Review of ecotoxicological studies of widely used polystyrene nanoparticles

Cationic Polystyrene Latex Nanocarriers for Immunostimulatory Long Double-Stranded RNA Delivery to Ovarian Cancer Cells

Long double-stranded (ds)RNA, a potent stimulator of type I interferon and the innate immune response. In the present study, we demonstrated, for the first time, the efficacy of cationic polystyrene latex nanostructures (clNPs) as a dsRNA carrier, improving cellular delivery and robustly potentiating the immunostimulatory capacity of dsRNA in the ovarian cancer cell line SKOV3. The clNPs complexed with an in vitro transcribed dsRNA molecule, were bound by SKOV3 cells, and had increased cellular association compared to uncomplexed clNPs. clNPs complexed with dsRNA induced a more robust innate immune response compared to dsRNA alone. Transcript expression of two interferon-stimulated genes, were increased 47- and 108-fold over dsRNA and induced a significant antiviral state against vesicular-stomatitis virus, resulting in a 3.3-fold improvement on the efficacy of dsRNA. These data highlight the potential of polystyrene latex nanostructures as dsRNA carriers for anticancer immunotherapies, improving the uptake and efficacy of the nucleic acid.

Interactions of alumina and polystyrene nanoparticles with the innate immune system of Galleria mellonella

Nowadays, particularly metallic, and polymeric nanoparticles (NPs) are widely produced and used in many fields. Due to the increase in both their usage and diversity, their release and accumulation in the environment are also accelerating. Therefore, their interactions with cells, especially immune cells, and their health risks are not fully understood. The impacts of metallic alumina (Al) NPs and polystyrene (PS) NPs obtained after the polymerization of carcinogenic styrene on living organisms have not yet been elucidated. Galleria mellonella larvae can biodegrade plastics. While biodegradation and solving the waste problem have attracted much attention, the interactions of this distinctive property of G. mellonella larvae in the immune system and ecosystem are not yet completely understood. Al and PS NPs were applied to G. mellonella separately. Al NPs were purchased and PS NPs were prepared from PS by single-emulsion technique and characterized. Then LC50 values of these NPs on G. mellonella were determined. The interactions of these NPs with encapsulation, melanization, and phenoloxidase activity, which express innate immune responses in G. mellonella larvae, were revealed. NP exposure resulted in suppression of the immune response, probably because it affects the functions of hemocytes such as enzymatic activation, hemocyte division, and populations. In this context, our data suggest that Al and PS NPs induce toxic impacts and negatively alter the physiological status of G. mellonella. It is also shown that G. mellonella has the potential to be an impactful alternative model for biosafety and nanotoxicology studies.

Ecotoxicological studies of direct and indirect genotoxicity with Artemia: a integrative review

Artemia is a brine shrimp genus adapted to extreme habitats like ranges salinity from 5-25 g/L and in temperatures from 9 to 35 °C. It is widely distributed and used as an environmental quality biomarker. Artemia franciscana and Artemia salina species are commonly used in ecotoxicological studies and genotoxicity assays due to their short life cycle, high fecundity rate, easy culture, and availability. Thus, considering the importance of these tests in ecotoxicological studies, the present study aimed to present Artemia genus as a biological model in genotoxicity research. To this end, we reviewed the literature, analyzing data published until July 2023 in the Web of Science, SCOPUS, Embase, and PubMed databases. After screening, we selected 34 studies in which the genotoxicity of Artemia for various substances. This review presents the variability of the experimental planning of assays and biomarkers in genotoxicity using Artemia genus as a biological model for ecotoxicological studies and show the possibility of monitoring biochemical alterations and genetic damage effects. Also highlight innovative technologies such as transcriptomic and metabolomic analysis, as well as studies over successive generations to identify changes in DNA and consequently in gene expression.

