Enhancing the versatility of photocrosslinkable silk fibroin using an eco-friendly solvent

Silk fibroin (SF), known for its biocompatibility and versatility, has been widely studied in tissue engineering and biomedical devices. The modification of silk fibroin with photoreactive groups has been used to create novel biomaterials that undergo a liquid-to-solid transition upon exposure to light, enabling precise control over structure formation, pore geometry, and degradation. This advancement of photofibroin (PF) has been shown for the biofabrication of hydrogels, 3D scaffolds, and micro-patterned surfaces suitable for biomedical applications, including tissue scaffolds and bioelectronics. Here, we present a further improvement using a water based ternary solvent of calcium chloride-ethanol-water (Ajisawa reagent (AR)), to dissolve photofibroin, offering a sustainable alternative to previously used organic solvents. PF in AR is shown to be compatible with various light-based manufacturing techniques including soft lithography, photolithography, and 3D printing, enabling the fabrication of multiscale structures with high fidelity. The gels formed demonstrate excellent cytocompatibility, supporting cell adhesion and growth without additional coatings, making them ideal for regenerative medicine. The integration of conductive polymers, such as PEDOT:PSS as a 3D printable conducting gel opens possibilities for bioelectronics. The research represents a significant step forward in employing the versatile photofibroin as a sustainable, high-performance biomaterial for diverse applications.