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13 pages, 2179 KiB

Open AccessArticle

Epigenetic and Gene Expression Responses of Daphnia magna to Polyethylene and Polystyrene Microplastics

by Hyungjoon Im, Jieun Lee, Jeong-Eun Oh, Jinyoung Song and Sanghyun Jeong

Molecules 2025, 30(7), 1608; https://doi.org/10.3390/molecules30071608 - 3 Apr 2025

Viewed by 568

Microplastics (MPs), ubiquitous environmental pollutants, pose substantial threats to aquatic ecosystems and organisms, including the model species Daphnia magna. This study examined the effects of polyethylene (PE) and polystyrene (PS) MPs on D. magna, focusing on their ingestion, epigenetic alterations, and [...] Read more.

Microplastics (MPs), ubiquitous environmental pollutants, pose substantial threats to aquatic ecosystems and organisms, including the model species Daphnia magna. This study examined the effects of polyethylene (PE) and polystyrene (PS) MPs on D. magna, focusing on their ingestion, epigenetic alterations, and transcriptional responses. Exposure experiments revealed a concentration-dependent accumulation of MPs, with PS particles showing higher ingestion rates due to their higher density and propensity for aggregation. Epigenetic analyses demonstrated that exposure to PE MPs significantly reduced the global DNA methylation (5-mC) of Daphnia magna, suggesting hypomethylation as a potential stress response. Conversely, the DNA hydroxymethylation (5-hmC) of Daphnia magna displayed variability under PS exposure. Transcriptional analysis identified a marked downregulation of Vitellogenin 1 (v1) and upregulation of Ecdysone Receptor B (ecr-b), highlighting the occurrence of stress-related and adaptive molecular responses. These findings enhance our understanding of the molecular and epigenetic effects of MPs on aquatic organisms, offering critical insights for the development of effective environmental management and conservation strategies in the face of escalating MP pollution. Full article

(This article belongs to the Special Issue Tracing the Fate of Microplastics from Daily Activities to Environments)

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12 pages, 1670 KiB

Open AccessArticle

A Simple Technique for Studying the Interaction of Polypropylene-Based Microplastics with Adherent Mammalian Cells Using a Holder

by Magdalena Obłoza, Magdalena Ścibor, Marta Kaczor-Kamińska and Kamil Kamiński

Molecules 2025, 30(3), 516; https://doi.org/10.3390/molecules30030516 - 23 Jan 2025

Viewed by 823

Abstract

Microplastics pose a great challenge to human health and could prove to be the most dangerous environmental contaminant of the 21st century. The study presented here is an attempt at proposing a new methodology for studying the interaction of microplastics with adherent mammalian [...] Read more.

Microplastics pose a great challenge to human health and could prove to be the most dangerous environmental contaminant of the 21st century. The study presented here is an attempt at proposing a new methodology for studying the interaction of microplastics with adherent mammalian cells using aides. The disposable holders proposed here provide direct contact between microplastics (with a density lower than that of water) and cells in the course of culturing, which is necessary as we postulate the existence of an interaction. Using several microscopic methods (confocal fluorescence microscopy and scanning electron microscopy (SEM)), we have observed that this interaction causes a non-destructive penetration of the cell monolayer and adhesion of microplastics to the cell surface. The Caco-2 cells were used for the experiments. The said cells are the approximation of the digestive system, which, due to the presence of plastics in drinking water, is particularly vulnerable to direct interactions with these contaminants. Model microplastics were obtained by grinding pellets of chemically pure polypropylene. The imaging of cells in both space and on the surface was supplemented by an assay to determine the cell welfare in the studied microplastic-exposed models, which did not show the occurrence of apoptosis or necrosis after a 24 h exposure. Full article

(This article belongs to the Special Issue Tracing the Fate of Microplastics from Daily Activities to Environments)

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11 pages, 20853 KiB

Open AccessArticle

Differences in Nanoplastic Formation Behavior Between High-Density Polyethylene and Low-Density Polyethylene

by Hisayuki Nakatani, Teruyuki Yamaguchi, Mika Asano, Suguru Motokucho, Anh Thi Ngoc Dao, Hee-Jin Kim, Mitsuharu Yagi and Yusaku Kyozuka

Molecules 2025, 30(2), 382; https://doi.org/10.3390/molecules30020382 - 17 Jan 2025

Viewed by 734

Abstract

High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE) films were used to create nanoplastic (NP) models, with the shape of delamination occurring during degradation. In the case of HDPE, selective degradation occurred not only in the amorphous part, but also in the crystalline part [...] Read more.

