Skip to main content
NCBI home page
Environment & Health logoLink to Environment & Health
. 2026 Jan 23;4(6):1139–1150. doi: 10.1021/envhealth.5c00633

Carboxyl Surface Modification Attenuates Polystyrene- but Not Poly(methyl methacrylate) Nanoplastic-Induced Gut Dysbiosis in Zebrafish Larvae

Eunbi Kwak †, Shiqi Gai †, Xueran Xu †, Wen Xu †, Guotao Peng †,*
PMCID: PMC13288231  PMID: 42344600

Abstract

Plastic polymers are widely recognized as significant environmental toxicants through their generation of nanoplastics (NPs), with polystyrene (PS) and poly­(methyl methacrylate) (PMMA) among the most frequently detected in ecosystems. While carboxyl surface modification is known to reduce NP toxicity in some systems, its protective efficacy in intestinal environments remains unclear. This study investigated the comparative effects of pristine PS and PMMA versus their carboxylated derivatives (PS-COOH and PMMA-COOH) on gut dysbiosis in zebrafish larvae. Pathological examination revealed that PS induced the most severe intestinal epithelial damage, which was effectively mitigated by carboxylation. Conversely, PMMA triggered robust gut inflammation, evidenced by significant upregulation of proinflammatory markers IL-1β and NOS2A, effects that persisted despite carboxylation. These differences were correlated with microbiota shifts: PMMA groups significantly enriched opportunistic pathogens (Vibrio and Morganella), while PS-COOH only partially restored microbial balance. Functional analyses identified that carboxylation disrupts key microbial pathways, including amino acid metabolism and NOD-like receptor signaling, which are crucial for maintaining intestinal homeostasis. The roles of gut microbes were further verified by challenging the microbiota-depleted model with Morganella morganii. Our results demonstrate that polymer composition dictates carboxyl modification efficacyprotective for PS but ineffective for PMMAhighlighting the need for material-specific NP safety assessments.

Keywords: Carboxyl modification, Nanoplastics, Gut microbiota, Intestinal barrier, Microbe−host interactions

graphic file with name eh5c00633_0007.jpg

graphic file with name eh5c00633_0006.jpg

Introduction

Plastic polymers have become indispensable in modern applications due to their durability, versatility, and cost-effectiveness. However, their environmental persistence and degradation into micro- (MPs) and nanoplastics (NPs) raise significant global ecotoxicological concerns and health risks. − Among these, polystyrene (PS) is one of the most extensively utilized plastics, primarily for packaging and insulation, resulting in the common detection of PS NPs in environmental samples. While the toxic effects of PS NPs are well documented, poly­(methyl methacrylate) (PMMA) NPs have received less attention despite their frequent detection in environmental and human samples. − PMMA’s optical transparency and impact resistance have driven its adoption in diverse biomedical applications, particularly in joint replacement devices. − Recent evidence indicates expanding use of PMMA in dental applications, where grinding and polishing procedures generate substantial NP debris, raising new concerns regarding oral exposure routes alongside previously reported systemic effects. ,, While environmentally relevant concentrations of PS and PMMA NPs are reported to range from 0.01 to 10 mg/L, toxicological studies have used exposure concentrations ranging from μg/L to g/L to simulate environmental exposure and elicit observable toxic effects in zebrafish. − Moreover, a recent study has demonstrated that PMMA exposure perturbs the gut microbiome, compromises tight junction proteins, and modulates lipid metabolism via the gut–liver axis. Therefore, investigating the potential adverse effects of orally ingested PS- and PMMA-NPs is essential to fully characterize their biological outcomes and guide safety regulations.

While complete avoidance of plastic polymers is often impossible, their potential toxicity can be mitigated through surface physicochemical modifications. A common strategy involves functionalizing NP surfaces with specific functional groups to modulate surface charge and hydrophilicity. − These alterations critically influence the nanoparticle–biological system interface, leading to differential biological outcomes. ,, For instance, unmodified PMMA was shown to exert stronger toxic effects in the red microalgae Rhodomonas baltica than carboxyl-modified (−COOH) PMMA, an effect attributed to distinct interactions at the cell surface. Similarly, amine-functionalized (−NH2) PS MPs with positive charges were more readily absorbed by intestinal epithelial Caco-2 monolayers than their carboxylated counterparts with negative charges, resulting in greater cytotoxicity and more severe epithelial barrier disruption. The intestine represents the primary target for ingested NPs, comprising multiple interacting layers including gut microbiota, mucins, epithelial cells, and immune components that collectively maintain host defense. These intestinal barriers experience varying degrees of homeostatic disruption depending on the nature of stimuli. , Zebrafish serve as an ideal vertebrate model for studying aquatic toxicant effects due to their physiological relevance and conserved intestinal biology. − Our recent findings show that PS NPs and MPs induce distinct gut inflammatory responses in zebrafish larvae, tightly correlated with specific gut microbiota dysbiosis patterns. Although negatively charged carboxyl groups are generally believed to reduce nanoparticle toxicity by limiting cellular interactions, their intestinal protective efficacy remains unclear, particularly regarding: polymer-specific variability and functional consistency across the intestine’s multiple biological barriers.

