(143e) Silver Nanoparticle Surface Chemistry Affects Protein Interactions, Cell Viability, and Gene Expression in Human Liver Cells

Silver nanoparticles (AgNPs) are increasingly being used in consumer and biomedical applications for their antimicrobial and plasmonic properties. Yet, detailed characterizations of physiological responses to AgNPs, as well as the influence of particle properties (such as surface chemistry) and interactions with other biomolecules on these responses are needed before their wide application. Furthermore, increasing concerns of frequent and cumulative exposures point to a need for cumulative risk assessment studies of AgNP exposure. Our work uses AgNPs with a range of surface coatings to evaluate the role of surface charge in protein interactions, cellular cytotoxicity, and gene expression. Conformational changes in the model protein human serum albumin (HSA) upon AgNP interaction, as monitored via circular dichroism spectroscopy, were most pronounced for cationic particles. In contrast, HSA-AgNP binding constants were highest for negatively charged AgNPs, though the differences in affinities were not significant across different surface coatings. Consistent with the trends in HSA-AgNP binding affinities, HSA-mediated changes in AgNP hydrodynamic radius and oxidative dissolution were highest for anionic particles. Cytotoxicity experiments carried out using hepatic cells revealed that none of the AgNP preparations studied showed significant toxicity at low nanoparticle concentrations. At higher concentrations, however, cationic AgNPs showed significant impacts on cell viability, both with and without HSA coating. Consistent with the cytotoxicity studies, results of transcriptomics analysis demonstrated that AgNPs altered gene transcription of HepG2 cells in a time-dependent manner, with the most dramatic effects seen for cationic AgNPs. Furthermore, universal to all surface-coatings, AgNPs treated cells responded by inactivating proliferation and enabling cell cycle checkpoints. Taken together, these results demonstrated the significance of AgNP surface charge in both biophysical HSA-AgNP interactions and cytotoxicity and gene expression, with cationic AgNP causing greatest disruption to HSA structure and cell responses.