Thin natural gelatin/chitosan nanofibrous scaffolds for retinal pigment epithelium cells

Damage of the retinal pigmented epithelial cells causes various diseases such as age-related macular degeneration in retinal tissue. Nowadays, scientists are attempting to replace lost retinal cells with healthy and efficient cells that provide better conditions for recovering and preventing blindness. In this study, gelatin/chitosan nanofibrous scaffolds with mean diameters of 180?nm were fabricated for subretinal space through electrospinning. Thickness and morphology of the gelatin–chitosan scaffolds were analyzed by scanning electron microscopy (SEM). The results showed that the high rate of degradation, i.e., 90% damage was obtained after 1 month. The cell viability of gelatin/chitosan nanofibers were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The SEM results of cultured RPE on gelatin/chitosan scaffolds showed the appropriate adhesion of cells on the substrate. The results of the identity of RPE cells cultured on the scaffolds indicated that a large number of cells strongly expressed RPE65 and cytokeratin 8/18.     

A study on the fabrication of porous chitosan/gelatin network scaffold for tissue engineering

A novel porous chitosan/gelatin scaffold for tissue engineering was prepared via polyelectrolyte complex formation, freeze drying and post‐crosslinking with glutaraldehyde. The porosity and mean pore diameters could be controlled within 30∼100 µm by varying the original water content and the freezing conditions. Dipping the scaffolds in poly(lactic acid) provided good mechanical properties making it a promising candidate towards tissue engineering. © 2000 Society of Chemical Industry     

Fabrication and DOE Optimization of Electrospun Chitosan/Gelatin/PVA Nanofibers for Skin Tissue Engineering

Chitosan/gelatin-based nanofibers display excellent biological performance in tissue engineering because of their biocompatible composition and nanofibrous structure with a high surface-to-volume ratio mimicking the native extracellular matrix. In this study, to save time and cost of experiments, a response surface methodology based on Box–Behnken design (BBD) is developed to predict the mean diameter of (chitosan:gelatin)/poly(vinyl alcohol) (PVA) nanofibers in three volume ratios of chitosan:gelatin by considering PVA percentage, applied voltage, and flow rate as input variables. The morphology and chemical composition of nanofibers are investigated through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The optimum conditions to yield the minimum diameter of nanofibers with chitosan:gelatin ratios of 25:75, 50:50, and 75:25 are found and result in 165, 121, and 92 nm, respectively, which show good accordance with BBD estimated results. The tensile testing indicates that nanofibers containing higher ratio of chitosan:gelatin result in higher tensile stress and lower toughness and tensile strain. The water contact angle analysis (WCA) shows the appropriate hydrophilicity of crosslinked nanofibers. The MTT assay shows excellent cell viability and cell attachment of nanofibers for mouse fibroblast (L929) cells. The results indicate that optimum nanofibers are potent candidates for wound healing applications.     

Fabrication and characterization of chitosan/gelatin porous scaffolds with predefined internal microstructures

The fabrication process for a novel three-dimensional (3D) chitosan/gelatin scaffold with predefined multilevel internal architectures and highly porous structures is presented combining solid freeform fabrication (SFF), microreplication and lyophilization techniques. The computer model of the scaffold is designed with biological data such as branching angle in liver vascular cast incorporated. Stereolithography (SL), known as a SFF technique, is utilized to build the resin mould, based on which poly-dimethylsilicone (PDMS) mould is produced by microreplication. The chitosan/gelatin hybrid solution is then cast onto the PDMS mould for pre-freeze and the monolayer porous structures with organized internal morphology are produced upon lyophilization. The 3D scaffold can be constructed via stacking these monolayer structures. The properties of porous structure, such as porosity, pore size and micromorphology as well as wall thickness, were investigated. Scanning electron microscopy (SEM) demonstrated that the scaffold possesses multilevel organized internal morphologies including vascular systems (portal vein, artery and hepatic vein) and parenchymal component (hepatocyte chamber). These organized structures enable orderly arrangement of hepatocyte and hepatic nonparenchymal cells and co-culture in the same 3D scaffold to guide liver regeneration in a controlled manner. Cell culture experiment in vitro showed that hepatocytes perform better in the well-defined chitosan/gelatin scaffold than in porous scaffold. This approach makes it flexible to investigate the relationship between internal scaffold microstructure and hepatocyte behavior in vitro. It also provides a new way to fabricate complex 3D scaffold using various natural biomaterials for vital organ engineering.     