This study evaluated the comparative effects of carboxyl-modified versus pristine PS and PMMA NPs on gut dysbiosis in zebrafish larvae. Following 48 h exposure to four NP types, we assessed histological and morphological alterations, inflammatory and tight-junction-related gene expression changes, and microbial community shifts. Correlation analyses revealed significant relationships among microbiota composition, histopathological markers, and gene expression profiles. Functional prediction analysis further identified key microbial metabolic pathways altered by carboxyl-modified NPs. The critical role of the gut microbiota in NP toxicity was further confirmed by a bacterial challenge with Morganella morganii in a microbiota-depleted model. Among the opportunistic taxa identified, Morganella morganii is a clinically relevant pathobiont whose expansion commonly reflects gut epithelial and microbial dysbiosis, making it a particularly informative genus for probing NP-driven intestinal perturbation. These findings provide insights into how both polymer type and surface carboxylation collectively influence NP interactions with the multilayered intestinal barrier system.

MATERIALS and METHODS

Physicochemical Characterization of Nanoplastic Particles

PS, PMMA, and their carboxyl-functionalized counterparts (PS-COOH and PMMA-COOH) with 100 nm nominal diameter were purchased from Huge Biotechnology (Shanghai, China). These particles were supplied as high-purity grade without any additives or stabilizers. Transmission electron microscopy (TEM) was used to analyze the size and morphology of the NPs. Fourier transform infrared (FTIR) analysis was performed to confirm characteristic functional groups through absorbance peaks at specific wavenumbers. The hydrodynamic size and zeta potential were characterized in zebrafish larva maintenance medium (E3) using a Zetasizer Nano instrument (ZS 90, Malvern Instruments Ltd., UK).

Nanoplastic Exposure in Zebrafish Larvae

Zebrafish larvae at 6 days postfertilization (dpf) were exposed to NPs at concentrations of 25, 50, 75, and 100 mg/L for 48 h. NP exposure was performed from 4 dpf to 6 dpf, a developmental window during which the zebrafish digestive tract, liver and hepato-pancreatic system are functionally established. The onset of exogenous feeding also occurs within this period. In order to minimize nutrient- and diet-related confounding effects on the intestinal physiology and microbiota composition, the NP exposure was completed prior to the first feeding. , The nonlethal dose (100 mg/L) was then selected for subsequent intestinal toxicity evaluations. While this concentration exceeds environmentally relevant levels, it aligns with concentrations used in previous long-term zebrafish exposure studies, where PS and PMMA NPs were tested at ranges from 1 μg/L to 75 mg/L. , This concentration enables consistent and robust detection of polymer-type- and surface-functionalization-dependent biological responses within a short exposure duration. A preliminary range-finding assay confirmed the absence of lethality and malformations at 100 mg/L, supporting its suitability for investigating sublethal gut dysbiosis. Specifically, 1 day prior to NP exposure, larvae in E3 medium were transferred to a 24-well plate with 10 larvae per well. Each exposure condition included four technical replicates (4 wells) and was repeated across three independent biological replicates (n = 3). After exposure, samples were preserved as follows: 4% paraformaldehyde for histology, 2.5% glutaraldehyde for TEM analysis, and liquid nitrogen for RT-qPCR and 16S rRNA gene sequencing. All procedures were performed in accordance with the Animal Ethics Committee at Tongji University (ethical permit no. TJAD00723B01).

Histopathology Analysis

Intestinal cross sections from zebrafish larvae were analyzed using hematoxylin and eosin (H&E) and Alcian Blue-Period Acid Schiff (AB-PAS) staining and TEM to evaluate phenotypic changes. For quantitative measurements (microvilli length and mitochondrial counts per enterocyte), representative images from each experimental group were analyzed using the FIJI image analysis software (n = 3). Histological scoring was performed based on categories including lumen morphology, microvilli architecture, epithelial morphology, organelle integrity, and goblet cells. Each morphological parameter was evaluated on a scale from 0 to 3, with a maximum score of 3 indicating the most severe damage. The detailed criteria are listed in Supplementary Table 1.

Microbiota-Depleted Zebrafish Model and Inoculation with Morganella morganii

Embryos were reared under aseptic conditions in E3 medium supplemented with a combination of antibiotics, including ampicillin (100 μg/mL), kanamycin (5 μg/mL), and amphotericin B (250 ng/mL) from 4 hpf. At 4 dpf, microbial depletion was verified by plating of larval homogenates on Luria agar (24 h, 30 °C) and comparing the results with standard E3 controls. The sterility test process was repeated for every batch of reared larvae. Upon confirmation, larvae were either maintained under antibiotic conditions or exposed to Morganella morganii (ATCC25830, 104 CFU/mL) until NP exposure on 6 dpf. At the end of 48 h exposure to 100 nm NP, larvae were collected for gut lumen histology and RT-qPCR analysis of inflammatory and tight junction markers.

