Plastic particle pollution has been shown to be almost completely ubiquitous within our surrounding environment. This ubiquity in combination with a variety of unique properties (e.g. density, hydrophobicity, surface functionalization, particle shape and size, transition temperatures, and mechanical properties) and the ever-increasing levels of plastic production and use has begun to garner heightened levels of interest within the scientific community. However, as a result of these properties, plastic particles are often reported to be challenging to study in complex (i.e. real) environments. Therefore, this review aims to summarize research generated on multiple facets of the micro- and nanoplastics field; ranging from size and shape definitions to detection and characterization techniques to generating reference particles; in order to provide a more complete understanding of the current strategies for the analysis of plastic particles. This information is then used to provide generalized recommendations for researchers to consider as they attempt to study plastics in analytically complex environments; including method validation using reference particles obtained via the presented creation methods, encouraging efforts towards method standardization through the reporting of all technical details utilized in a study, and providing analytical pathway recommendations depending upon the exact knowledge desired and samples being studied.

Small plastic particles such as micro- (<5 mm), sub-micro- (1 µm–100 nm) and nanoplastics (<100 nm) are known to be ubiquitous within our surrounding environment. However, to date relatively few methods exist for the reliable detection of nanoplastic particles in relevant sample matrices such as foods or environmental samples. This lack of relevant data is likely a result of key limitations (e.g., resolution and/or scattering efficiency) for common analytical techniques such as Fourier transform infrared or Raman spectroscopy. This study aims to address this knowledge gap in the field through the creation of surface-enhanced Raman scattering spectroscopy substrates utilizing spherical gold nanoparticles with 14 nm and 46 nm diameters to improve the scattering signal obtained during Raman spectroscopy measurements. The substrates are then used to analyze polystyrene particles with sizes of 161 nm or 33 nm and poly(ethylene terephthalate) particles with an average size of 62 nm. Through this technique, plastic particles could be detected at concentrations as low as 10 µg/mL, and analytical enhancement factors of up to 446 were achieved.

As the prevalence of plastic micro- and nanoparticles in the environment, foods, and beverages continues to increase, the risk of human exposure to and uptake of such particles, notably via ingestion or inhalation, is also elevated. Despite this development, relatively little is known about the potential adverse effects of plastic particles on humans. The lack of relevant plastic nanoparticles for use in studies investigating their behavior and effect on human cells is a key hurdle that must be overcome prior to generating hazard data. We herein demonstrate the creation of fluorescent nanoparticles of the thermoplastic polymers poly(ethylene terephthalate), polypropylene, and polystyrene. The particles were produced by melt-processing and milling. The analysis of scanning electron microscopy images showed core diameters of less than 75 nm. Furthermore, the images revealed that the milled particles had highly heterogeneous shapes, as is often seen in environmental samples. The particles were exposed to relevant cell lines (i.e. Caco-2 intestinal epithelial cells and J774A.1 macrophages) to determine their uptake, assessed by confocal laser microscopy, and biocompatibility, assessed by measuring the release of lactate dehydrogenase. Exposure data showed no cytotoxicity at the concentrations utilized in this study. Interaction of the particles was found to be cell type dependent, with agglomeration on the apical surface and few intracellular particles in the intestinal epithelial cells in comparison to numerous internalized particles in the macrophages. In conclusion, the herein presented melt-processing and milling methods resulted in heterogeneously shaped plastic nanoparticles with a fluorescence label allowing their behavior within a complex biological environment to be studied.

This study focuses on using gold nanostar-based SERS substrates to detect 4 different types of plastic (6 particle sizes within the submicron- and nano-regimes). Substrates could be used to detect concentrations of plastics as low as 625 ng mL⁻¹.

Areas like the Mediterranean coastlines, which have high population density, represent locations of high pollution risk for surrounding environments. Thus, this study aims to compare data on the abundance, size, and composition of buoyant plastic particles collected during two weeks in 2019 in the Ligurian and Tyrrhenian Seas with data from 2018. The results from 2019 show average meso- and microplastic particle concentrations of 255,865 ± 841,221 particles km^-2, or 394.19 ± 760.87 g km^-2; values which differ significantly from those reported in 2018. Microplastic particles accounted for 88.7% of the sample; the majority of which had a size range being between 1 and 2.5 mm. These data are an important milestone for long-term monitoring of the highly variable plastic pollution levels within this region; showing overlaps in zones of pollutant accumulation in addition to increased overall concentrations of plastic particles compared to previous data.