Photocrosslinking of Silk Fibroin Using Riboflavin for Ocular Prostheses

Abstract

A novel method to photocrosslink silk fibroin protein is reported, using riboflavin (vitamin B2) as a photoinitiator and the mechanism of crosslinking is determined. Exposure of riboflavin-doped liquid silk solution to light results in the formation of a transparent, elastic hydrogel. Several applications for this new material are investigated including corneal reshaping to restore visual acuity and photolithography.

Riboflavin photo‐cross‐linking method for improving elastin stability and reducing calcification in bioprosthetic heart valves

“…Riboflavin photo‐cross‐linking has been used for the chemical cross‐linking of silk fibroin, collagen, and alginate . HPA conjugated gelatin was reported to make hydrogels, which made use of HPA‐induced phenol groups for cross‐linking .…”

“…Photo‐cross‐linking using photoinitiator riboflavin 5’‐monophosphate was performed by similar methods as described in previous studies . HPA/TRA conjugated pericardiums (N = 6 in each group) were soaked in different concentrations of riboflavin 5’‐monophosphate solutions (2, 20, 50 mM) supplemented with 1% EGCG at 37°C with constant shaking at 150 rpm on an orbital shaker (SK‐O180‐E, DRAGONLAB, Beijing, China) for 24 hours.…”

“…HPA/TRA conjugated pericardiums (N = 6 in each group) were soaked in different concentrations of riboflavin 5’‐monophosphate solutions (2, 20, 50 mM) supplemented with 1% EGCG at 37°C with constant shaking at 150 rpm on an orbital shaker (SK‐O180‐E, DRAGONLAB, Beijing, China) for 24 hours. Then samples were cross‐linked under UV light (CL‐1000 Ultraviolet Crosslinker, 100 µJ/cm 2 ) for 40 minutes . The efficient feeding ratio of riboflavin 5’‐monophosphate was determined by collagenase enzymatic degradation tests.…”

“…Riboflavin photo‐cross‐linking has been used in many biomaterials’ application . Riboflavin 5’‐monophosphate, a water‐soluble variant of riboflavin, has been used to catalyze the transition of a liquid silk solution to a highly elastic hydrogel in the presence of light . Collagen‐based scaffold prepared by riboflavin photo‐cross‐linking has been used for meniscus tissue engineering .…”

Deformable and conformal silk hydrogel inverse opal

“…UVC light induces [2π + 2π] cycloadditions between the stilbene units, whereas the radicals generated in the silk tethers undergo dityrosine bonding (for details, see Supporting Information and Fig. S1) (24,25). The rate of photo-cross-linking is increased by the aromaticity of the side chain that silk possesses in abundance.…”