RT-qPCR Analysis

To evaluate NP-induced inflammatory responses and tight junction disruptions, the relative expression levels of genes including interleukin-1β (IL-1β), nitric oxide synthase 2a (NOS2A), interleukin-13 (IL-13), zonula occludens-1 (ZO-1), Occludin, and Claudin-7 were analyzed. Expression levels were normalized to β-actin relative to untreated controls by using the 2–ΔΔCt method. Detailed experimental procedures are described in the Supporting Information.

16S rRNA Gene Sequencing and Data Analysis

To characterize NP-induced alterations in commensal gut microbiota, dissected intestinal samples from zebrafish larvae were subjected to 16S rRNA gene sequencing using the Illumina NovaSeq 6000 platform. Microbial community changes were analyzed across multiple taxonomic levels (phylum to genus). Spearman correlation analysis examined relationships among microbiota composition, histopathological markers, and gene expression profiles. Predictive functional analysis was performed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. All bioinformatics analyses were conducted via Omicsmart (https://www.omicsmart.com), an interactive online analysis platform. Detailed experimental procedures are described in the Supporting Information.

Statistical Analysis

All exposures were performed with at least three biological replicates, and all data are reported as the mean ± standard error of the mean (SEM). All statistical analyses were carried out using GraphPad Prism 10 software (GraphPad Software, CA, USA). When comparing more than three groups, one-way analysis of variance (ANOVA) followed by Tukey’s multiple comparison for parametric data set and, for nonparametric data analysis, Kruskal–Wallis test followed by Dunn’s multiple comparison were performed. A statistically significant difference against the control group was indicated with * (* p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001), and pairwise comparison between NP-exposure groups is indicated as # (# p < 0.05, ## p < 0.01, ### p < 0.001, #### p < 0.0001).

RESULTS and DISCUSSION

Physicochemical Characterization of PS and PMMA NPs

The representative TEM images confirmed the spherical morphology of all NPs and indicated that the particle sizes were approximately 103.2 ± 2.87 nm for PS, 85.07 ± 0.82 nm for PS-COOH, 84.27 ± 1.31 nm for PMMA, and 84.68 ± 0.89 nm for PMMA-COOH, respectively (Figure a). FTIR analysis revealed characteristic fingerprint regions (500 to 1200 cm–1), showing strong spectral overlap between PS and PS-COOH (Figure b). In contrast, PMMA and PMMA-COOH exhibited distinct fingerprint regions, with carboxyl surface modification inducing a more pronounced spectral change in PMMA (Figure c). Notably, PMMA displayed a prominent carbonyl (CO) stretching vibration at 1730 cm–1 among the four NPs (Figure d). ,, Zeta potential measurements demonstrated negative surface charges for all NPs in E3 medium with no significant differences between groups (Figure e). Hydrodynamic size analysis revealed significantly larger sizes for pristine NPs compared to those of carboxyl-modified counterparts (Figure f), indicating greater aggregation propensity in unmodified particles.

1.

1

Open in a new tab

Physicochemical characterization of PS and PMMA NPs. (a) Representative TEM images of NP particles; error bar = 100 nm. (b–d) FTIR spectra of the four NPs presented by grouping according to the parent particle type. Spectra of PS and PS-COOH are superimposed in (b) and PMMA and PMMA-COOH in (c). Spectra in (d) show four spectra superimposed and enlarged at wavenumber 1700 cm–1. (e) Zeta potential measurements of four NPs in zebrafish larvae media. (f) The hydrodynamic sizes of four NPs in zebrafish larvae media. All data are presented as mean ± SEM. **** p < 0.0001.

Carboxyl Modification Mitigates PS- but Not PMMA-Induced Gut Inflammation

To assess NP effects on intestinal histology and inflammation, zebrafish larvae were exposed to the four particles at a nonlethal dose for 48 h (Figure S1). Histopathological analysis revealed that PMMA exposure caused a loss of crypt and villus structures characteristic of healthy intestines (Figure a). AB-PAS staining provided complementary visualization of mucin distribution and goblet cell morphology; the overall mucosal architecture appeared comparable across groups. In contrast, TEM imaging showed that PS NPs induced the most severe morphological alterations in intestinal epithelial cells (IECs), characterized by irregular microvilli length and shape, loss of cell wall rigidity, increased vacuolization, reduced mitochondrial counts, and elevated luminal bacterial presence. Quantitative ultrastructural measurements, including microvillus length and mitochondrial number, were obtained from TEM images (Figures b and S2). Histological analysis was based on five equally weighted indicators (lumen morphology, microvillus architecture, epithelial morphology, organelle integrity, and goblet cell status; Supplementary Table 1) and demonstrated that the pristine PS NPs exhibited the highest cumulative injury score, while carboxylation substantially mitigated these effects (Figure c). In contrast, no significant differences were observed between the PMMA and the PMMA-COOH groups, highlighting the distinct efficacy of carboxylation (Figure c). Notably, no particle internalization was observed postexposure based on the TEM images.

