Fabrication and Evaluation of Porous Keratin/chitosan(KCS) Scaffolds for Effectively Accelerating Wound Healing

Objective To develop a dressing with desired antibacterial activity, good water maintaining ability and mechanical properties for wound healing and skin regeneration. Methods The chitosan with different concentrations were added in keratin solution to form porous keratin/chitosan（KCS） scaffolds. The morphological characteristics, chemical composition, wettability, porosity, swelling ratio and degradation of the scaffolds were evaluated. The antibacterial activity was tested by using S. aureus and E. coli suspension for 2 h. And L929 fibroblast cells culture was used to evaluate the cytotoxicity of the KCS scaffolds. Results The adding of chitosan could increase the hydrophobicity, decrease porosity, swelling ratio and degradation rate of the KCS porous scaffolds. Mechanical properties of KCS scaffolds could be enhanced and well adjusted by chitosan. KCS scaffolds could obviously decrease bacteria number. The proliferation of fibroblast cells in porous KCS patch increased firstly and then decreased with the increase of chitosan concentration. It was appropriate to add 400 μg/m L chitosan to form porous KCS scaffold for achieving best cell attachment and proliferation compared with other samples. Conclusion The porous KCS scaffold may be used as implanted scaffold materials for promoting wound healing and skin regeneration.

VE TPGS-Loaded Silk Fibroin / Hydroxybutyl Chitosan Nanofibrous Scaffolds for Skin Care Application

Vitamin E( VE) is an ideal antioxidant and a stabilizing agent in biological membranes. In this study,silk fibroin( SF) /hydroxybutyl chitosan( HBC) nanofibrous scaffolds are loaded with VE tocopherol polyethylene glycol 1000 succinate( VE TPGS) via electrospinning. SEM images show that the average nanofibrous diameter has no significant difference when the content of VE TPGS increases to 4. 0%( SF / HBC). However,the average nanofibrous diameter decreases largely to 200 nm when the VE TPGS content reaches 6. 0%. Furthermore,VE TPGS presents a sustained release behavior from the nanofibrous scaffolds. Cell viability studies of mouse skin fibroblasts( L929) demonstrate that VE TPGS loaded SF / HBC nanofibrous scaffolds present good cellular compatibility.Moreover,the incorporation of VE TPGS could strengthen the ability of SF / HBC nanofibrous scaffolds on protecting the cells against oxidation stress using the Tertbutyl hydroperoxide( t-BHP)-induced oxidative injury model. Therefore,VE TPGS-loaded SF /HBC nanofibrous scaffolds might be potential candidates for personal skin care,wound dressing and skin tissue engineering scaffolds.

Using PEG as Progen to Preparate Chitosan Scaffold for Tissue Engineering

Tissue engineering basically made up growing the relevant cell in vitro and extracellular matrix. A major goal of tissue engineering is to preparate porous three dimension scaffold for cell proliferate, migrate, differention and to form the structure of desirable tissue and organ. In this study, the effects of various content and macromolecular weight of PEG to chitosan were investigated and evaluated. The pore morphology of chitosan was controlled by changing the concentration and macromolecular weight of PEG. Chitosan porous scaffold has interconecting porosity. The pore morphology can be controlled with varying PEG concentration and macromolecular weight. The pore size is between 10～50 urn, the degree of swelling in water is 85.70 % .