Plastic Fly: What Drosophila melanogaster Can Tell Us about the Biological Effects and the Carcinogenic Potential of Nanopolystyrene

Today, plastic pollution is one of the biggest threats to the environment and public health. In the tissues of exposed species, micro- and nano-fragments accumulate, leading to genotoxicity, altered metabolism, and decreased lifespan. A model to investigate the genotoxic and tumor-promoting potential of nanoplastics (NPs) is Drosophila melanogaster. Here we tested polystyrene, which is commonly used in food packaging, is not well recycled, and makes up at least 30% of landfills. In order to investigate the biological effects and carcinogenic potential of 100 µm polystyrene nanoparticles (PSNPs), we raised Oregon [R] wild-type flies on contaminated food. After prolonged exposure, fluorescent PSNPs accumulated in the gut and fat bodies. Furthermore, PSNP-fed flies showed considerable alterations in weight, developmental time, and lifespan, as well as a compromised ability to recover from starvation. Additionally, we noticed a decrease in motor activity in DNAlig4 mutants fed with PSNPs, which are known to be susceptible to dietary stressors. A qPCR molecular investigation of the larval intestines revealed a markedly elevated expression of the genes drice and p53, suggesting a response to cell damage. Lastly, we used warts-defective mutants to assess the carcinogenic potential of PSNPs and discovered that exposed flies had more aberrant masses than untreated ones. In summary, our findings support the notion that ingested nanopolystyrene triggers metabolic and genetic modifications in the exposed organisms, eventually delaying development and accelerating death and disease.

Miniaturizing Nanotoxicity Assays in Daphnids

The rapid progress of the modern world has resulted in new materials and products created at an accelerating pace. As such, nanoparticles have widespread applications and often find their way into the aquatic ecosystem. In the case of freshwater ecosystems, one of the commonly used bioindicators species used for pollution assessment is Daphnid magna. The Organization for Economic Co-operation and Development (OECD), and other organizations such as the European Chemicals Agency (ECHA) and Environmental Protection Agency (EPA), have set guidelines for acute toxicity testing in daphnids that are severely lacking in terms of information on the characteristics of the exposure vessel when studying the adverse effects of nanoparticles (NPs). Understanding the toxicity mechanisms of nanomaterials is imperative given the scarcity of information on their adverse effects. Furthermore, miniaturization of nanotoxicity assays can reduce the number of daphnids used, as well as the cost and nanomaterial waste, and provide results even at the individual animal level with enhanced reproducibility of testing. In this study, the impact of the exposure vessel on the observed physiological changes of daphnids was investigated for a silver nano ink. Exposures in eleven commercially available vessels; nine made of plastic and two made of glass were compared for 24 h. The effect of surface to volume ratio of the exposure vessel and the animal number or "crowding" during exposure was investigated in the context of miniaturizing biomarker assays as alternatives to traditional experimental setups in Daphnid magna. Toxicity curves showed differences depending on the vessel used, while a novel feeding rate assay and the activity of key enzymes were assessed as physiology endpoints.

Do nanoplastics impact Pb up-taking by Hordeum vulgare L.?

Most studies on nanoplastics (NPs) focus on aquatic environments, overlooking their combined bioaccumulation with pollutants in terrestrial ecosystems. This study addresses a part of this gap by investigating how polystyrene nanoplastics (PS-NPs) affect the bioaccumulation and translocation of lead (Pb) in Hordeum vulgare L. plants. Using the RHIZOtest device for precise soil contamination control, we quantified PS-NPs (50 nm) in plant shoots via pyrolysis-gas chromatography/mass spectrometry (Py-GCMS) after plant KOH digestion. Our findings revealed that PS-NPs reduce Pb bioaccumulation and make adsorbed Pb onto PS-NPs less bioavailable to plants. For the highest Pb concentration, the Pb uptake index (PUI) followed the trend: Free Pb > NPs + Pb > Pb primary adsorbed by NPs, showing reduced Pb translocation to shoots in the presence of PS-NPs. Moreover, the presence of Pb decreased the bioavailability of PS-NPs probably in response to PS-NPs aggregation or modified charge. The PS-NPs concentrations in shoots range from 275.2 to 400 μg g-1, representing 3.9 to 5.75% of the total PS-NPs. This study highlights the intricate interactions between nanoplastics and metals in soil-plant systems and emphasizes the need for further research on their combined effects and potential risks to food safety.