2.

2

Open in a new tab

Intestinal histopathology and inflammatory marker alterations indicating NP-induced dysbiosis. (a) Representative images of intestinal cross sections stained with H&E (top) and AB-PAS (bottom) after 48-h exposure to NPs at 100 mg/L. (b) TEM images of zebrafish intestinal cross sections showing the gut lumen and their microvilli (MV) integrity, magnifications at 2,000X (scale bar = 5 μm) and 5,000X (scale bar = 2 μm). Yellow arrows indicate examples of MV used for length measurement. Nucleus (N), mitochondria (M), bacteria (B). (c) Histology scores of zebrafish larvae exposed to NPs. The radar plot (right) displays distinct damage patterns across five morphological categories. (d) Heatmap of relative mRNA expression changes in zebrafish larvae exposed to NPs. Data are presented as log2­(fold change) relative to the control group. Statistical significance against the control was indicated with * (* p < 0.05, ** p < 0.01, *** p < 0.001, and **** p < 0.0001).

Mitochondria are essential for sustaining epithelial energy metabolism and maintaining intestinal barrier integrity. Interestingly, a significant upregulation of tight junction genes (ZO-1, Occludin, and Claudin-7) was observed in the PS group, which was reversed by PS-COOH (Figure d and Figure S3), which could be a compensatory response to the compromised mitochondrial architecture and loss of numbers. These observations are consistent with prior evidence that epithelial mitochondrial stress triggers compensatory reinforcement of tight junction gene transcription to maintain barrier function. , In addition, mitochondrial dysfunction is known to be closely associated with intestinal inflammation due to its sensitivity toward oxidative stress; ,− we next analyzed inflammatory marker expression profiles. In contrast, PS groups did not significantly elicit the inflammatory marker expression. PMMA exposure, however, significantly upregulated the expression level of IL-1β (∼35-fold) and NOS2A (∼10-fold) but not IL-13 (Figure d and Figure S3). Carboxyl modification failed to attenuate PMMA-induced inflammation, with no significant reduction in gene expression levels compared to pristine PMMA. While Di Meo et al. associated NOS induction with mitochondrial inhibition via oxidative stress, PMMA NPs in our study elevated NOS2A without reducing mitochondrial counts. Although mitochondrial integrity, epithelial barrier regulation, and inflammatory signaling are recognized as interconnected aspects of intestinal homeostasis, the current findings indicate that the associations among these features are not direct or predictable. This suggests that NP-induced inflammation and histopathology may occur through noncanonical pathways, potentially involving gut-microbiota-mediated mechanisms.

PMMA Groups Exhibit Increased Abundance of Pathogenic Vibrio and Morganella

The intestinal barrier’s complex functionality arises from both its structural features and resident microbiome; we therefore next analyzed zebrafish gut microbiota following exposure. The α-diversity (Chao1 and Shannon) showed no significant changes in microbial richness or evenness across groups (Figure S4). In contrast, β-diversity analysis revealed that pristine NPs induced deviations from the controls, while carboxyl-modified NPs caused more distinct microbiome alterations, as visualized by principal coordinate analysis (PCoA; Figure a). Phylum-level analysis of the top ten most abundant taxa revealed an enrichment of Proteobacteria across exposure groups (Figure b), a change indicative of dysbiosis. Genus-level composition analysis further demonstrated differential abundance patterns in dominant taxa between pristine and carboxyl-modified groups (Figure c). LEfSe analysis (LDA score >4) identified group-specific enrichment of opportunistic pathogensAeromonas in PMMA-COOH-exposed larvae and Vibrio/Morganella in the PMMA group (Figure d). Quantification of the top ten genera revealed significant NP-driven changes: carboxyl-modified NPs (PS-COOH and PMMA-COOH) increased Aeromonas abundance relative to controls, while PMMA exposure uniquely amplified Vibrio (significantly higher than control, PS, and PMMA-COOH groups). Strikingly, both PMMA and PMMA-COOH elevated Morganella more than controls, with PMMA showing the highest abundance compared to pristine PS. Pristine PS NPs specifically reinforced Pseudomonas populations (Figure e).

3.