壳聚糖/结冷胶双层膜制备工艺优化及表征

以壳聚糖（CS）和结冷胶（GG）为原料,采用溶液流延法并结合层层自组装技术制备了CS/GG双层膜,通过单因素和响应面试验优化制备工艺条件,并对双层膜的微观形貌、化学结构、力学性能、光学性能、阻水性能和抗氧化性能进行评价。结果表明,CS质量分数1.7 %、GG质量分数1.5 %、CS与GG成膜液体积比4/6、甘油质量分数25 %条件下双层膜的拉伸强度为38.83 MPa、透湿量为750.76 g/（m²·d）;与单层膜相比,CS/GG双层膜表面光滑、截面致密,红外光谱分析结果表明双层膜具有良好的相容性;双层膜可以有效改善纯CS膜、纯GG膜的力学性能和阻水性能。     

pH-sensitive chitosan/gelatin hybrid polymer network microspheres for delivery of cimetidine

pH responsive chitosan/gelatin hybrid polymer network (HPN) microspheres were prepared via the inverse emulsion crosslinking method. Cimetidine release from the microspheres was studied. The drug only delivers in acidic medium, while the release rate can be controlled by the HPN composition and the degree of deacetylation.     

Preparation and characterization of porous scaffold composite films by blending chitosan and gelatin solutions for skin tissue engineering

Biodegradable polymers have significant potential in biotechnology and bioengineering. However, for some applications, they are limited by their inferior mechanical properties and unsatisfactory compatibility with cells and tissues. In the present investigation blends of chitosan and gelatin with various compositions were produced as candidate materials for biomedical applications. Fourier transform infrared spectral analysis showed good compatibility between these two biodegradable polymers. The composite films showed improved tensile properties, highly porous structure, antimicrobial activities, low water dissolution, low water uptake and high buffer uptake compared to pure chitosan or gelatin films. These enhanced properties could be explained by the introduction of free ? OH, ? NH₂ and ? NHOCOCH₃ groups of the amorphous chitosan in the blends and a network structure through electrostatic interactions between the ammonium ions (? NH³⁺) of the chitosan and the carboxylate ions (? COO^?) of the gelatin. Scanning electron microscopy images of the blend composite films showed homogeneous and smooth surfaces which indicate good miscibility between gelatin and chitosan. The leafy morphologies of the scaffolds indicate a large and homogeneous porous structure, which would cause increased ion diffusion into the gel that could lead to an increase in stability in aqueous solution, buffer and temperature compared to the gelatin/chitosan system. In vivo testing was done in a Wistar rat (Rattus norvegicus) model and the healing efficiencies of the scaffolds containing various compositions of chitosan were measured. The healing efficiencies in Wistar rat of composites with gelatin to chitosan ratios of 10:3 and 10:4 were compared with that of a commercially available scaffold (Eco‐plast). It was observed that, after 5 days of application, the scaffold with a gelatin to chitosan ratio of 10:3 showed 100% healing in the Wistar rat; however, the commercial Eco‐plast showed only a little above 40% healing of the dissected rat wound. Copyright © 2012 Society of Chemical Industry     

Kinetics of in vitro drug release from chitosan/gelatin hybrid membranes

In vitro studies of controlled release from chitosan/gelatin hybrid membranes were carried out using drugs of different molecular weight. It was found that release of urea, 5-fluorouracil (5-Fu), sodium benzoate, sodium salicylate, sodium mandelate, and sulfacetamide sodium followed zero-order kinetics after a short time lag. Variation of the diffusion coefficient, permeation coefficient, and degree of hydration with crosslinking and varying weight percent of gelatin in membrane matrices were studied in detail by using 5-Fu as a model drug. The diffusion coefficient and permeation coefficient of 5-Fu are dependent on the degree of hydration of the swollen membrane. The transport process of drug molecules in the hydrogel membrane is presumed to be predominantly of the pore mechanism. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1751–1758, 1998     

Fabrication and characterization of chitosan/PVA with hydroxyapatite biocomposite nanoscaffolds

Nanofibrous biocomposite scaffolds of chitosan (CS), PVA, and hydroxyapatite (HA) were prepared by electrospinning. The scaffolds were characterized by FTIR, SEM, TEM, and XRD techniques. Tensile testing was used for the characterization of mechanical properties. Mouse fibroblasts (L929) attachment and proliferation on the nanofibrous scaffold were investigated by MTT assay and SEM observation. FTIR, TEM, and XRD results showed the presence of nanoHA in the scaffolds. The scaffolds have porous nanofibrous morphology with random fibers in the range of 100–700 nm diameters. The CS/PVA (90/10) fibrous matrix (without HA) showed a tensile strength of 3.1 ± 0.2 MPa and a tensile modulus 10 ± 1 MPa with a strain at failure of 21.1 ± 0.6%. Increase the content of HA up to 2% increased the ultimate tensile strength and tensile modulus, but further increase HA up to 5–10% caused the decrease of tensile strength and tensile modulus. The attachment and growth of mouse fibroblast was on the surface of nanofibrous structure, and cells' morphology characteristics and viability were unaffected. A combination of nanofibrous CS/PVA and HA that mimics the nanoscale features of the extra cellular matrix could be promising for application as scaffolds for tissue regeneration, especially in low or nonload bearing areas. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of a novel thermosensitive hydrogel based on chitosan and gelatin blends