High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE) films were used to create nanoplastic (NP) models, with the shape of delamination occurring during degradation. In the case of HDPE, selective degradation occurred not only in the amorphous part, but also in the crystalline part at the same time. Some of the lamellae that extend radially to form the spherulite structure were missing during the 30-day degradation. The length of these defects was less than 1 µm. HDPE disintegrated within units of spherulite structure by conformational defects in lamellae, and the size of the fragments obtained had a wide distribution. LDPE was synthesized by radical polymerization, so it contained a cross-linked part. The part was not sufficiently fused, and when it degraded, it delaminated and separated preferentially. The zeta potential reached a minimum value of approximately −20 mV at the degradation time of 21 days, and then increased. This complex dependence on degradation time was due to NP particle aggregation. The addition of 1% Triton(R) X-114 surfactant was effective in stabilizing the NP dispersion. The particle size remained constant at around 20 nm for degradation times of 15–30 days. Full article

(This article belongs to the Special Issue Tracing the Fate of Microplastics from Daily Activities to Environments)

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10 pages, 646 KiB

Open AccessArticle

Determination of Tire Wear Particle-Type Polymers by Combination of Quantitative Nuclear Magnetic Resonance Spectroscopy and Soxhlet Extraction

by Marcel Günther, Gizem Kirimlioglu Sayilik and Wolfgang Imhof

Molecules 2024, 29(24), 5899; https://doi.org/10.3390/molecules29245899 - 13 Dec 2024

Cited by 1 | Viewed by 698

Abstract

Tire wear particles (TWPs) are among the most relevant sources of microplastic pollution of the environment. Nevertheless, common analytical methods like IR and Raman spectroscopy are highly impaired by additives and filler materials, leaving only thermogravimetric methods for chemical analysis of TWPs in [...] Read more.

Tire wear particles (TWPs) are among the most relevant sources of microplastic pollution of the environment. Nevertheless, common analytical methods like IR and Raman spectroscopy are highly impaired by additives and filler materials, leaving only thermogravimetric methods for chemical analysis of TWPs in most cases. We herein present quantitative NMR spectroscopy (qNMR) as an alternative tool for the quantification of the polymeric material used for the production of tires, including natural rubber (NR), styrene–butadiene–copolymer (SBR), polyethylene–co-propylene (EPR) and polybutadiene (BR). Limits of quantification (LOQ) between 3 µg and 43 µg per sample and recovery rates of 72–92% were achieved for all tested polymer types. The first results of combining these measurements with Soxhlet extraction as a sample preparation tool are presented alongside the qNMR experiments. Full article

(This article belongs to the Special Issue Tracing the Fate of Microplastics from Daily Activities to Environments)

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16 pages, 4844 KiB

Open AccessArticle

Effect of Copper Antifouling Paint on Marine Degradation of Polypropylene: Uneven Distribution of Microdebris between Nagasaki Port and Goto Island, Japan

by Hisayuki Nakatani, Kaito Yamashiro, Taishi Uchiyama, Suguru Motokucho, Anh Thi Ngoc Dao, Hee-Jin Kim, Mitsuharu Yagi and Yusaku Kyozuka

Molecules 2024, 29(5), 1173; https://doi.org/10.3390/molecules29051173 - 6 Mar 2024

Viewed by 1732

Abstract

Microplastics (MP) encompass not only plastic products but also paint particles. Marine microdebris, including MP, was retrieved from five sampling stations spanning Nagasaki-Goto island and was classified into six types, primarily consisting of MP (A), Si-based (B), and Cu-based (C) paint particles. Type-A [...] Read more.