3

Open in a new tab

Composition analysis and indicator species analysis of microbial communities after NP exposure. (a) β-Diversity of microbial community illustrated by PCoA plot. (b) Phylum-level composition shows the relative abundance of the top ten dominant bacterial phyla across exposure groups. (c) Species composition analysis shows the top ten abundant taxa at the genus level. (d) Indicator species analysis employing LEfSe comparative analysis. The differentially abundant taxa enriched in microbiome with LDA scores ≥4 and p < 0.05 are shown. (e) Among the top ten genera in relative abundance, four taxa, Aeromonas, Vibrio, Morganella, and Pseudomonas, were significantly increased. Statistical analyses were performed with one-way ANOVA and the Kruskal–Wallis test. Each group contained three biological replicates (n = 3). Statistical significance against the control group was indicated with * (* p < 0.05 and ** p < 0.01), and pairwise comparison between NP-exposure groups was indicated with # (# p < 0.05, ## p < 0.01, ### p < 0.001). ns represented no significant difference.

Increased abundance of Aeromonas and Vibrio has been widely associated with epithelial stress and impaired host–microbe homeostasis in zebrafish. , Conversely, expansion of Pseudomonas and opportunistic Enterobacterales including Morganella reflects reduced colonization resistance and dysbiosis-driven ecological pressure with the gut. , The unique enrichment of Vibrio and Morganella in the PMMA NP exposure group suggests that pristine PMMA creates a gut microenvironment that is permissive to opportunistic pathogens, which is consistent with the epithelial stress and inflammation observed at the host level. In contrast, Aeromonas enrichment in the carboxyl-modified NP exposure groups reflects surface-chemistry-dependent shifts in particle–microbiota interactions, highlighting these species as biologically relevant responders to intestinal perturbation rather than dominant commensals.

Pathogenic Bacteria Correlates with Phenotypic Changes in PMMA Groups

To elucidate the relationships between microbial communities and host phenotypic, inflammatory, and tight junction markers, canonical correspondence analysis (CCA) was conducted. Exposure conditions were grouped to evaluate either NP-type effects (CTRL vs PS vs PMMA) or surface modification effects (CTRL vs PS/PS-COOH or CTRL vs PMMA/PMMA-COOH). The CCA diagram revealed that pristine NPs exhibited greater microbial diversity than controls (Figure a), with their communities positively correlating with inflammatory markers (IL-1β and NOS2A), as indicated by vector arrows. In contrast, carboxyl surface modification remarkably reduced the microbial diversity in both PS- (Figure b) and PMMA-exposed groups (Figure c). Correlation heatmaps of the top ten taxa further demonstrated stronger associations between PMMA/PMMA-COOH exposure and pathogenic bacteria compared to PS/PS-COOH groups (Figure d–f), and a significant positive correlation was noted between Morganella and the inflammation markers.

4.

4

Open in a new tab

Environmental factor correlation and predicted functional analysis of the microbial community exposed to NPs. (a–c) CCA plots demonstrating NP-type-induced changes in the larval zebrafish microbiome. Arrows in each plot illustrate how and how much each environmental factor influences the microbial community. Three comparisons were conducted: (a) CTRL/PS/PMMA (b) CTRL/PS/PS-COOH, and (c) CTRL/PMMA/PMMA-COOH. (d–f) Environmental factor analysis illustrated by correlation heat map using Spearman correlation coefficient at genus taxonomy level (* p < 0.05, ** p < 0.01, and *** p < 0.001). (g) PICRUSt2 functional analysis demonstrates signaling pathways that are significantly altered by carboxylation. Venn diagram showing numbers of the significantly affected pathways, with details shown by the Sankey diagram. The shared pathways in both pairwise comparisons are grouped in the red box.

Functional prediction via PICRUSt2 was further performed to identify carboxyl-modification-induced pathway alterations. Venn analysis (Figure g) revealed 61 and 48 pathways altered by PS-COOH and PMMA-COOH modification, respectively (p-values in Figure S5), with 38 shared pathways. Sankey plot analysis highlighted these shared pathways (red box, Figure g), demonstrating that carboxyl modification affects bacterial sulfur metabolism, amino acid metabolic pathways (including glutathione and pyruvate metabolism), biotin metabolism, and the NOD-like receptor signaling pathway. This indicates microbial redox and survival reprogramming that intersects with NOD-like receptor-mediated mucosal defense. Specifically, for the PS-COOH group, the enrichment of amino acid metabolism and NOD-like receptor signaling pathways provides mechanistic insight into the partial restoration of intestinal barrier function compared to the pristine PS NP exposure (Figure d and Figure S3). Amino acids such as glutamate and arginine act as an epithelial energy source and also modulate redox balance or polyamine pathways to promote epithelial restitution and barrier stability. Moreover, bacterial peptidoglycan turnover engages NOD2-RIP2-ATG16L1 to support autophagy and tight junction stability. , In contrast, PMMA-COOH enrichment of riboflavin biosynthesis and bacterial invasion of epithelial cells implies activation of mucosal defense pathways, which aligns with the observed incomplete recovery of barrier histology.