Volatile carbonyl metabolites analysis of nanoparticle exposed lung cells in an organ-on-a-chip system

The evaluation of nanoparticles (NPs) cytotoxicity is crucial for advancing nanotechnology and assessing environmental pollution. However, existing methods for NPs cytotoxicity evaluation suffer from limited accuracy and inadequate information content. In the study, we developed a novel detection platform that enables the identification of cellular carbonyl metabolites at the organ level. The platform is integrated with a cell co-culture lung organ chip (LOC) and a micropillar concentrator. Notably, our work represents the successful measurement of the amounts of cellular metabolites on LOC system. The volatile carbonyl metabolites (VCMs) generated by cells exposure to various types of NPs with different concentrations were captured and detected by high-resolution mass spectrometry (MS). Compared with conventional cell viability and reactive oxygen species (ROS) analysis, our method discerns the toxicological impact of NPs at low concentrations by analyzed VCM at levels as low as ppb level. The LOC system based metabolic gas detection confirmed that low concentrations of NPs have a toxic effect on the cell model, which was not reflected in the fluorescence detection, and the effect of NP material is more significant than the size effect. Furthermore, this method can distinguish different NPs acting on cell models through cluster analysis of multiple VCMs.

Microplastics and Oxidative Stress-Current Problems and Prospects

Microplastics (MPs) are plastic particles between 0.1 and 5000 µm in size that have attracted considerable attention from the scientific community and the general public, as they threaten the environment. Microplastics contribute to various harmful effects, including lipid peroxidation, DNA damage, activation of mitogen-activated protein kinase pathways, cell membrane breakages, mitochondrial dysfunction, lysosomal defects, inflammation, and apoptosis. They affect cells, tissues, organs, and overall health, potentially contributing to conditions like cancer and cardiovascular disease. They pose a significant danger due to their widespread occurrence in food. In recent years, information has emerged indicating that MPs can cause oxidative stress (OS), a known factor in accelerating the aging of organisms. This comprehensive evaluation exposed notable variability in the reported connection between MPs and OS. This work aims to provide a critical review of whether the harmfulness of plastic particles that constitute environmental contaminants may result from OS through a comprehensive analysis of recent research and existing scientific literature, as well as an assessment of the characteristics of MPs causing OS. Additionally, the article covers the analytical methodology used in this field. The conclusions of this review point to the necessity for further research into the effects of MPs on OS.

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.

Visual mapping of global nanoplastics research progresses and hotspots: a scientometric assessment analysis

Environmental plastic wastes are continuously degraded into microplastics (MPs) and nanoplastics (NPs); the latter are more potentially harmful to organisms and human health as their smaller size and higher surface-to-volume ratio. Previous reviews on NPs mainly concentrate on specific aspects, such as sources, environmental behavior, and toxicological effects, but few focused on NPs-related scientific publications from a global point of view. Therefore, this bibliometric study aims to summarize the research themes and trends on NPs and also propose potential directions for future inquiry. Related papers were downloaded from the Web of Science Core Collection database on NPs published from 2008 to 2021, and then retrieved information was analyzed using CiteSpace 6.1 R2 and VOSviewer (version 1.6.). Research on NPs mainly involved environmental behaviors, toxicological effects, identification and extraction of NPs, whereas aquatic environments, especially marine systems, attracted more attentions from these scientists compare to terrestrial environments. Furthermore, the adsorption behavior of pollutants by NPs and the toxicological effects of organisms exposed to NPs are the present hotspots, while the regulation of humic acid (HA) on NPs behaviors and the environmental behavior of NPs in freshwater, like rivers and lakes, are the frontier areas of research. This study also explored the possible opportunities and challenges that may be faced in NPs research, which provide a valuable summary and outlook for ongoing NPs-related research, which may be of intrigue and noteworthiness for relevant researchers.

Toxic effects of polystyrene nanoparticles on the development, escape locomotion, and lateral-line sensory function of zebrafish embryos

Environmental pollution by micro- and nanosized plastic particles is a potential threat to aquatic animals. Polystyrene is one of the most common plastic particles in aquatic environments. Previous studies found that polystyrene nanoparticles (PNs) can penetrate the integument and accumulate in the organs of fish embryos. However, the potential impacts of PNs on fish embryos are not fully understood. To investigate this issue, zebrafish embryos were exposed to different concentrations (10, 25, and 50 mg/L) of PNs (25 nm) for 96 h (4-100 h post-fertilization), and various endpoints were examined, including developmental morphology (body length, sizes of the eyes, otic vesicles, otoliths, pericardial cavity, and yolk sac), locomotion (touch-evoked escape response and spinal motor neurons), and lateral-line function (hair cell number and hair bundle number). Exposure to 50 mg/L of PNs resulted in significant adverse effects across all endpoints studied, indicating that embryonic development was severely disrupted, and both locomotion and sensory function were impaired. However, at 25 mg/L of PNs, only locomotion and sensory function were significantly affected. The effects were insignificant in all examined endpoints at 10 mg/L of PNs. Transcript levels of several marker genes for neuronal function and eye development were suppressed after treatment. Exposure to fluorescent PNs showed that they accumulated in various organs including, the eyes, gills, blood vessels, gallbladder, gut, and lateral line neuromasts. Overall, this study suggests that short-term exposure to a high concentration of PNs can threaten fish survival by impairing embryonic development, locomotion performance, and mechanical sensory function.

