The objective of the present studywas to investigate the properties of chitosan–gelatin membranes or scaffolds, which were modified byincorporation of hyaluronic acid in the surface or bulk phase through co-crosslinking with N;N-(3-dimethylaminopropyl)-N0-ethyl carbodiimide (EDC) and N-hydroxysuccinimide (NHS) in 2-morpholinoethane sulfonic acid (MES) buffer. The comparative studyon properties of surface modification (HA(S)) and polyblend membranes (HA(C)) revealed that gelatin was enriched on the surface of HA(C), while hyaluronic acid was enriched on the surface of the HA(S). The HA(S) membranes made by surface modification method had a characteristic surface morphology. The corresponding scaffolds were prepared through freezedrying. The incorporation of hyaluronic acid improved flexibility and fibroblasts adhesion, while slowing down the rate of biodegradation of chitosan-gelatin scaffold. Human fibroblasts adhered and proliferated well on the membranes or scaffolds in vitro.

Chitosan-gelatin hybrid polymer network scaffolds were prepared via the freeze-drying technique by using the ice microparticle as a porogen. Monolayer and bilayer scaffolds were obtained by using different pre-freezing methods. The novel bilayer scaffolds were prepared via contact with 561C lyophilizing plate directly, then lyophilized. The properties of chitosan-gelatin scaffolds, such as microstructure, physical and mechanical and degradable properties, were studied. These results suggested that the porosity and pore size of the scaffolds could be modulated with thermodynamic and kinetic parameters of ice formation. The scaffolds prepared from chitosan and gelatin can be utilized as a promising matrix for tissue engineering.

Glucose was oxidized to generate a glucose dialdehyde and chitosan (CS) was hydrophobically modified with butyl bromide, octyl bromide and dexyl bromide. The analysis of IR and X-ray diffraction results of CS derivatives confirms that the hydrogen bonds and crystallinity were weakened by the incorporation of pendant alkyl. The permeability coefficient P and diffusion coefficient D for model drug vitamin B2 through oxidized glucose-crosslinked alkylated CS membrane were determined under different pH media. The results show that for the same alkylated CS in different pH media, P and D decrease withan increase in pH; for different alkylated CSs in acidic media, P and D diminish with the increase in the length of alkyl side, which is supposedly originated from the enhancement of hydrophobicity. In alkali medium, P and D show a rising trend with the increase in the length of alkyl chain, which might be related to the loose stacking of network as it occurs to shrink in alkali medium. The preliminary cytotoxicity assay indicates that oxidized glucose-crosslinked alkylate CS membrane is non-toxic in vitro.

A novel biodegradable hydroxyapatite/chitosan-gelatin network (HA/CS-Gel) composite of similar composition to that of normal human bone was prepared as a three-dimensional biomimetic scaffold by phase separation method for bone tissue engineering. Changing the solid content and the compositional variables of the original mixtures allowed control of the porosities and densities of the scaffolds. The HA granules were dispersed uniformly in the organic network with intimate interface contact via pulverizing and ultrasonically treating commercial available HA particles. Scaffolds of 90.6% porosity were used to examine the proliferation and functions of the cells in this three-dimensional microenvironment by culturing neonatal rat caldaria osteoblasts. Histological and immunohistochemical staining and scanning electron microscopy observation ndicated that the osteoblasts attached to and proliferated on the scaffolds. Extracellular matrices including collagen I and proteoglycan-like substrate were synthesized, while osteoid and bone-like tissue formed during the culture period. Furthermore, the cell/scaffold constructs had good biomineralization effect after 3 weeks in culture.

The objective of this study was to modify the surface of poly(d,l-lactic acid) (PDLLA) with different molecular weight of silk fibroins, and assess the effects of the modified surfaces on the functions of rat osteoblasts cultured in vitro. The properties of the modified PDLLA surface and the control one were investigated by contact angle and electron spectroscopy for chemical analysis (ESCA). The former indicated the variation of hydrophilicity and the latter suggested that the modified PDLLA film using silk fibroin is enriched with nitrogen atoms. The biocompatibility of the PDLLA film may be altered and in turn affects the seeded cell functions Therefore, attachment and proliferation of osteoblasts seeded on the modified PDLLA films and the control one were examined. Cell morphologies on these films were studied by scanning electron microscopy (SEM) and cell viability was evaluated by MTT assay. In addition, differentiated cell function was assessed by measuring the alkaline phosphatase (ALP) activity. These results suggest that the silk fibroin-modified PDLLA surface can improve the interaction between osteoblasts and the PDLLA films.