Validation of Gut Microbe Roles in PS- and PMMA-Induced Gut Dysbiosis

To verify the roles of gut microbiota in modulating the toxic effects induced by PS and PMMA exposure as well as the pathological effects of the associated bacteria, a microbiota-depleted zebrafish model was established using antibiotics in E3 medium (ABEM), followed by a challenge with Morganella morganii. Successful depletion was confirmed by the absence of bacterial colony formation from the fish homogenates (Figure S6). Markers, including phenotypic, inflammatory, and tight junction parameters, were evaluated. As illustrated in Figure a, various signs of intestinal epithelial damage were observed across exposure conditions in these antibiotic-treated fish, including blunting of microvilli, epithelial swelling or lifting, and altered lumen morphology. PMMA groups exhibited pronounced microvilli blunting, with PMMA-COOH showing greater epithelial edema than pristine PMMA. Strikingly, the increase in histology score following NP exposure was much lower in the ABEM condition compared to standard E3 (Figure b), suggesting a critical role for gut microbiota in NP toxicity. Importantly, histological scores were significantly increased in the ABEM + Morganella group compared with the ABEM condition alone for the PMMA groups. Furthermore, NP exposure induced transcriptional responses in inflammatory and tight junction markers that were microbiota-sensitive (Figure c, Figures S7 and S8). These effects were largely attenuated in ABEM-raised larvae but were reshaped by Morganella reconstitution. Alterations in inflammatory markers (IL-1β, NOS2A) were more pronounced in PMMA groups, whereas changes in tight junction markers (ZO-1, Occludin, Claudin-7) were more prominent in PS groups, highlighting the pathogenicity of Morganella.

5.

5

Open in a new tab

Validation of Morganella morganii-associated intestinal epithelial injury in a microbiota-depleted zebrafish model. (a) Representative H&E-stained intestinal cross sections of larvae exposed to NPs under two conditions: antibiotics E3 medium (ABEM, top row) or ABEM with Morganella morganii challenge (ABEM + Morganella, bottom row). (b) Normalized histology scores of larval intestines (dashed line = internal control baseline). Statistical significance against the control in each condition was indicated with * (* p < 0.05, ** p < 0.01, *** p < 0.001, and **** p < 0.0001), and # indicated statistical significance between the bacterial conditions for each NP (## p < 0.01, and #### p < 0.0001). ns represented no significant difference. (c) Heatmap of relative mRNA expression (log2 fold change) in larvae exposed to different NPs under three conditions: standard E3 medium, ABEM, and ABEM + Morganella. The color scale ranges from −5 (blue, downregulation) to +5 (red, upregulation); white denotes no change (0) relative to the control. Statistical significance against the control in each condition was indicated with * (* p < 0.05, ** p < 0.01, *** p < 0.001, and **** p < 0.0001).

Surface modification is widely employed to modulate NP properties, which in turn affects their biological behavior and outcomes. In this study, we found that carboxyl surface modification attenuates gut dysbiosis induced by PS, but not by PMMA, in zebrafish larvae, highlighting the modulatory role of the gut microbiota. Both PS and PMMA NPs induced measurable epithelial alterations and changes in inflammatory gene expression; however, carboxyl functionalization differentially modulated these responses. For PS-based NPs, the addition of the charged functional group reduced epithelial stress, consistent with the attenuation of mitochondrial and tight junction alterations in epithelial cells. This aligns with previous findings that negatively charged carboxylation results in less interaction with intestinal epithelial cells compared to positively charged amine-functionalized PS NPs, thereby causing less severe epithelial barrier disruption. In contrast, PMMA-COOH did not effectively alleviate the host responses observed in the pristine PMMA exposure group. This may be attributed to the persistent enrichment of opportunistic bacteria such as Vibrio and Morganella. Furthermore, predicted KEGG pathway analysis suggests that PMMA-COOH enriched pathways related to riboflavin biosynthesis. Intermediates of this pathway engage the MHC class I-related protein 1 (MR1) to activate mucosal-associated invariant T (MAIT) cells, which produce IL-17/IL-22 and modulate mucosal defense. This immunological link may contribute to the observed incomplete recovery of barrier histology in the PMMA-COOH group.

Morganella is a virulent, drug-resistant, biofilm-forming pathogen. While direct interactions between PMMA NPs and Morganella remain unexamined, PMMA’s biofilm propensity is well-documented in bone cements. Biofilm formation plays a key role in microbial pathogenicity, and Morganella is frequently identified in catheter-associated biofilms. , A bidirectional relationship has been reported between the carbonyl index of NPs and microbial adhesion, suggesting that surface chemistry critically influences bacterial attachment. , In particular, Morganella biofilms on plastic substrates demonstrate high antibiotic resistance, underscoring the need for mechanistic studies on PMMA–microbe interactions. Concurrently, PMMA exposure enriched Vibrio, another opportunistic pathogen that antagonized commensal Aeromonas, disrupted intestinal morphology and increased NOS2A expression. This pathogenicity likely involves type VI secretion-system-mediated competition with Aeromonas, potentially amplifying neutrophil-driven immune responses. These observations align with PMMA-specific pathway alterations, such as “biofilm formationVibrio cholerae” and “bacterial secretion system” (Figure S9).

