New insights into the size-independent bioactive potential of pristine and UV-B aged polyethylene microplastics

Stefanos Dailianis; Maria Rouni; Nina Maria Ainali; Dimitris Vlastos; George Z Kyzas; Dimitra A Lambropoulou; Dimitrios N Bikiaris

doi:10.1016/j.scitotenv.2024.170616

New insights into the size-independent bioactive potential of pristine and UV-B aged polyethylene microplastics

Sci Total Environ. 2024 Mar 25:918:170616. doi: 10.1016/j.scitotenv.2024.170616. Epub 2024 Feb 3.

Authors

Stefanos Dailianis¹, Maria Rouni², Nina Maria Ainali³, Dimitris Vlastos², George Z Kyzas⁴, Dimitra A Lambropoulou³, Dimitrios N Bikiaris⁵

Affiliations

¹ Department of Biology, School of Natural Sciences, University of Patras, GR-26500, Rio, Patras, Greece. Electronic address: sdailianis@upatras.gr.
² Department of Biology, School of Natural Sciences, University of Patras, GR-26500, Rio, Patras, Greece.
³ Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece.
⁴ Department of Chemistry, International Hellenic University, GR-65404 Kavala, Greece.
⁵ Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece.

PMID: 38311086
DOI: 10.1016/j.scitotenv.2024.170616

Abstract

The present study investigates the morphological, physicochemical, and structural changes occurred by the UV-B aging process of low-density polyethylene microplastics (LDPE MPs), as well as the bioactive potential of both pristine and UV_aged MPs towards healthy peripheral blood lymphocytes. Specifically, LDPE MPs (100-180 μm) prepared by mechanical milling of LDPE pellets, were UV-B irradiated for 120 days (wavelength 280 nm; temperature 25 °C; relative humidity 50 %) and further examined for alterations in their particle size and surface, their functional groups, thermal stability, and crystallinity (by means of SEM, FTIR spectroscopy, XRD patterns, and TGA measurements, respectively). In parallel, isolated human peripheral blood lymphocytes were treated with different concentrations (25-500 μg mL^-1) of either pristine or aged MPs (UV_free and UV_120d LDPE MPs) for assessing the cytogenotoxic (by means of trypan blue exclusion test and the cytokinesis-block micronucleus assay using cytochalasin-B) and oxidative effects (using the DCFH-DA staining) in both cases. According to the results, UV_free and UV_120d-LDPE MPs, with a size ranging from 100 to 180 μm, can differentially promote cytogenotoxic and oxidative alterations in human lymphocytes. In fact, UV_free LDPE MPs not being able to be internalized by cells due to their size, could indirectly promote the onset of mild oxidative and cytogenotoxic damage in human peripheral lymphocytes, via a dose-dependent but size-independent manner. The latter is more profound in case of the irregular-shaped UV_120d-LDPE MPs, bearing improved dispersibility and sharp edges (by means of cracks and holes), as well as oxygen-containing and carbonyl groups. To our knowledge, the present findings provide new data regarding the bioactive behavior of pristine and UV-B aged LDPE MPs, at least in the in vitro biological model tested, thus giving new evidence for their size-independent and/or indirect mode of action.

Keywords: Cytotoxicity; Genotoxicity; Low-density polyethylene; Lymphocytes; Microplastics; Photodegradation.

MeSH terms

Aged
Humans
Microplastics*
Particle Size
Plastics
Polyethylene / chemistry
Polyethylene / toxicity
Spectroscopy, Fourier Transform Infrared
Water Pollutants, Chemical* / toxicity

Substances

Microplastics
Polyethylene
Plastics
Water Pollutants, Chemical