In vitro biocompatibility of electrospun hexanoyl chitosan fibrous scaffolds towards human keratinocytes and fibroblasts

With the ability to form a submicron-sized fibrous structure with interconnected pores mimicking the extracellular matrix (ECM) for tissue formation, electrospinning was used to fabricate ultra-fine fiber mats of hexanoyl chitosan (H-chitosan) for potential use as skin tissue scaffolds. In the present communication, the in vitro biocompatibility of the electrospun fiber mats was evaluated. Indirect cytotoxicity evaluation of the fiber mats with mouse fibroblasts (L929) revealed that the materials were non-toxic and did not release substances harmful to living cells. The potential for use of the fiber mats as skin tissue scaffolds was further assessed in terms of the attachment and the proliferation of human keratinocytes (HaCaT) and human foreskin fibroblasts (HFF) that were seeded or cultured on the scaffolds at different times. The results showed that the electrospun fibrous scaffolds could support the attachment and the proliferation of both types of cells, especially for HaCaT. In addition, the cells cultured on the fibrous scaffolds exhibited normal cell shapes and integrated well with surrounding fibers. The obtained results confirmed the potential for use of the electrospun H-chitosan fiber mats as scaffolds for skin tissue engineering.     

玉米醇溶蛋白/壳聚糖复合纳米微球的制备及性能研究

以生物相容性的玉米醇溶蛋白(Zein)和壳聚糖(Chitosan)为原料,利用溶剂-非溶剂相分离法成功制备了玉米醇溶蛋白/壳聚糖复合纳米微球(NSZ/CS),运用FT-IR、SEM和TEM等对复合纳米微球进行了表征。采用罗丹明B(RB)为模型药物分子,研究了复合纳米微球的药物释放性能。与玉米醇溶蛋白纳米微球(NSZ)相比,复合纳米微球NSZ/CS对RB和Dox·HCl的包封率显著上升,分别可达83.5%和75.3%。NSZ/CS对RB的累积释放量也大幅度提高。在模拟人工胃液和人工肠液中,NSZ/CS对RB释放36 h后,累积释放量分别为85.2%和95.4%。进一步将NSZ/CS用于负载抗癌药物盐酸阿霉素(Dox·HCl),发现Dox@NSZ/CS在p H=7.4的磷酸缓冲液(PBS)中的累积释放量达91.0%。复合纳米微球NSZ/CS有望作为水溶性药物载体应用于生物医药领域。     

In vitro biocompatibility of electrospun and solvent-cast chitosan substrata towards Schwann, osteoblast, keratinocyte and fibroblast cells

Chitosan or poly(N-acetyl-d-glucosamine-co-d-glucosamine) with a degree of deacetylation of about 85% was fabricated into nanofibrous membranes by electrospinning from 7% w/v chitosan solution in 70:30 v/v trifluoroacetic acid/dichloromethane solvent system. The obtained fibers were smooth without the presence of beads. The diameters of the individual fiber segments were 126 ± 20 nm. The potential for use of the electrospun chitosan nanofibrous membranes as substrates for cell/tissue culture was evaluated with four different cell types, i.e., Schwann cells, osteoblast-like cells, keratinocytes and fibroblasts, in terms of the attachment and the proliferation of the cells as well as the morphology of the seeded and the cultured cells. The results were compared with the corresponding solvent-cast films. Both types of the chitosan substrates supported the attachment and, at the same time, promoted the largest increase in the viability of the cultured keratinocytes. The viability of Schwann cells cultured on these substrates increased marginally well, but the attachment of the cells on the surfaces was relatively poor. Finally, both types of the chitosan substrates showed cytostatic property towards both osteoblast-like cells and fibroblasts, despite the convincingly good attachment of osteoblast-like cells on the surfaces.     