Microplastics (MP) encompass not only plastic products but also paint particles. Marine microdebris, including MP, was retrieved from five sampling stations spanning Nagasaki-Goto island and was classified into six types, primarily consisting of MP (A), Si-based (B), and Cu-based (C) paint particles. Type-A particles, i.e., MP, were exceedingly small, with 74% of them having a long diameter of 25 µm or less. The vertical distribution of type C, containing cuprous oxide, exhibited no depth dependence, with its dominant size being less than 7 μm. It was considered that the presence of type C was associated with a natural phenomenon of MP loss. To clarify this, polypropylene (PP) samples containing cuprous oxide were prepared, and their accelerated degradation behavior was studied using a novel enhanced degradation method employing a sulfate ion radical as an initiator. Infrared spectroscopy revealed the formation of a copper soap compound in seawater. Scanning electron microscopy/energy-dispersive X-ray spectroscopy analysis indicated that the chemical reactions between Cl⁻ and cuprous oxide produced Cu⁺ ions. The acceleration of degradation induced by the copper soap formed was studied through the changes in the number of PP chain scissions, revealing that the presence of type-C accelerated MP degradation. Full article

(This article belongs to the Special Issue Tracing the Fate of Microplastics from Daily Activities to Environments)

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12 pages, 3931 KiB

Open AccessArticle

Study on the Thermal Stabilizing Process of Layered Double Hydroxides in PVC Resin

by Zhi Rao, Kaitao Li, Pingli Liu, Yanjun Lin and Xiang Lyu

Molecules 2023, 28(23), 7792; https://doi.org/10.3390/molecules28237792 - 27 Nov 2023

Cited by 1 | Viewed by 1789

Abstract

Poly(vinyl chloride) (PVC) is widely used in various fields and requires the use of thermal stabilizers to enhance its thermal stability during processing because of its poor thermal stability. Layered double hydroxides (LDHs) are widely considered to be one kind of highly efficient [...] Read more.

Poly(vinyl chloride) (PVC) is widely used in various fields and requires the use of thermal stabilizers to enhance its thermal stability during processing because of its poor thermal stability. Layered double hydroxides (LDHs) are widely considered to be one kind of highly efficient and environmentally friendly PVC thermal stabilizer. To investigate the thermal stabilizing process of layered double hydroxides (LDHs) in PVC resin, PVC and MgAl-LDHs powders with different interlayer anions (CO₃²⁻, Cl⁻, and NO₃⁻) were physically mixed and aged at 180 °C. The structure of LDHs at different aging times was studied using XRD, SEM, and FT-IR. The results show that the thermal stabilizing process of LDHs on PVC mainly has three stages. In the first stage, the layers of LDHs undergo a reaction with HCl, which is released during the thermal decomposition of PVC. Subsequently, the ion exchange process occurs between Cl⁻ and interlayer CO₃²⁻, resulting in the formation of MgAl-Cl-LDHs. Finally, the layers of MgAl-Cl-LDHs react with HCl slowly. During the thermal stabilizing process of MgAl-Cl-LDHs, the peak intensity of XRD reduces slightly, and no new XRD peak emerges. It indicates that only the first step happens for MgAl-Cl-LDHs. The TG-DTA analysis of LDHs indicates that the interaction of LDHs with different interlayer anions has the following order: NO₃⁻ < CO₃²⁻ < Cl⁻, according to the early coloring in the thermal aging test of PVC composites. The results of the thermal aging tests suggest that LDHs with a weak interaction between interlayer anions and layers can enhance the early stability of PVC significantly. Furthermore, the thermal aging test demonstrates that LDHs with high HCl absorption capacities exhibit superior long-term stabilizing effects on PVC resin. This finding provides a valuable hint for designing an LDHs/PVC resin with a novel structure and excellent thermal stability. Full article

(This article belongs to the Special Issue Tracing the Fate of Microplastics from Daily Activities to Environments)