Role of Residual Monomers in the Manifestation of (Cyto)toxicity by Polystyrene Microplastic Model Particles

Polystyrene (PS) is an important model polymer for the investigation of effects of microplastic (MP) and nanoplastic (NP) particles on living systems. Aqueous dispersions of PS MP or NP contain residual monomers of styrene. In consequence, it is not clear if the effects observed in standard (cyto)toxicity studies are evoked by the polymer (MP/NP) particle or by residual monomers. We addressed that question by comparing standard PS model particle dispersions with in-house synthesized PS particle dispersions. We proposed a rapid purification method of PS particle dispersions by dialysis against mixed solvents and developed a simple method of UV-vis spectrometry to detect residual styrene in the dispersions. We found that standard PS model particle dispersions, which contain residual monomers, exerted a low but significant cytotoxicity on mammalian cells, while the in-house synthesized PS, after rigorous purification to reduce the styrene content, did not. However, the PS particles per se but not the residual styrene in both PS particle dispersions resulted in immobilization of Daphnia. Only by using freshly monomer-depleted particles, will it be possible in the future to assess the (cyto)toxicities of PS particles, avoiding an otherwise not controllable bias effect of the monomer.

Defining Quality Criteria for Nanoplastic Hazard Evaluation: The Case of Polystyrene Nanoplastics and Aquatic Invertebrate Daphnia spp

Polystyrene nanoparticles are the most investigated type of nanoplastics in environmental hazard studies. It remains unclear whether nanoplastic particles pose a hazard towards aquatic organisms. Thus, it was our aim to investigate whether the existing studies and data provided therein are reliable in terms of data completeness. We used the example of Daphnia spp. studies for the purpose of polystyrene nanoplastic (nanoPS) hazard evaluation. First, a set of quality criteria recently proposed for nanoplastic ecotoxicity studies was applied. These rather general criteria for all types of nanoplastics and different test organisms were then, in the second step, tailored and refined specifically for Daphnia spp. and nanoPS. Finally, a scoring system was established by setting mandatory (high importance) as well as desirable (medium importance) criteria and defining a threshold to pass the evaluation. Among the existing studies on nanoPS ecotoxicity for Daphnia spp. (n = 38), only 18% passed the evaluation for usability in hazard evaluation. The few studies that passed the evaluation did not allow for conclusions on the hazard potential of nanoPS because there was no consensus among the studies. The greatest challenge we identified is in data reporting, as only a few studies presented complete data for hazard evaluation.

Hazard of polystyrene micro-and nanospheres to selected aquatic and terrestrial organisms

Plastics contamination in the environment is a major concern. Risk assessment of micro- and nanoplastics (MPL and NPL) poses significant challenges due to MPL and NPL heterogeneity regarding compositional polymers, particle sizes and morphologies in the environment. Yet, there exists considerable toxicological literature on commercial polystyrene (PS) micro- and nanospheres. Although such particles do not directly represent the environmental MPL and NPL, their toxicity data should be used to advance the hazard assessment of plastics. Here, toxicity data of PS micro- and nanospheres for microorganisms, aquatic and terrestrial invertebrates, fish, and higher plants was collected and analyzed. The evaluation of 294 papers revealed that aquatic invertebrates were the most studied organisms, nanosized PS was studied more often than microsized PS, acute exposures prevailed over chronic exposures, the toxicity of PS suspension additives was rarely addressed, and ∼40 % of data indicated no organismal effects of PS. Toxicity mechanisms were mainly studied in fish and nematode Caenorhabditis elegans, providing guidance for relevant studies in higher organisms. Future studies should focus on environmentally relevant plastics concentrations, wide range of organisms, co-exposures with other pollutants, and method development for plastics identification and quantification to fill the gap of bioaccumulation assessment of plastics.