Preparation and biodegradation of electrospun PLLA/keratin nonwoven fibrous membrane

As a kind of natural protein, wool keratin was used to improve the cell affinity of poly(l-lactic acid) (PLLA). After small keratin particles were prepared from keratin solution by spray-drying process, they were blended with PLLA solution. PLLA/keratin nonwoven fibrous membrane was produced by electrospinning the blend solutions. The release rate of keratin from the composite membrane was detected by Fourier transform infrared (FTIR) after PLLA/keratin membranes were degraded in PBS up to 4 weeks. The chemical compositions of the PLLA/keratin surface were examined by X-ray photoelectron spectroscope. Although more than half of the keratin was removed from PLLA/keratin membrane during the first few hours of degradation, some keratin particles were still embedded in the PLLA fibers. Osteoblast cells were used to evaluate the cellular behaviors of the composite membrane. After 7 days culturing, more cells were observed on PLLA/keratin membranes than on pure PLLA membranes. MTT assay and alkaline phosphatase (ALP) activity results suggested that keratin could improve the interactions between osteoblast cells and the polymeric membranes.     

Electrospinning and characterization of poly(vinyl alcohol)/chitosan oligosaccharide/clay nanocomposite nanofibers in aqueous solutions

Submicron fibers of the composite of poly(vinyl alcohol) (PVA), chitosan oligosaccharide [COS, (1→4)2-amino-2-deoxy-β-d-glucose], and montmorillonite clay (MMT) were prepared using electrospinning method with aqueous solutions. Scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), thermal gravimetric analyzer, and tensile strength testing machine (Zwick) were utilized to characterize the PVA/COS/MMT nanofiber mats morphology and properties. The PVA/COS ratio and MMT concentration play important roles in nanofiber mat properties. XRD and TEM data demonstrated that exfoliated MMT layers were well-distributed within nanofiber. It was also found that the mechanical property and thermal stability were increased with COS and MMT contents.     

胶原蛋白静电纺丝纳米纤维研究进展

由于胶原蛋白静电纺丝纳米纤维具有胶原蛋白的生物活性以及纳米结构材料的优异性能,其在生物医学领域的研究和应用开发取得了非常大的进展。本文首先综述了胶原蛋白静电纺丝纳米纤维的研究现状,讨论了胶原蛋白静电纺丝纳米纤维在组织工程、止血及伤口愈合、载药和防粘连等生物医学领域的应用,最后针对胶原蛋白静电纺丝纳米纤维存在的问题及其未来的发展方向进行了展望。     

A nanofibrous composite membrane of PLGA-chitosan/PVA prepared by electrospinning

Tissue engineering scaffolds produced by electrospinning feature a structural similarity to the natural extracellular matrix. In this study, poly(lactide-co-glycolide) (PLGA) and chitosan/poly(vinyl alcohol) (PVA) were simultaneously electrospun from two different syringes and mixed on the rotating drum to prepare the nanofibrous composite membrane. The composite membrane was crosslinked by glutaraldehyde vapor to maintain its mechanical properties and fiber morphology in wet stage. Morphology, shrinkage, absorption in phosphate buffered solution (PBS) and mechanical properties of the electrospun membranes were characterized. Fibroblast viability on electrospun membranes was discussed by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay and cell morphology after 7 days of culture. Results indicated that the PBS absorption of the composite membranes, no matter crosslinked or not, was higher than the electrospun PLGA membrane due to the introduction of hydrophilic components, chitosan and PVA. After crosslinking, the composite membrane had a little shrinkage after incubating in PBS. The crosslinked composite membrane also showed moderate tensile properties. Cell culture suggested that electrospun PLGA-chitosan/PVA membrane tended to promote fibroblast attachment and proliferation. It was assumed that the nanofibrous composite membrane of electrospun PLGA-chitosan/PVA could be potentially used for skin reconstruction.     

Preparation and characterization of stable chitosan nanofibrous membrane for lipase immobilization

Nanofibrous membrane with a fiber diameter of 80-150 nm was fabricated from mixed chitosan/poly(vinyl alcohol) (PVA) solution by an electrospinning process. Field emission scanning electron microscope and transmission electron microscope were used to characterize the morphology of the nanofibrous membrane. It was found that chitosan nanofibrous membrane with stabilized morphology could be prepared through removing most of PVA from the nascent one with 0.5 M NaOH aqueous solution. This treatment also resulted in an obvious decrease in fiber diameter. The stabilized chitosan nanofibrous membrane was explored as support for enzyme immobilization due to the characteristics of excellent biocompatibility, high surface/volume ratio, and large porosity. Lipase from Candida rugosa was immobilized on the nanofibrous membrane using glutaraldehyde (GA) as coupling reagent. The properties of the immobilized lipase were assayed and compared with the free one. Results showed that, the observed lipase loading on this nanofibrous membrane was up to 63.6 mg/g and the activity retention of the immobilized lipase was 49.8% under the optimum condition. The pH and thermal stabilities of lipase were improved after it was immobilized on the chitosan nanofibrous membrane. In addition, the experimental results of reusability and storage stability indicated that the residual activities of the immobilized lipase were 46% after 10 cycles and 56.2% after 30 days, which were obviously higher than that of the free one.     