PMMA is the predominant material for prosthodontic devices, and recent work indicates the inadvertent ingestion of the PMMA-based MNPs generated during the dental procedures and routine denture wear. It is reported that these particulates may contribute to inflammatory responses and microbial disturbances. , Although PMMA-based prostheses have been previously shown to shift the oral microbiome, our study extends this interaction to the gut by demonstrating polymer-type- and surface-modification-dependent dysbiosis and impaired intestinal barrier function. By evaluating PMMA alongside the widely studied PS NPs, we further identify PMMA-specific dysbiotic effects that have remained underexplored, despite its extensive clinical use. These systemic insights highlight plausible biological pathways through which PMMA-derived particulates may exert broader health implications beyond the oral cavity.

Furthermore, our results raise important safety concerns, particularly in light of emerging evidence that microplastic degradation products may serve as carbon sources for both gut microbiota and intestinal epithelial cells, thereby reshaping metabolic pathways and exacerbating inflammatory responses. − Though no biofragmentation was identified in the acute exposure scenario in this study (Figure S10), the effects of biotransformation of NPs in determining their biological activities in the intestinal environment remain a critical area for future investigation. Moreover, the size of plastic particles is a crucial determinant of their bioavailability, cellular uptake, interactions with gut microbiota, and subsequent toxicity. ,, Future studies dissecting the specific roles of biotransformation and size will be essential to elucidate how factors beyond surface modifications influence host–microbiota interactions and the resulting adverse outcomes.

Contextualizing these findings also requires acknowledgment of the limitations of the present study. Although zebrafish larvae are widely utilized for toxicological assessment, species-specific differences in physiology and developmental biology may limit their direct translation to mammalian systems. Nevertheless, the use of an aquatic organism provides a distinct advantage for evaluating NP toxicity, as NPs inevitably enter aquatic ecosystems, and early life aquatic species are among the first to encounter them. Accordingly, the zebrafish model allows the assessment of NP–host–microbiota interactions within an ecologically relevant context. Although the concentration used exceeds environmentally measured levels, it represents a nonlethal dose within the range commonly applied in prior zebrafish studies. This controlled high dose facilitates reproducible mechanistic evaluation, while underscoring the need for future studies involving chronic and lower-dose exposures to refine environmental relevance.

Conclusion

In conclusion, this study demonstrates that carboxyl surface modification differentially mitigates gut dysbiosis induced by PS and PMMA NPs in zebrafish larvae. While carboxylation effectively reduced PS NP toxicitypreventing epithelial damage and pathogenic bacterial overgrowthit failed to attenuate PMMA NP-induced gut inflammation, which showed strong associations with pathogenic Morganella and Vibrio proliferation. Functional analyses revealed that carboxyl modification significantly altered key microbial pathways, including amino acid metabolism and NOD-like receptor signaling, which are both critical for maintaining intestinal homeostasis. Critically, the roles of gut microbiota and the pathological effects of Morganella in modulating the toxic effects induced by PS and PMMA were verified by a microbiota-depletion model. These findings provide mechanistic insights into how polymer core composition and surface chemistry collectively govern NP–biological interactions across the intestinal barrier system, underscoring the necessity of material-specific safety evaluations and regulatory considerations.

Supplementary Material

eh5c00633_si_001.pdf (1MB, pdf)

Acknowledgments

This work was supported by the National Natural Science Foundation of China (22306145), the Tongji University Medicine-X Interdisciplinary Research Initiative (2025-0553-ZD-04), Foundation of Key Laboratory of Yangtze River Water Environment, Ministry of Education (Tongji University), China (YRWESF202502), and the Special Funds of the Tongji University for “Sino-German Cooperation 2.0 Strategy”. The TOC graphic was created with BioRender.com.

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/envhealth.5c00633.

  • Expanded experimental details (zebrafish maintenance; RT-qPCR protocol with primer sequences; 16S rRNA sequencing and analysis; and NP biotransformation analysis) and supporting figures: zebrafish larvae survival across NP concentrations (Figure S1); ultrastructural readouts of intestinal dysbiosismicrovilli length and mitochondrial counts (Figure S2); RT-qPCR profiles of inflammatory (IL-1β, NOS2A, IL-13) and tight junction (ZO-1, Occludin, Claudin-7) markers (Figure S3); α-diversity indices (Chao1, Shannon) (Figure S4); PICRUSt2-predicted KEGG pathways altered by carboxylation of PS and PMMA NPs (Figure S5); sterility verification of the microbiota-depleted model (ABEM) (Figure S6); gene expression profiles under ABEM and ABEM + Morganellainflammatory markers (Figure S7) and tight junction markers (Figure S8); PMMA-specific altered KEGG signaling pathways (Figure S9); and NP biotransformation analysis by TEM, SEM, and FTIR (Figure S10); a detailed histology scoring rubric is provided in Supplementary Table 1 (PDF)

The authors declare no competing financial interest.

