Antibacterial and cytotoxicity enhancement of 316L stainless steel alloy via epsilon-polylysine and graphene oxide/silver composite coating

Background: The rising demand for dental and biomedical equipment with effective antibacterial qualities requires the development of highly functional coatings. Aim: This study investigated the effectiveness of coating 316L stainless steel (SS) alloy with ε- polylysine (ε- PLL) and graphene oxide (GO) /silver (Ag) nanoparticle (NP) composites to enhance antibacterial and cytotoxic properties. Materials and methods: Coatings were deposited on 316L SS substrates via 10 min of electrophoretic deposition at 10 V. Three coating formulations (0.5% ε-PLL, 0.5% ε-PLL / 0.02% GO composite and 0.5% ε-PLL / 0.02% GO / 0.001% Ag NP composite) were prepared. The coated samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field- emission scanning electron microscope, and energy dispersive x -ray spectroscopy. The antibacterial efficacy against Streptococcus mutans and Aggregatibacter actinomycetem comitans, as well as cytotoxicity were evaluated. Results: Characterisation confirmed the successful deposition of all coating formulations. The ε-PLL - GO/Ag NP composite coatings demonstrated the most potent antibacterial effects, with inhibition zones of 27 and 24 mm, respectively, followed by the ε-PLL--GO composite (25 and 22 mm) and ε-PLL (22 and 20 mm) against S. mutans and A. actinomycetem comitans respectively. All the coated samples exhibited a survival rate over 90% after 72 h with no cytotoxic effects observed. Conclusion: All the coated samples, especially the ε-PLL- GO /Ag NP composite, demonstrated promising biomedical characteristics, indicating potential for use in coatings for medical and dental equipment.