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13 pages, 2640 KiB

Open AccessArticle

Microplastics’ Shape and Morphology Analysis in the Presence of Natural Organic Matter Using Flow Imaging Microscopy

by Soyoun Kim, Yejin Hyeon and Chanhyuk Park

Molecules 2023, 28(19), 6913; https://doi.org/10.3390/molecules28196913 - 3 Oct 2023

Cited by 5 | Viewed by 2531

Abstract

Ubiquitous microplastics in urban waters have raised substantial public concern due to their high chemical persistence, accumulative effects, and potential adverse effects on human health. Reliable and standardized methods are urgently needed for the identification and quantification of these emerging environmental pollutants in [...] Read more.

Ubiquitous microplastics in urban waters have raised substantial public concern due to their high chemical persistence, accumulative effects, and potential adverse effects on human health. Reliable and standardized methods are urgently needed for the identification and quantification of these emerging environmental pollutants in wastewater treatment plants (WWTPs). In this study, we introduce an innovative rapid approach that employs flow imaging microscopy (FlowCam) to simultaneously identify and quantify microplastics by capturing high-resolution digital images. Real-time image acquisition is followed by semi-automated classification using customized libraries for distinct polyethylene (PE) and polystyrene (PS) microplastics. Subsequently, these images are subjected to further analysis to extract precise morphological details of microplastics, providing insights into their behavior during transport and retention within WWTPs. Of particular significance, a systematic investigation was conducted to explore how the presence of natural organic matter (NOM) in WWTPs affects the accuracy of the FlowCam’s measurement outputs for microplastics. It was observed that varying concentrations of NOM induced a more curled shape in microplastics, indicating the necessity of employing pre-treatment procedures to ensure accurate microplastic identification when utilizing the FlowCam. These observations offer valuable new perspectives and potential solutions for designing appropriate treatment technologies for removing microplastics within WWTPs. Full article

(This article belongs to the Special Issue Tracing the Fate of Microplastics from Daily Activities to Environments)

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14 pages, 5053 KiB

Open AccessArticle

Complementary Analysis for Undetectable Microplastics from Contact Lenses to Aquatic Environments via Fourier Transform Infrared Spectroscopy

by Jieun Lee, Yejin Lee, Jeonghyeon Lee, Minseong Kang and Sanghyun Jeong

Molecules 2023, 28(9), 3713; https://doi.org/10.3390/molecules28093713 - 25 Apr 2023

Cited by 8 | Viewed by 2598

Abstract

Although microplastics (MPs) are intrinsically toxic and function as vectors for organic micropollutants, their discharge from wastewater treatment plant effluents and human activity remains unknown owing to the limitations of detection and treatment technologies. It is imperative to quantify MPs from human activities [...] Read more.

Although microplastics (MPs) are intrinsically toxic and function as vectors for organic micropollutants, their discharge from wastewater treatment plant effluents and human activity remains unknown owing to the limitations of detection and treatment technologies. It is imperative to quantify MPs from human activities involving the consumption of various plastic products. This study warns that contact lenses can generate MPs and nanoplastics (NPs) after being discharged into aquatic environments. Identification via micro-Fourier transform infrared spectroscopy revealed that the fragmented particles (from a few tens to a few hundred micrometres) could not be detected as poly(2-hydroxyl methacrylate), the component of contact lenses, owing to changes in its chemical properties. After the degradation process, the median size of the contact lens particles decreased from 313 to 85 µm. Approximately 300,600 g of contact lens waste is discharged into sewage systems daily in the United States of America (USA), where 45 million people wear contact lenses and throw away one-fifth of them every day. Contact lens waste (1 g) has the potential to release 5653.3–17,773.3 particles of MPs. This implies that the currently reported MP amounts in the environmental matrix exclude significant amounts of MPs and NPs from discharged contact lenses. The identification method should be examined, and a registration of the disposal process should be established. Full article

(This article belongs to the Special Issue Tracing the Fate of Microplastics from Daily Activities to Environments)

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