Prospects on the nano-plastic particles internalization and induction of cellular response in human keratinocytes

Abstract Background Today, cosmetic usage has become customary in both men and women towards improving their appearance and increase societal visibility. In this study, the nano-sized (30 to 300 nm) plastic particles were isolated from the commercial face-scrubs and treated on the human keratinocytes. Results The adherence studies of polyethylene nano-plastics (PENPs), polystyrene NPs (PSNPs), and face-scrubs isolated nano-plastics (NPs) on the keratin layer revealed a rapid attachment of NPs on the skin from the cosmetics that have short exposure time. This attachment property could facilitate further adherence of protein molecules on NPs and the protein-corona formation. The protein-corona mimics protein aggregates, thereby triggers the macropinocytosis followed by the macropinolysosomal process in the cell. Then the internalized NPs induced the concentration-dependent cytotoxic, cytostatic and cytoprotective activity in keratinocytes. Both single dose and chronic long-term exposure of lethal and sub-lethal concentrations of NPs resulted in the oxidative stress-mediated down-regulation of cell growth and proliferation inhibition. Autophagy and premature aging were also observed in the NPs internalized HaCaT cells incubated in a fresh, NPs-free medium. Conclusion At the outset, this work provides insight into the NPs concentration-dependent regulatory, cytoprotective, and cytotoxic effects in HaCaT cells. Further studies are required to identify the detailed mechanisms of NPs toxicity and cytoprotective events in cells at the molecular level.