Gelatin nanofibers can be used in the development of a biomimicking artificial extra cellular matrix(ECM) for tissue engineering, wound healing dressings and drug release. However, gelatin nanofibers are water soluble and have weak mechanical strength. Two different cross-linking methods for preparing gelatin nanofibers were used to render gelatin nanofibres insoluble: 1) UV radiation for modified gelatin nanofibers by trans-cinnamic acid; and 2) electrospun gelatin nanofibers cross-linked with genipin. A photo cross-linking method was used to examine the effects of ultraviolet (UV) radiation on the modified gelatin nanofiber scaffolds. A modified gelatin solution containing gelatin, trans-cinnamic acid and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) at a molar ratio of 1:3:30 was prepared. The results showed that the degree of modification in gelatin molecules was 14.5 groups per mol. The modified gelatin was dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol at 20%(w/v) and nanofibrous meshes were obtained by electrospinning. After drying, the nanofibrous meshes were exposed to a commercial germicide UV (=254 nm) lamp for different times. The swelling ratio of each nanofibrous mesh was decreased from 195% to 105% with increasing UV exposure time from 1 h to 10 h. A cross-linking agent method was used to evaluate the effects of the cross-linked gelatin nanofiber scaffolds with genipin. The swelling ratios decreased from 725% to 445% with increasing genipin solution concentration from 0.5%(w/ v) to 2%(w/v). The results of the cell culture suggest that cross-linking gelatin nanofibers with 0.5%(w/v) genipin improves the level of cell proliferation with increasing cell culture time from 1 day to 5 days. Moreover, the cell viability of each nanofiber increased with increasing cell culture time. However, the cell viability decreased with increasing genipin solution concentration.

The effects of various processing parameters of electro spinning such as concentration, applied voltage, distance from needle to collector on the morphology(especially fiber diameter) of nanofiber matrix was investigated in this study. We found out the concentration of polymer solution was the key parameter to control the fiber diameter. Such a difference on surface morphology of electro spun nanofiber matrix under various processing parameters will show the different behaviors on protein adsorption on the surface contacting with body fluid. Consequently, this results different cell motions on the matrix used on tissue engineering. To evaluate the adsorption of proteins on the surface of sheet type nanofiber matrix, matrix obtained by electro spinning were immersed in FITC labeled proteins solutions. And then, we confirmed adsorption of proteins using laser scanning confocal microscopy (LSCM). The quantitative analysis of adsorbed proteins was also investigated by UV spectroscopy.

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