Molecular Imprinting Fibrous Membranes of Poly（ acrylonitrile-co-acrylic acid） Prepared by Electrospinning

Introduction Overthepastfewdecades,molecularimprinting hasbeendescribedasatechnologyforpreparing“mo leculardoors”whichcanbematchedto“template keys”.Ithasbeenfoundtobeasimpleandeffective approachtointroducespecificrecognitionsitesintosyn theticpolymers…     

Electrospun dextran fibrous membranes

Ultra-fine fiber mats of dextran (powder; M _w = 64,000–76,000 Da) were fabricated by electrospinning, using water as the solvent. The effects of solution concentration (i.e., 0.7–1.3 g mL⁻¹) and applied electric field (9–21 kV/15 cm) on morphological appearance and size of the obtained fibers were investigated. Under a fixed electric field of 15 kV/15 cm and a fixed solution flow rate of 0.25 mL h⁻¹, beaded fibers were observed up to a critical concentration of about 0.9 g mL⁻¹, beyond which only smooth fibers were obtained. The average diameter of these fibers increased monotonically with increasing the solution concentration (i.e., from ∼290 to ∼1950 nm). For the dextran solutions investigated, increasing the electric field generally caused the diameters of the obtained fibers to increase, with the average diameter of the obtained fibers ranging between 520 and 1760 nm. To improve the usefulness of the electrospun dextran fiber mats in an aqueous medium, cross-linking with glutaraldehyde was necessary. The effects of curing temperature (i.e., 70–90 °C), curing time (i.e., 3–48 h), and added MgCl₂ catalyst (i.e., 0.01–0.03 g) on physical integrity of the cross-linked dextran membranes in water were investigated. Both the swelling and the weight loss in water of the cross-linked membranes were generally found to decrease with increasing curing temperature, curing time, and MgCl₂ loading and the cross-linking did not affect the morphology of the obtained membranes.     

Preparation and characterization of crosslinked chitosan-based nanofibers

Crosslinked chitosan-based nanofibers were successfully prepared via electrospinning technique with heat mediated chemical crosslinking followed.The structure,morphology and mechanical property of nanofibers were characterized by attenuated total reflection-Fourier transform infrared spectroscopy(ATR-FTIR),scanning electron microscopy(SEM),Instron machine,respec- tively.The results showed that,nanofibers exhibited a smooth surface and regular morphology,and tensile strength of nanofibers improved with increasing of triethylene glycol dimethacrylate(TEGDMA)content.     

Chitosan/poly(tetrafluoroethylene) composite membranes using in pervaporation dehydration processes

Chitosan/PTFE composite membranes were prepared from casting a γ-(glycidyloxypropyl)trimethoxysilane (GPTMS)-containing chitosan solution on poly(styrene sulfuric acid) grafted expended poly(tetrafluoroethylene) film surface. The adhesion between the chitosan skin layer and the PTFE substrate was pretty good to warrant the high performance of chitosan/PTFE composite membranes using in pervaporation dehydration processes on isopropanol. The chitosan/PTFE membrane exhibited a permeation flux of 1730 g/m² h and a separation factor of 775 at 70 °C on pervaporation dehydration of a 70 wt% isopropanol aqueous solution. The membrane also survived after a long-term operation test in 45 days.     

