Polycarbonate nanoplastics and the in vitro assessment of their toxicological impact on liver functionality

Abstract

Herein, we demonstrate the formation of polycarbonate (PC) nanoplastics (NPs) through laser ablation of solid PC films in water. We prove that the size of the produced particles depends directly on the laser energy fluence, ranging between a few tens and a few hundreds of nanometers. Focusing on NPs of the smallest size range, the chemical characterization proves that they are composed of PC, while their surface is highly oxidized, similar to the PC fragments derived from natural photo-degradation processes. Together with the PC-NPs, additional photo-degradation by-products are formed, similar to the ones expected from environmentally exposed plastics. With the aim of providing reliable insights into the potentially detrimental effects of PC-based plastic litter on human health, upcyte® human hepatocytes were selected as a hepatic cellular model for assessing the hepatotoxicity of PC-NPs. Although no cytotoxic effects were observed at low concentrations (up to 40 μg mL⁻¹), an alteration of the cytochrome P450 system (CYP3A4, CYP2C9, and CYP1A2) and a reduction of the albumin production were found. Interestingly, we prove that these cytotoxic effects can be attributed to both the nano-particulate matter (i.e., the NPs) and the molecular matter (i.e., the photo-degradation by-products). Although far from the recapitulation of the real fate of NPs in the environment, with this novel approach we demonstrate the possibility of obtaining in a single step an environmentally pertinent composition of PC photo-degradation products, applied on a physiologically meaningful hepatic cellular model for human exposure studies.