results of this study suggest that chitosan can prevent or alleviate post-traumatic adhesion of joint.
文摘In the process of exploration and development of oil and gas fields, the acidic environment of oil reservoir, production and transport processes cause corrosion of pipelines and equipment, resulting in huge economic losses and production safety risks. Corrosion inhibitors were widely used in oil industry because of simple operation process and economical. In this study, three environmentally friendly corrosion inhibitors were synthesized based on the natural polysaccharide chitosan. Corrosion inhibition of three dendritic chitosan derivatives (We name them BH, CH and DH) on mild steel in 1 mol/L HCl solution with natural ventilation system was evaluated by weight loss experiment, electrochemical analysis and surface morphology characterization. The experimental results showed that when the three dendritic chitosan derivatives added in the corrosive medium were 500 mg L^(−1), the corrosion inhibition efficiencies were all more than 80%. Based on quantum chemical calculation, inhibition mechanisms of three dendritic chitosan derivatives were investigated according to molecular structures. The results showed that the benzene ring, Schiff base and N atom contained in the molecule were the active centers of electron exchange, which were more likely to form a film on the carbon steel surface, thereby slowing or inhibiting corrosion. The results also predicted the corrosion inhibition effect BH > DH > CH, which was consistent with the experimental conclusion.
文摘Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.
文摘Chitosan biguanidine hydrochloride(CGH) has been synthesized by the guanidineylation reaction of chitosan with dicyandiamide.The structures of CGH were characterized by Fourier transform infrared spectroscopy and 13CNMR spectra.In this paper,we used citric acid(CA) as a crosslinking agent,mixed with CGH to perform a pad-drycure treatment on wool fabric to study reaction mechanism during crosslinking with the help of Fourier transform infrared spectroscopy(FT-IR) and scanning electron microscopy(SEM).Dyeing characteristics of CGH treated wool fabric was assessed.The effects of CGH concentration,curing temperature,dipping time,pH value on color yield of reactive dyes on wool fibres were investigated.Fastness properties of the modified wool fabric to laundering and crocking have also been discussed.Fourier transform infrared spectroscopy(FT-IR) showed that CA produce esterification with the-OH group of the wool and transamidation with the-NH2 group of the CGH to form a crosslink.Scanning electron microscopy(SEM) analysis showed the CGH firmly attached to the surface of wool fibre.It was found that the CGH pretreated wool fabrics had significantly improved dyeability characteristics.It is worthwhile to mention that the CGH treated samples have antibacterial potential due to the antibacterial property of chitosan molecules and guanidinium salts.
文摘The ability to replicate the microenvironment of the human body through the fabrication of scaffolds is a significant achievement in the biomedical field.However,the search for the ideal scaffold is still in its infancy and there are significant challenges to overcome.In the modern era,the scientific community is increasingly turned to natural substances due to their superior biological ability,lower cost,biodegradability,and lower toxicity than synthetic lab-made products.Chitosan is a well-known polysaccharide that has recently garnered a high amount of attention for its biological activities,especially in 3D bone tissue engineering.Chitosan closely matches the native tissues and thus stands out as a popular candidate for bioprinting.This review focuses on the potential of chitosan-based scaffolds for advancements and the drawbacks in bone treatment.Chitosan-based nanocomposites have exhibited strong mechanical strength,water-trapping ability,cellular interaction,and biodegradability.Chitosan derivatives have also encouraged and provided different routes for treatment and enhanced biological activities.3D tailored bioprinting has opened new doors for designing and manufacturing scaffolds with biological,mechanical,and topographical properties.
基金the financial support from the Natural Science Foundation of Jiangsu Province(BK20231292)the Jiangsu Agricultural Science and Technology Innovation Fund(CX(24)3091)+2 种基金the National Natural Science Foundation of China(12464032)the Natural Science Foundation of Jiangxi Province(20232BAB201032)supported by the high performance computing university-level public platform of Jinggangshan University.
文摘Aqueous zinc-ion batteries encounter enormous challenges such as Zn dendrites and parasitic reactions.Separator modification is a highly effective strategy to address these issues.With the advantages of low cost,nontoxicity,biodegradability,good film-forming ability,superior hydro phi licity,and rich functional groups,chitosan is an ideal matrix for constructing separators.However,the presence of positive charges within chitosan in weakly acidic electrolytes is unfavorable for dendrite inhibition.Herein,Schiff base reaction is introduced to modify chitosan matrix,transforming its charge polarity from positive to negative.Additionally,NbN with excellent zincophilicity is coated onto chitosan matrix,forming a Janus separator with low thickness of 19μm and considerably improved mechanical properties.The resultant separator can promote the transport of Zn^(2+)ions while triggering a repulsive shielding effect against anions,therefore dramatically enhancing Zn^(2+)ion transfer number from 0.28 to 0.49.This separator can also facilitate desolvation process,improve exchange current density,restrict two-dimensional Zn^(2+)ion diffusion,and enhance electrochemical kinetics,contributing to significantly inhibited dendrite growth,by-product formation,and hydrogen evolution.Consequently,stable and reversible Zn stripping/plating process is enabled for over 2500 h at 2 mA cm^(-2)and 2 mAh cm^(-2).And great rate capability and excellent cyclability can be achieved for full batteries even under harsh conditions.This work provides new insights into separator design for Zn-based batteries.