In this study, a novel injectable in situ gelling thermosensitive hydrogel system based on chitosan and gelatin blends was designed and investigated. The addition of gelatin provides the correct buffering and other physicochemical conditions including control of hydrophobic interactions and hydrogen bonding, which are necessary to retain chitosan in solution at neutral pH near 4°C and furthermore to allow gel formation upon heating to body temperature. The chitosan/gelatin hydrogels were studied by FTIR, swelling, and rheological analysis. The rheological analysis evidenced the endothermic gelation of chitosan/gelatin solutions, which indicated their gelation temperatures and reflected the effect of gelatin concentration on the thermosensitive properties of gels. The morphology of this system was examined with laser scanning confocal microscopy and scanning electron microscopy. The images indicated that the gels were quite heterogeneous and porous. The investigation of these gels as vehicles for delivering bovine serum albumin as a model drug of protein showed that the system could sustain the release of the protein drug. These results show that chitosan/gelatin solutions can form gels rapidly at body temperature and have promising perspective for their use in local and sustained delivery of protein drug. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fabrication and properties of PLLA‐gelatin nanofibers by electrospinning

Poly(L ‐lactide acid)‐blend‐gelatin (PLLA‐gelatin) nanofibers were successfully fabricated by means of electrospinning. The different material components characterizing the properties of electrospun PLLA/G nanofibers were measured and the effect of PLLA weight ratios on such properties as morphologies, physical and chemical structure and mechanical profiles were analyzed. It was found that the fibers diameter increases and the ultimate tension‐stress enhances with increased PLLA weight ratio. The analysis of X‐ray diffractometry, differential scanning calorimetry, and Fourier‐transform infrared spectra demonstrated that the resultant nanofibers from electrospinning of PLLA‐gelatin solution are simple blends of these two components. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Properties of polyelectrolyte complex films of chitosan and gelatin

A series of chitosan–gelatin complexes was prepared by varying the ratio of constituents. Differential scanning calorimetry was used to determine the amount of the different states of water. The interaction between chitosan and gelatin was checked by IR and X-ray analysis and was related to mechanical strength. The results indicate that the water take-up of a chitosan–gelatin complex is depressed by strong interactions within networks. Chitosan can improve the tensile strength of complex films, and even with high water content these can keep appropriate tensile strength and higher elongation. © 1999 Society of Chemical Industry     

Preparation and characterization of hydroxyapatite/chitosan–gelatin network composite

A novel composite composed of hydroxyapatite (HA) and a network formed via cocrosslinking of chitosan and gelatin with glutaraldehyde was developed. Two preparation methods are described in detail. A porous material, with similar organic–inorganic constituents to that of natural bone, was made by a unique sol–gel method. The formation of the network in the presence of HA was characterized using IR analysis. The morphology of the composites was also examined using SEM. In addition, XRD was applied to estimate the change in the component crystal. The results indicate that the presence of HA does not retard the formation of the chitosan/gelatin network. On the other hand, the polymer matrix has hardly any influence on the high crystallinity of HA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2929–2938, 2000     

Novel pH,ion sensitive polyampholyte gels based on carboxymethyl chitosan and gelatin

Natural pH and ion sensitive polyampholyte gels were successfully prepared by blending carboxymethyl chitosan (CM‐chitosan) and gelatin using glutaraldehyde as crosslinking agent. Their swelling behaviour under the influence of pH and ionic strength of the solution has been studied, and molecular interaction and, morphology of the gels were investigated by infrared spectroscopy and scanning electron microscopy. At the isoelectric point (IEP) the blend gels shrunk most, and when pH deviated from the IEP they behaved as polycations or polyanions. A decrease in swelling degree (D_s) with rising NaCl concentration up to 0.15 M was observed for all gels, while addition of Ca²⁺ made them shrink due to formation of Ca²⁺ crosslinked bridges. The blended gels showed increasing sensitivity to pH and ionic strength as the weight fraction of CM‐chitosan increased. Two essential components seem to regulate the swelling behaviour of blended gel: the first is related to osmotic pressure difference caused by the redistribution of mobile ions; the second is related to the possible formation of interactions corresponding to hydrogen bonding and hydrophobic interactions. © 2003 Society of Chemical Industry     

Fabrication of protein‐doped PLA composite nanofibrous scaffolds for tissue engineering

