Green Synthesized Silver Nanoparticles: Genotoxic/Epigenetic Alterations in Human Peripheral Lymphocytes and Cytotoxicity in Human Colon Cell Lines.

Green synthesis offers an environmentally friendly alternative to conventional nanoparticle production, minimizing toxic reagents and waste generation. In this study, silver nanoparticles (AgNPs-KC27L) were synthesized using postbiotics derived from the Ligilactobacillus salivarius KC27L strain, representing a novel biosafe approach. The genotoxic potential of AgNPs-KC27L was assessed using chromosomal aberration (CA), cytokinesis block micronucleus cytome (CBMN-Cyt), and comet assays. No significant chromosomal changes were observed at 24 h; however, a significant increase in CA frequency was detected at 50 μg/mL after 48 h. MN assay results showed no significant alterations, whereas the comet assay revealed DNA damage at 25 and 50 μg/mL, indicated by increased tail length, intensity, and moment. Cytotoxicity analysis demonstrated reduced cell viability at higher concentrations (100-200 μg/mL), with IC₅₀ values ranging from 87 to 171 μg/mL, depending on the cell line (CCD-18Co, DLD-1, and HT-29) and exposure duration. Epigenetic effects were evaluated via qRT-PCR quantification of DNMT1, HDAC1, and HDAC3 expression, revealing a concentration-dependent biphasic response: Gene expression increased at lower concentrations but declined at higher doses. Overall, AgNPs-KC27L exhibited minimal genotoxic and cytotoxic effects at low concentrations, whereas higher concentrations induced both DNA and epigenetic alterations, highlighting their dual potential as biocompatible agents at low doses and biologically active at higher doses.