磷钼酸/聚苯乙烯/聚乙烯醇电纺纤维膜的制备及性能

采用静电纺丝法制备了磷钼酸/聚苯乙烯(PS)/聚乙烯醇(PVA)复合纤维,并将其模压成膜.利用红外光谱(IR)、扫描电子显微镜(SEM)及X射线能谱(EDX)等对复合纤维及其膜的结构与形貌进行表征,并对复合纤维膜的光催化性能、力学性能及在水中稳定性进行测试.结果表明,在复合纤维中磷钼酸的Keggin结构得到保持.PS与PVA质量比为1∶1时,复合纤维形貌最佳,表面光滑,直径较小且分布均匀,复合纤维的直径随着磷钼酸含量的增加而减小.将磷钼酸固载于复合纤维膜上比直接使用具有更高的光催化活性,光照25 min后接近98%的甲基橙降解;复合纤维膜易于回收再利用,5次重复使用后,复合纤维膜没有破损,磷钼酸损失较少,光催化性能无明显下降.复合纤维膜的强度随磷钼酸含量的增加先增大后减小,韧性随PVA含量的增加而增大,随磷钼酸含量的增加而减小.     

A preliminary study on fabrication of nanoscale fibrous chitosan membranes in situ by biospecific degradation

A new approach for in situ fabrication of nanoscale fibrous chitosan membrane by biospecific degradation under physiological situation was studied. The chitosan binary blend membranes were fabricated by solvent casting of chitosan solution containing highly deacetylated chitosan (HDC) and moderately deacetylated chitosan (MDC) with different ratio. The biodegradation process was performed in PBS (pH 7.4) containing lysozyme at the temperature of 37 °C. Experimental results from weight loss, reducing sugar in surrounding media, FT-IR, X-ray diffraction, gel permeation chromatography (GPC) and SEM throughout the study showed that the biospecific degradation by lysozyme had removed MDC component selectively. When the ratio of MDC in the binary blend membranes amounted to 0.5, nanoscale domains of HDC and MDC were obtained, and thus a nanoscale fibrous structure was fabricated after biospecific degradation of MDC. This nanofibrous structure and the biospecific degradation of chitosan membranes can have potential advantages and interesting implications in tissue engineering and drug delivery.     

静电纺丝制备空气过滤用抗分层聚酰胺66/聚丙烯腈/聚醚砜(PA-66/PAN/PES)三明治结构膜

通过在经处理的不锈钢网(SSM)上逐层电纺制备了简易有效的聚酰胺66/聚丙烯腈/聚醚砜(PA-66/PAN/PES)复合纤维过滤材料.材料中间层采用以N,N-二甲基甲酰胺(DMF)为溶剂的PAN/PES共混聚合物电纺而成.扫描电子显微镜表征和比表面积测试结果表明, 在相同纺丝条件下PES量的增加有利于减小纤维直径, 增大膜的孔隙率.同时, 通过拉伸实验测量了未带有SSM的膜的机械性能(5.857 MPa).利用PES的良好疏水性, 过滤膜表面具有相对良好的疏水效果, 接触角约为130.58°.在样品厚度尽可能相等的情况下, 通过对实际空气环境中0.3~5 μm的颗粒进行截流测试发现, PAN/PES-3的过滤效率达到且大于99%.通过机械振动和空气反吹考察了过滤膜的再生性能.此外, 还通过使用喷雾喷涂SSM研究了防分层过滤介质的基质.     

Blended chitosan and polyvinyl alcohol membranes for the pervaporation dehydration of isopropanol

Homogeneous membranes were prepared by casting the solution of blended chitosan and polyvinyl alcohol (PVA) on a glass plate. The percent weight of chitosan in the membrane was varied from 0 to 100%. The membrane thickness was in the range of 15–30 μm. The membranes were heat treated at 150 °C for an hour. After that the membranes were crosslinked by glutaraldehyde and sulfuric acid in acetone aqueous solution. The membranes were tested at 30–60 °C for dehydration performance of 50–95% isopropanol aqueous solutions. At around 90% of isopropanol in the feed mixture, permeate flux increased whereas the percent of water in permeate tended to decrease when the feed temperature increased for all membranes, except that the water content in permeate from the membrane containing 75 wt.% chitosan remained constant. The swelling degree in water and the total flux increased with increasing chitosan content in membranes. The effect of temperature on permeate flux followed the Arrhenius relationship. The permeate flux decreased when isopropanol in the feed increased for all membranes. However, water content in permeate and isopropanol concentration in the feed formed complex relationship for different chitosan content membranes. Sorption did not appear to have significant effects on separation. The membrane containing chitosan 75% performed the best. For a feed solution containing 90% isopropanol at 60 °C, the permeate flux was 644 g/m² h with water content of nearly 100% in the permeate. At 55% isopropanol in the feed at 60 °C, the permeate flux was 3812 g/m² h. In the range of 55–95% of isopropanol in the feed, the water content in permeate was more than 99.5%. This membrane showed very excellent performance with good mechanical strength. It is promising to develop this membrane for industrial uses.     

