Flexible PEGDA-gelatin hydrogel for optical fibers with enhanced electromechanical properties and initial insights into antimicrobial activity and light transmission.

This study presents optical fibers made of PEGDA-gelatin hydrogels (PG hydrogels) for biomedical and optoelectronic applications, with a focus on flexibility, biocompatibility and performance. These fibers, produced by UV polymerization, have a uniform, coreless structure with adjustable mechanical and optical properties. Among the formulations, PG4 (a PEGDA-to-gelatin ratio of 1:2) showed the best balance between conductivity, stretchability, and transparency due to its stronger cross-linking. Mechanical tests confirmed the flexibility and stability of the material under repeated deformation and temperature cycling, while optical tests demonstrated effective light transmission through biological tissue models. PG4 hydrogel achieved a light transmission of approximately 63 % at 550 nm, comparable to PEG-based systems and higher than alginate-based fibers. It also exhibited antimicrobial activity against E. coli and S. aureus, maintaining its structural integrity for 10 days under ambient conditions and for 14 days under high humidity. Biodegradability studies indicated a mass loss of ~55 % over 14 days, suggesting potential as an absorbable material. While PEGDA and gelatin are widely recognized for their biocompatibility, future work will include direct cytocompatibility and implantation studies to further validate their suitability for long-term biomedical use.