Enhancing the adhesiveness capacity of tissue adhesives: Exploring the impact of silk fibroin concentration and curing time on the efficacy of corneal adhesives

The current study delved into developing biocompatible silk fibroin (SF) hydrogel-based adhesives and assessed the effect of various concentrations of SF and the visible light exposure duration during the riboflavin-mediated photo-crosslinking process to promote the in vitro/ex vivo performance of them as an ocular tissue adhesive. To accomplish this purpose, the SF solution with high adhesion features that was extracted from silk cocoons underwent exposure for durations of 1, 2, and 4 min, with varying SF concentrations (7.5 %, 15 %, and 22.5 % w/ v). The physicochemical properties of the SF adhesives, such as mechanical strength and biological adhesion behaviors, were enhanced by the increase in SF contents and irradiation time that were investigated by the characterizations of the adhesives using various techniques, which was attributed to the high density of dityrosine and beta-sheet crosslinking agents in the adhesive network. Furthermore, the interaction between tyrosine residues in SF and ocular aqueous humor led to the formation of covalent di-tyrosine crosslinking, which improved the performance of the developed corneal adhesives. SF adhesives exhibited nontoxicity behaviors towards human corneal fibroblast cell lines (HCFs), and findings of DAPI/Actin and PrestoBlue assays revealed the readily adhesion and proliferation of HCFs over SF adhesives, which confirmed their biocompatibility and potential for use in corneal tissue engineering applications.