Photocurable antimicrobial silk‐based hydrogels for corneal repair

Abstract

Corneal transplantation is the current gold standard treatment to restore visual acuity to patients with severe corneal diseases and injuries. Due to severe donor tissue shortage, efforts to develop a corneal equivalent have been made but the challenge remains unmet. Another issue of concern in ocular surgery is the difficult instillation and fast drainage of antibiotic ocular eye drops as bacterial infections can jeopardize implant success by delaying or impairing tissue healing. In this study, we developed antimicrobial silk‐based hydrogels that have the potential to be photoactivated in situ, fully adapting to the corneal injury shape. Gentamicin‐loaded methacrylated‐silk (SilkMA) hydrogels were prepared within minutes using low UV intensity (3 mW/cm2). SilkMA gels provided a Young's modulus between 21 and 79 kPa together with a light transmittance spectrum and water content (83%–90%) similar to the human cornea. Polymer concentration (15%–25%) was found to offer a tool for tailoring the physical properties of the hydrogels. We confirmed that the methacrylation did not affect the material's in vitro degradation and biocompatibility by observing fibroblast adhesion and proliferation. Importantly, agar diffusion tests showed that the synthesized hydrogels were able to inhibit Staphylococcus aureus and Pseudomonas aeruginosa growth for 72 h. These characteristics along with their injectability and viscoelasticity demonstrate the potential of SilkMA hydrogels to be applied in several soft tissue engineering fields. As such, for the first time we demonstrate the potential of photocurable antimicrobial SilkMA hydrogels as a novel biomaterial to facilitate corneal regeneration.

Tunable Light-Actuated Interpenetrating Networks of Silk Fibroin and Gelatin for Tissue Engineering and Flexible Biodevices

“…21 Some studies have tried to harmonize the intrinsic properties of SF and gelatin as composites in the form of bioinks for 3D printing and hydrogel cell scaffolds. 55 To the best of our knowledge, free-standing thin-film constructs have not been demonstrated to date. Photofibrogel, with its multiscale processability and favorable mechanical properties, could provide routes to achieve directed cell growth and promote organization into mature tissue constructs.…”

“…Derivatives such as GelMA and Matrigel are widely used for cell culture and also lack mechanical stability and degrade easily . Some studies have tried to harmonize the intrinsic properties of SF and gelatin as composites in the form of bioinks for 3D printing and hydrogel cell scaffolds . To the best of our knowledge, free-standing thin-film constructs have not been demonstrated to date.…”

Advances in Biomaterials for Corneal Regeneration

“…Gentamicin-loaded methacrylated-silk (SilkMA) hydrogels adopted the corneal injury shape and gelled within a few minutes upon exposure to low-intensity UV. The mechanical strength, transparency, and water content approached those of the human cornea, and hydrogel inhibited the growth of Staphylococcus aureus and Pseudomonas aeruginosa for up to 72 h [41]. Silk-fibroin-based films (SF) were also complexed with lysophosphatidic acid (LPA) to form a functionalized graft for corneal endothelial cell (CEnCs) regeneration.…”

The Year 2022 in biomaterials research: A perspective from the editors of six leading journals

“…Silk fibroin is under broad examination for use as a corneal implant material due to its transparency, tunability, and biodegradability. To address the potential challenge of infection with corneal implantation, the team of Anita K. Ghag (University of Birmingham, UK) created a methacrylated silk (SilkMA), which was loaded with gentamicin and rapidly crosslinked with ultraviolet light 73 . The mechanical properties of the construct were readily tunable by modulating the polymer concentration and matched those or the native cornea.…”