Synergistic effects of ionic photosensitizers and silver nanoparticles in PEGDA/gelatin hybrid hydrogels for advanced...

Photodynamic therapy offers a promising approach for combating multidrug-resistant bacterial infections. In response to the growing challenge of antibiotic resistance, this study introduces PEGDA/gelatin hybrid hydrogels as smart, multifunctional platforms for photodynamic therapy. These hydrogels were specifically designed to function as both wound dressings and photosensitizer carriers, addressing key clinical needs such as optical transparency, skin-like mechanical properties, moisture management, and controlled release. Toluidine blue O and Eosin Y were effectively released and retained their photodynamic activity under light exposure. Antibacterial testing against Escherichia coli and Staphylococcus aureus revealed that silver nanoparticles alone were insufficient for robust antimicrobial action. However, when combined with photosensitizers, a remarkable enhancement in bacterial inactivation was observed, driven by light-induced synergistic effects. Specifically, the antibacterial efficiency of PEGDA/gelatin hybrid hydrogels containing both Eosin Y and silver nanoparticles increased by 97% against Escherichia coli and 98% against Staphylococcus aureus compared to hydrogels containing Eosin Y alone. This enhancement can be attributed to the anionic nature of Eosin Y, its superior diffusion capacity, and its effective interaction with silver nanoparticles and disrupted bacterial membranes. In contrast, despite the strong photodynamic potential of toluidine blue O, its interaction with silver nanoparticles may have limited its availability for effective microbial targeting. These findings underscore the promise of integrating photosensitizers with silver nanoparticles in a hydrogel matrix to create next-generation wound dressings capable of precise, light-activated antimicrobial action. This approach represents a compelling alternative or supplement to conventional antibiotics.