@article {20268, title = {Exploring the Gelation Mechanisms and Cytocompatibility of Gold (III)-Mediated Regenerated and Thiolated Silk Fibroin Hydrogels}, journal = {Biomolecules}, volume = {10}, year = {2020}, month = {2020-03-18 00:00:00}, pages = {1-14}, publisher = {MDPI AG}, abstract = {

Accelerating the gelation of silk fibroin (SF) solution from several days or weeks to minutes
or few hours is critical for several applications (e.g., cell encapsulation, bio-ink for 3D printing, and
injectable controlled release). In this study, the rapid gelation of SF induced by a gold salt (Au3+) as
well as the cytocompatibility of Au3+-mediated SF hydrogels are reported. The gelation behaviors
and mechanisms of regenerated SF and thiolated SF (tSF) were compared. Hydrogels can be obtained
immediately after mixing or within three days depending on the types of silk proteins used and
amount of Au3+. Au3+-mediated SF and tSF hydrogels showed different color appearances. The color
of Au-SF hydrogels was purple-red, whereas the Au-tSF hydrogels maintained their initial solution
color, indicating different gelation mechanisms. The reduction of Au3+ by amino groups and further
reduction to Au by tyrosine present in SF, resulting in a dityrosine bonding and Au nanoparticles
(NPs) production, are proposed as underlying mechanisms of Au-SF gel formation. Thiol groups
of the tSF reduced Au3+ to Au+ and formed a disulfide bond, before a formation of Au+-S bonds.
Protons generated during the reactions between Au3+ and SF or tSF led to a decrease of the local
pH, which affected the chain aggregation of the SF, and induced the conformational transition of SF
protein to beta sheet. The cytocompatibility of the Au-SF and tSF hydrogels was demonstrated by
culturing with a L929 cell line, indicating that the developed hydrogels can be promising 3D matrices
for different biomedical applications.

}, keywords = {Cytocompatibility, Gold, hydrogel, Silk Fibroin, thiolated silk fibroin}, issn = {2218-273X}, doi = {10.3390/biom10030466}, url = {https://www.mdpi.com/2218-273X/10/3/466}, author = {Laomeephol, C. and Ferreira, H. and Yodmuang, S. and Reis, R. L. and Damrongsakkul, S. and Neves, N. M.} }