Using NaCl particles as porogen to prepare a highly adsorbent chitosan membranes

Macroporous chitosan membranes were prepared by using NaCl particles porogen and genipin as cross-linking agent. For characterization and sorption behavior comparison, other genipin cross-linked chitosan membranes were prepared by either freeze drying or by using silica particles as porogen. The mean pore diameter, the porosity, the crystallinity index (CrI) as well as the effect of the drying procedures of these chitosan membranes were examined. NaCl reduced the CrI of the chitosan membrane. The oven drying (OD) procedure decreased the mean pore diameter, the porosity, and increased the CrI of the chitosan membranes when compared with the vacuum drying (VD) procedure. The heat treatment of chitosan membrane in aqueous NaOH to attract silica porogen increased the CrI of the membrane. Under the same conditions, the membranes prepared with NaCl had better sorption performance on RR 189 and Cu²⁺ than other membranes. The maximum sorption capacity (q_e) reached 1836.17 mg RR 189/g chitosan and 151.98 mg Cu²⁺/g chitosan. The pore diameter (d_pore) of the membranes was much larger than the diameter of the adsorbate molecules (d_adsorbate), such that the ratio of d_pore/d_adsorbate had little influence on q_e. The porosity and the amorphous extent of the membranes were almost the same on q_e. When using tyrosinase catalyzing, the hydrocaffeic acid (HCA) grafted on the NaCl treated chitosan membrane was almost 10 times more than on chitosan beads. The chitosan membrane prepared with NaCl can be used as a good adsorbent with high loading capacity for implanting molecules (such as ligands, enzymes, etc.) on.     

A novel composite chitosan membrane for the separation of alcohol-water mixtures

A novel alcohol dehydration membrane with a three layer structure has been prepared. The top layer is a thin dense film of chitosan (CS), and the support layer is made of microporous polyacrylonitrile (PAN). Between the dense and microporous layer, there is an intermolecular cross-linking layer. This novel composite membrane has a high separation factor of more than 8000 and a good permeation rate of 0.26 kg/m² h for the pervaporation of 90 wt% ethanol aqueous solution at 60°C, 0.8 kg/m² h flux for a n-PrOH/water system and around 1 kg/m² h flux for an i-PrOH/water system using 80 wt% alcohol concentration at 60°C. The separation factor for both cases is more than 10⁵. The separation performance varies with feed composition, operating temperature and conditions of membrane preparation. The results show that the separation factor and flux of this membrane increase with raising the operating temperature. At the same time, the crosslinking layer improves durability of the composite membrane, and the pervaporation performance can be adjusted by changing the structure of the cross-linking layer. The cross section of the composite membrane has been examined by SEM.     

Physico-chemical characterisation of chitosan/halloysite composite membranes

Chitosan membranes reinforced by halloysite nanotubes (HNTs) at concentrations from 2 to 15 (w/w%) have been prepared by solution casting to investigate the optimal physico-chemical properties for biomedical applications. Tensile test data revealed that the membranes reinforced with 5 (w/w%) HNTs yielded the highest Young's modulus (0.52 ± 0.01 GPa) and strength (81.6 ± 4.4 MPa). Electron micrographs of the fractured surfaces implicated the interplay between individual HNTs and agglomerates of HNTs in the stress transfer mechanism. Infrared spectra revealed interaction between the HNT siloxane and chitosan functional groups. Thermogravimetric results demonstrated that the thermal stability of the membranes increased with HNT concentration.     

肝素化壳聚糖季铵盐／壳聚糖复合膜抗凝血性能的研究

以壳聚糖季铵盐，壳聚糖为基本原材料，选用戊二醛为交剂剂及固定剂，制备一种物理机械性能较优的抗凝血材料。探讨了戊二醛及肝素钠两者用量对肝素化程度及血液生的影响。