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Structure and properties of biomedical films prepared from aqueous and acidic silk fibroin solutions

journal contribution
posted on 01.04.2011, 00:00 authored by Rangam RajkhowaRangam Rajkhowa, B Levin, S Redmond, Luhua LiLuhua Li, Lijing Wang, Jagat Kanwar, M Atlas, Xungai WangXungai Wang
Silk fibroin films are promising materials for a range of biomedical applications. To understand the effects of casting solvents on film properties, we used water (W), formic acid (FA), and trifluoroacetic acid (TFA) as solvents. We characterized molecular weight, secondary structure, mechanical properties, and degradation behavior of cast films. Significant degradation of fibroin was observed for TFA-based film compared to W and TA-based films when analyzed by SDS-PAGE. Fibroin degradation resulted in a significant reduction in tensile strength and modulus of TFA-based films. Compared to water, TFA-based films demonstrated lower water solubility (19.6% vs. 62.5% in 12 h) despite having only a marginal increase in their ß-sheet content (26.9% vs. 23.7%). On the other hand, FA-based films with 34.3% ß-sheet were virtually water insoluble. Following solubility treatment, ß-sheet content in FA-based films increased to 50.9%. On exposure to protease XIV, water-annealed FA-based films lost 74% mass in 22 days compared to only 30% mass loss by ethanol annealed FA films. This study demonstrated that a small variation in the ß-sheet percentage and random coil conformations resulted in a significant change in the rates of enzymatic degradation without alteration to their tensile properties. The film surface roughness changed with the extent of enzymatic hydrolysis.

History

Journal

Journal of biomedical materials research : Part A

Volume

97A

Issue

1

Pagination

37 - 45

Publisher

John Wiley & Sons

Location

Hoboken, N.J.

ISSN

1549-3296

eISSN

1552-4965

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2011, Wiley Periodicals, Inc.