Distinct Bioactive Surface Coating Modulates Chronic Toxicity and Recovery Pathways in Silver-Nanoparticle-Exposed Cells

The use of silver nanoparticles (AgNPs) in biomedical and household products has rapidly increased in recent years. However, the long-term effects of these AgNPs on human health are poorly understood. In this study, AgNPs of approximately the same size were prepared with different surface functionalizations, namely, tyrosine (Tyr), curcumin (Cur), and epigallocatechin-3-gallate (EGCG). These were used to determine the acute and chronic toxicity on human cells, as well as the effects on oxidative stress, cell adhesion, and cell cycle progression. Additionally, we assessed cell recovery after 24 h of exposure and the effect of intermittent AgNP exposure on successive cell passages. The results indicate that Tyr-AgNPs showed negligible acute toxicity in cells but had the highest chronic toxicity profile. The cells took up to four passages to recover after 24 h of exposure to these NPs, most likely due to the generation of metal ions from the AgNPs. Meanwhile, Cur-AgNPs showed the lowest chronic toxicity. Since curcumin and EGCG molecules have more phenolic groups available than tyrosine, they provide better surface coverage of AgNPs, thereby reducing some of the toxic effects. Therefore, the findings from this study suggest that the bioactive surface coating on AgNPs plays a vital role in influencing their biocompatibility and might mitigate some of their long-term effects on human cells.