The blend films showed nonporous rough surface. These globular structures become smaller as the SF content increased. This may be due to water absorption ability of CS that caused irregular bulging morphology selleck MEK162 after drying as was also shown by the swelling property of the blend. This rough surface was expected to support adhesion of fibroblast cells as was mentioned previously [36]. FTIR spectroscopy was used to identify functional groups of CS and SF and their interaction between these two components in the blend films. SF film was simultaneously composed of both ��-sheet and random coil structure. The ��-sheet structure of SF film may be enhanced by the effect of acidic solvent during the preparation process [31]. In addition, transition from random coil to ��-sheet of SF was increased by adding CS which was demonstrated by shifting of amide bands of SF.

The conformation change of SF was supported by the interaction between CS and SF. As was found in the spectra of the blend films, the absorption band of the C=O and N-H group of CS disappeared and the amide bands of SF showed ��-sheet structure by shifting amide I band of SF to lower wave number and a new absorption band at higher wave number of amide III was observed [31, 32]. This indicated intermolecular interaction between SF and CS. A previous report has shown that SF could form ��-sheet structure by hydrogen bond between amide groups of SF and N-H of CS [37]. It is noticeable that the CF 1:2 blend films markedly exhibited ��-sheet structure corresponding with the previous report [33, 34].

Intermolecular interaction between CS and SF was also demonstrated in thermal behavior of the blend films by increasing the decomposition temperature and decreasing moisture evaporation temperature. The reduction of the moisture evaporation temperature may be caused by the conformation change of SF from random coil to ��-sheet structure that enhanced the intermolecular hydrogen bonds between SF and CS molecules and reduced the interaction between SF and water. The downward shifting of the moisture evaporation which reaches maximum with the CF 1:2 blend film corresponded with the FTIR analysis that structural conformation was markedly displayed in this blend proportion.The scaffold should have sufficient mechanical properties to maintain Cilengitide its structure during cell growth and implantation process by its nature of SF that normally has high mechanical strength. However, brittleness of a pure SF film is the limitation, and blending with CS is an alternative to improve the property of fibroin film.