Evaluation of In Vitro Genotoxicity of Polystyrene Nanoparticles in Human Peripheral Blood Mononuclear Cells

Polyethylene Terephthalate Microplastics Generated from Disposable Water Bottles Induce Interferon Signaling Pathways in Mouse Lung Epithelial Cells

Microplastics (MPs) are present in ambient air in a respirable size fraction; however, their potential impact on human health via inhalation routes is not well documented. In the present study, methods for a lab-scale generation of MPs from regularly used and littered plastic articles were optimized. The toxicity of 11 different types of MPs, both commercially purchased and in-lab prepared MPs, was investigated in lung epithelial cells using cell viability, immune and inflammatory response, and genotoxicity endpoints. The underlying mechanisms were identified by microarray analysis. Although laborious, the laboratory-scale methods generated a sufficient quantity of well characterized MPs for toxicity testing. Of the 11 MPs tested, the small sized polyethylene terephthalate (PETE) MPs prepared from disposable water bottles induced the maximum toxicity. Specifically, the smaller size PETE MPs induced a robust activation of the interferon signaling pathway, implying that PETE MPs are perceived by cells by similar mechanisms as those employed to recognize pathogens. The PETE MPs of heterogenous size and shapes induced cell injury, triggering cell death, inflammatory cascade, and DNA damage, hallmark in vitro events indicative of potential in vivo tissue injury. The study establishes toxicity of specific types of plastic materials in micron and nano size.

In Vitro Evaluation of DNA Damage Induction by Silver (Ag), Gold (Au), Silica (SiO2), and Aluminum Oxide (Al2O3) Nanoparticles in Human Peripheral Blood Mononuclear Cells

Nanoparticles (NPs) are increasingly applied in a wide range of technological and medical applications. While their use offers numerous benefits, it also raises concerns regarding their safety. Therefore, understanding their cytotoxic effects and DNA-damaging properties is crucial for ensuring the safe application of NPs. In this study, DNA-damaging properties of PVP-coated silver, silica, aluminum oxide (13 nm and 50 nm), and gold (5 nm and 40 nm) NPs in human peripheral blood mononuclear cells (PBMCs) were investigated. NPs' internalization and induction of reactive oxygen species were evaluated using flow cytometry. Cytotoxic properties were determined using a dual acridine orange/ethidium bromide staining technique while DNA-damaging properties were assessed using an alkaline comet assay. We observed that Ag, SiO2, and both sizes of Al2O3 NPs were efficiently internalized by human PBMCs, but only PVP-AgNPs (at 10-30 µg/mL) and SiO2 NPs (at concentrations > 100 µg/mL) induced significant DNA damage after a 24 h exposure. In contrast, the uptake of both sizes of gold nanoparticles was limited, though they were able to cause significant DNA damage after a 3 h exposure. These findings highlight the different responses of human PBMCs to various NPs, emphasizing the importance of their size, composition, and internalization rates in nanotoxicology testing.

Characterization of Nanoprecipitated PET Nanoplastics by 1H NMR and Impact of Residual Ionic Surfactant on Viability of Human Primary Mononuclear Cells and Hemolysis of Erythrocytes

Manufactured nanoplastic particles (NPs) are indispensable for in vitro and in vivo testing and a health risk assessment of this emerging environmental contaminant is needed. The high surface area and inherent hydrophobicity of plastic materials makes the production of NPs devoid of any contaminants very challenging. In this study, we produced nanoprecipitated polyethylene terephthalate (PET) NPs (300 nm hydrodynamic diameter) with an overall yield of 0.76%. The presence of the ionic surfactant sodium dodecyl sulfate (SDS) was characterized by 1H NMR, where the relative ratio of NP/surfactant was monitored on the basis of the chemical shifts characteristic of PET and SDS. For a wide range of surfactant/NP ratios (17:100 to 1.2:100), the measured zeta potential changed from -42.10 to -34.93 mV, but with an NP concentration up to 100 μg/mL, no clear differences were observed in the cellular assays performed in protein-rich media on primary human cells. The remaining impurities contributed to the outcome of the biological assays applied in protein-free buffers, such as human red blood cell hemolysis. The presence of SDS increased the NP-induced hemolysis by 1.5% in protein-rich buffer and by 7.5% in protein-free buffer. As the size, shape, zeta potential, and contaminants of NPs may all be relevant parameters for the biological effects of NPs, the relative quantification of impurities exemplified in our work by the application of 1H NMR for PET NPs and the ionic surfactant SDS could be a valuable auxiliary method in the quality control of manufactured NPs.