BACKGROUND: Electrospinning is known as a novel fabrication method to form nanofibrous scaffolds for tissue‐engineering application. Previously, many natural biopolymers of protein have been electrospun. However, keratin has not attracted enough attention. In this study, keratin and gelatin were co‐electrospun with polylactide (PLA), respectively. RESULTS: The resulting nanofibers were characterized by a field emission scanning electron microscope (FE‐SEM), an attenuated total reflection‐Fourier transform infrared spectroscopy (ATR‐FTIR), and an electron spectroscopy for chemical analysis (ESCA). The biodegradation of mats in the presence of trypsin solution was studied. Cell attachment experiments showed that NIH 3T3 cells adhered more and spread better onto the PLA/keratin and PLA/gelatin nanofibrous mats than that onto the blank PLA mats. MTT and BrdU assay showed that PLA/keratin and PLA/gelatin nanofibrous mats could both accelerate the viability and proliferation of fibroblast cells as compared to PLA nanofibrous mats. CONCLUSION: The present study suggests that the introduction of gelatin and keratin can both improve cell‐material interaction, especially, the former is more effective. Copyright © 2008 Society of Chemical Industry     

Nanofibrous scaffold prepared by electrospinning of poly(vinyl alcohol)/gelatin aqueous solutions

A series of nanofibrous scaffolds were prepared by electrospinning of poly(vinyl alcohol) (PVA)/gelatin aqueous solution. PVA and gelatin was dissolved in pure water and blended in full range, then being electrospun to prepared nanofibers, followed by being crosslinked with glutaraldehyde vapor and heat treatment to form nanofibrous scaffold. Field emission scanning electron microscope (FESEM) images of the nanofibers manifested that the fiber average diameters decreased from 290 to 90 nm with the increasing of gelatin. In vitro degradation rates of the nanofibers were also correlated with the composition and physical properties of electrospinning solutions. Cytocompatibility of the scaffolds was evaluated by cells morphology and MTT assay. The FESEM images revealed that NIH 3T3 fibroblasts spread and elongated actively on the scaffolds with spindle‐like and star‐type shape. The results of cell attachment and proliferation on the nanofibrous scaffolds suggested that the cytotoxicity of all samples are grade 1 or grade 0, indicating that the material had sound biosafety as biomaterials. Compared with pure PVA and gelatin scaffolds, the hybrid ones possess improved biocompatibility and controllability. These results indicate that the PVA/gelatin nanofibrous have potential as skin scaffolds or wound dressing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improvement of mechanical properties and in vitro bioactivity of freeze-dried gelatin/chitosan scaffolds by functionalized carbon nanotubes

Functionalized multiwall carbon nanotubes (f-MWCNTs) were used to reinforce the freeze-dried gelatin (G)/chitosan (Ch) scaffolds for bone graft substitution. Two types of G/Ch scaffolds at a ratio of 2:1 and 3:1 by weight incorporated with 0.025, 0.05, or 0.1 and 0.2 or 0.4?wt% f-MWCNT, respectively, were prepared by freeze drying, and their structure, morphology, and physicochemical and compressive mechanical properties were evaluated. The scaffolds exhibited porous structure with pore size of 80–300 and 120–140?µm for the reinforced scaffolds of G/Ch 2:1 and 3:1, respectively, and porosity 90–93% which slightly decreased with an increase in f-MWCNTs content for both types. Incorporation of f-MWCNTs led to 11- and 9.6-fold increase in modulus, with respect to their pure biopolymer blend scaffolds at a level of 0.05?wt% for G/Ch 2:1 and 0.2?wt% for G/Ch 3:1, respectively. The higher content of f-MWCNTs resulted in loss of mechanical properties due to agglomeration. The highest value of compressive strength and modulus was obtained for G/Ch 2:1 with 0.05?wt% f-MWCNT as 411?kPa and 18.7?MPa, respectively. Improvement of in vitro bioactivity as a result of f-MWCNTs incorporation was proved by formation of a bone-like apatite layer on the surface of scaffolds upon immersion in simulated body fluid. The findings indicate that the f-MWCNT-reinforced gelatin/chitosan scaffolds may be a suitable candidate for bone tissue engineering.     

壳聚糖/聚氧化乙烯静电纺丝工艺研究

采用聚氧化乙烯(PEO)与壳聚糖(CS)混合配制PEO/CS的稀醋酸溶液,进行静电纺丝,制得PEO/CS纳米纤维毡.考察了静电纺丝工艺条件对纤维直径和形貌的影响,并对PEO/CS纳米纤维毡进行了形态、结构、结晶性能、亲水性能等方面的表征.结果表明:PEO/CS纳米纤维毡的静电纺丝的最佳参数值为PEO/CS质量比为70/...     

MTGase反胶束纯化及其催化合成壳聚糖胶原改性物的展望

综述了微生物转谷氨酰胺酶（MTGase）的性质、用途及反胶束萃取纯化效果,展望了用MTGase催化合成等日化用新功能性原料的可行性及其前景。