Influence of chitosan nanofiber scaffold on porcine endogenous retroviral expression and infectivity in pig hepatocytes

AIM: To investigate the influence of chitosan nanofiber scaffold on the production and infectivity of porcine endogenous retrovirus (PERV) expressed by porcine hepatocytes. METHODS: Freshly isolated porcine hepatocytes were cultured with or without chitosan nanofiber scaffold (defined as Nano group and Hep group) for 7 d. The daily collection of culture medium was used to detect reverse transcriptase (RT) activity with RT activity assaykits and PERV RNA by reverse transcription-polymerase chain reaction (PCR) and real time PCR with the PERV specific primers. And Western blotting was performed with the lysates of daily retrieved cells to determine the PERV protein gag p30. Besides, the in-vitro infectivity of the supernatant was tested by incubating the human embryo kidney 293 (HEK293) cells. RESULTS: The similar changing trends between two groups were observed in real time PCR, RT activity assay and Western blotting. Two peaks of PERV expression at 10H and Day 2 were found and followed by a regular decline. No significant difference was found between two groups except the significantly high level of PERV RNA at Day 6 and PERV protein at Day 5 in Nano group than that in Hep group. And in the in-vitro infection experiment, no HEK293 cell was infected by the supernatant. CONCLUSION: Chitosan nanofiber scaffold might prolong the PERV secreting time in pig hepatocytes but would not obviously influence its productive amount and infectivity, so it could be applied in the bioartificial liver without the increased risk of the virus transmission.

Aligned carbon nanotube containing scaffolds for neural tissue regeneration

Neuropathologies include the deterioration and damage of the nervous system,especially neurons present in the brain,spinal cord and peripheral nervous system.Damage or alternations in neurons makes their structure and functionality abnormal.Every year over 90,000 people get affected by neurodegenerative diseases in the USA.Among all the neurological pathologies,

APPLICATION OF CHITOSAN-BASED BIOMATERIALS IN BIOARTIFICIAL LIVE

Bioart,ficial liver support system （BALS） has the potential to provide temporary support for patients with fulminant hepatic failure and consist of viable hepatocytes and scaffolding materials for hepatocytes attachment. Various scaffolding materials are used in BALS, including chitosan, which is easily obtained by deacetylation of chitin and widely applied in biomedical applications. In this paper, we introduce and discuses chitosan-based biomaterials for BALS application.

Cytocompatible 3D chitosan/hydroxyapatite composites endowed with antibacterial properties:toward a self-sterilized bone tissue engineering scaffold

Bone tissue scaffolds based on bioactive polymer–hydroxyapatite composites have caused infections that seriously limit their extended application. In this study, we proposed a practical ion substitution method to synthesize in situ silver phosphate on the surface of a two-level, threedimensional chitosan/nano-hydroxyapatite scaffold. A release test of silver ions in a phosphate buffered saline(PBS) solution was performed to demonstrate that silver ions were released continuously from the silver phosphate during the initial 6 days of the study. The antibacterial property and cytocompatibility of the scaffolds treated with different concentrations of silver nitrate solution were assessed by in vitro assays with Escherichia coli and MC3T3-E1, respectively. The ability of the silver-containing scaffolds to induce bacteriostasis was confirmed by the inhibition zone(15 mm) and high bactericidal rate([99 %). Cell proliferation, morphology and the alkaline phosphatase activity of MC3T3-E1 cultured on the scaffold with low silver phosphate contents were comparable with those cultured on control samples.

Bilayered HA/CS/PEGDA hydrogel with good biocompatibility and self-healing property for potential application in osteochondral defect repair

The fabrication of osteochondral tissue engineering scaffolds comprised of different layers is a big challenge. Herein, bilayers comprised of double network hydrogels with or without nano hydroxyapatite （HAp） were developed by exploiting the radical reaction of poly（ethylene glycol） diacrylate （PEGDA） and the Schiff-base reaction of N-carboxyethyl chitosan （CEC） and oxidized hyaluronic acid sodium （OHA） for osteochondral tissue engineering. The bilayered osteochondral scaffold was successfully fabricated based on the superior self-healing property of both hydrogels and evaluated by scanning electron microscopy, macroscopic observation and mechanical measurements. In addition, the hydrogels exhibited good biocompatibility as demonstrated by the in vitro cytotoxicity and in vivo implantation tests. The results indicated that the bilayered hydrogel had great potential for application in osteochondral tissue engineering.