Abstract
Purpose :
Corneal scarring and vascularization are a major cause of blindness worldwide, second only to cataract. This study aims to develop a novel biodegradable adhesive to be used in the treatment of keratolysis (active corneal melting) and perforations, eradicating the need to use toxic materials such as cyanoacrylates for sealing wounds. Due to its excellent biocompatibility, optical clarity and viscoelastic behaviour, silk fibroin (SF, a structural protein) is a promising material for ocular tissue engineering. Fibroin contains amino and carboxylic groups that can be modified with several functional groups. In order to achieve an adhesive which may be polymerised in situ, this work focuses on SF methacrylation using glycidyl methacrylate (GMA).
Methods :
Degummed SF was dissolved in lithium bromide solution at 60°C. GMA was added to the SF solution at a rate of 0.5 mL/min, and allowed to react for 3h at 60°C. Methacrylated-silk fibroin (SF-MA) was then dialysed against deionised water for 5 days. Finally, the solution was lyophilised for 2 days to generate a white porous foam. The degree of methacrylation (DM%) was quantified by proton nuclear magnetic resonance (1H-NMR). Phase and baseline correction were applied before integrating the peaks of interest.
Results :
Fibroin was methacrylated through the reaction with GMA with the free amines in the lysines introducing vinyl groups in the SF polymer chain. This modification was confirmed by the reduction of the lysine signal at d= 3 ppm and the appearance of the vinyl group signal at d= 6.2 ppm (Fig. 1). SF-MA with low (5.4 ± 0.6%) and medium (10.6 ± 0.2%) were obtained by varying the amount of GMA added from 4 to 10% (v/v).
Conclusions :
In situ forming adhesives are very attractive materials due to their ability to adapt to the shape of the keratolysis or perforation before being cured. Importantly, the mechanical properties of SF-MA are controllable by changing the DM% and the polymer concentration. The application of biocompatible adhesives that provide scaffolds for enhanced tissue regeneration, could reduce the demand of human corneal transplants, and the use of cyanoacrylates and sutures.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.