(374f) Preparation and Characterization of SF-PLGA Film By TIPS Method

Besides excellent biocompatibility, a useful tissue engineering scaffold should provide suitable micropores and fibrous structure to mimic the natural extracellular matrix, inducing desired cellular activities and guiding tissue regeneration. Silk fibroin and PLGA have been widely used in tissue engineering because of excellent biocompatibility and mechanical property. In this work, a porous and fibrous silk fibroin (SF)-PLGA [poly(lactic-co-glycolic acid)] scaffold prepared by thermally induced phase separation (TIPS) is described.

Firstly, to study the effects of volume ratio of hexafluoro-2-propanol (HFIP)/water (v/v), concentration of (SF+PLGA)/solvent (w/v), weight ratio of SF/PLGA (w/w) and phase separation temperature (PST) on the pore size and porosity of SF/PLGA scaffolds, single-factor experiments were performed to determine suitable ranges of the four factors. Based on that, a 2⁴ factorial experiment was used to analyze the effect of these parameters on the pore size and porosity. The results showed that the porous and fibrous scaffold with suitable pore size (25.53±2.18 μm) and high porosity (84.83±9.05%) could be made by the TIPS method when HFIP/water volume ratio is 2.25/1 (v/v), concentration of (SF+PLGA)/solvent (w/v) is 0.09 g/mL, weight ratio of SF/PLGA is 5/8 (w/w) and phase separation temperature is -50°C. SEM photographs showed the microfibrous and nanofibrous structures could be made successfully. Solvent residue analysis showed that the HFIP residue was 300 ppm, which was proved to be no cytotoxicity. FTIR and XRPD results showed that the structure of SF changed after TIPS process.

Secondly, based on the results of 2⁴ factorial experiments, scaffolds with different weight ratios of SF/PLGA were studied to optimize materials with better properties for skin dressings. Mechanical properties showed that the range of tensile strength is 1035±306 to 75±21 kPa, the tensile strain range is 34.34±13.62~119.10±16.82%. The results of water vapor permeability, water absorption rate, and water loss rate showed that the optimal weight ratio of SF/PLGA is 8/8 (Level: 1), producing a material that can absorb wound skin exudate to prevent infection and maintain wound humidity. The water vapor transmission rate is 5591.88±56.70 g/m²/day, the maximum equilibrium water absorption rate is 72.2%.

Finally, the cytocompatibility of scaffold on HESF cells was studied. The results showed that the scaffolds have good biocompatibilities and no cellular toxicity through relative growth rate, AO/EB staining and cell apoptosis rate. Furthermore, cell adhesion and proliferation results suggested that the optimal weight ratio of SF/PLGA was 8/8 (Level: 1), which resulted in highest cell adhesion and proliferation.

Acknowledgements: Financial supports from NSFC (31000441 and 31170939), Natural Science Foundation of Fujian Province (2013J01189), Program for Prominent Young Talents in Fujian Province University (JA12004), China Postdoctoral Science Foundation (2014M551833), the Scientific Research Foundation for the Returned Overseas Chinese Scholars (State Education Ministry) and the Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University (ZQN-PY108) are gratefully acknowledged.