Published as part of Environment & Health special issue “Micro- and Nano-plastics: What's Hidden Beneath”.

References

  1. Borrelle S. B., Ringma J., Law K. L., Monnahan C. C., Lebreton L., McGivern A., Murphy E., Jambeck J., Leonard G. H., Hilleary M. A.. et al. Predicted growth in plastic waste exceeds efforts to mitigate plastic pollution. Science (New York, N.Y.) 2020;369(6510):1515–1518. doi: 10.1126/science.aba3656. [DOI] [PubMed] [Google Scholar]
  2. Li Y., Tao L., Wang Q., Wang F., Li G., Song M.. Potential health impact of microplastics: A review of environmental distribution, human exposure, and toxic effects. Environ. Health. 2023;1(4):249–257. doi: 10.1021/envhealth.3c00052. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Sun A., Wang W.. Human exposure to microplastics and its associated health risks. Environ. Health. 2023;1(3):139–149. doi: 10.1021/envhealth.3c00053. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Ruan X., Ao J., Ma M., Jones R. R., Liu J., Li K., Ge Q., Xu G., Liu Y., Wang T.. et al. Nanoplastics detected in commercial sea salt. Environ. Sci. Technol. 2024;58(21):9091–9101. doi: 10.1021/acs.est.3c11021. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Luo T., Wang D., Zhao Y., Li X., Yang G., Jin Y.. Polystyrene microplastics exacerbate experimental colitis in mice tightly associated with the occurrence of hepatic inflammation. Sci. Total Environ. 2022;844:156884. doi: 10.1016/j.scitotenv.2022.156884. [DOI] [PubMed] [Google Scholar]
  6. Mahadevan G., Valiyaveettil S.. Understanding the interactions of poly­(methyl methacrylate) and poly­(vinyl chloride) nanoparticles with BHK-21 cell line. Sci. Rep. 2021;11(1):2089. doi: 10.1038/s41598-020-80708-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Gomes T., Almeida A. C., Georgantzopoulou A.. Characterization of cell responses in Rhodomonas baltica exposed to PMMA nanoplastics. Sci. Total Environ. 2020;726:138547. doi: 10.1016/j.scitotenv.2020.138547. [DOI] [PubMed] [Google Scholar]
  8. Hong Y., Feng Y., Yan T., Zhang L., Zhao Q., Zhao Q., Huang J., Huang S., Zhang Y.. Take-out food enhances the risk of MPs ingestion and obesity, altering the gut microbiome in young adults. J. Hazard Mater. 2024;476:135125. doi: 10.1016/j.jhazmat.2024.135125. [DOI] [PubMed] [Google Scholar]
  9. Venâncio C., Savuca A., Oliveira M., Martins M. A., Lopes I.. Polymethylmethacrylate nanoplastics effects on the freshwater cnidarian Hydra viridissima. J. Hazard. Mater. 2021;402:123773. doi: 10.1016/j.jhazmat.2020.123773. [DOI] [PubMed] [Google Scholar]
  10. Koelmans A. A., Mohamed Nor N. H., Hermsen E., Kooi M., Mintenig S. M., De France J.. Microplastics in freshwaters and drinking water: Critical review and assessment of data quality. Water Res. 2019;155:410–422. doi: 10.1016/j.watres.2019.02.054. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Guo Z., Li J., Zhang Z.. Meta-analysis for systematic review of global micro/nano-plastics contamination versus various freshwater microalgae: Toxicological effect patterns, taxon-specific response, and potential eco-risks. Water Res. 2024;258:121706. doi: 10.1016/j.watres.2024.121706. [DOI] [PubMed] [Google Scholar]
  12. Hidalgo-Ruz V., Gutow L., Thompson R. C., Thiel M.. Microplastics in the marine environment: A review of the methods used for identification and quantification. Environ. Sci. Technol. 2012;46(6):3060–3075. doi: 10.1021/es2031505. [DOI] [PubMed] [Google Scholar]
  13. Ali U., Abd K. K. J. B., Buang N. A.. A review of the properties and applications of poly (methyl methacrylate) (PMMA) Polym. Rev. 2015;55(4):678–705. doi: 10.1080/15583724.2015.1031377. [DOI] [Google Scholar]
  14. Gao X., Ge J., Li W., Zhou W., Xu L., Geng D.. NF-κB/let-7f-5p/IL-10 pathway involves in wear particle-induced osteolysis by inducing M1 macrophage polarization. Cell Cycle. 2018;17(17):2134–2145. doi: 10.1080/15384101.2018.1515549. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Shanmugasundar S., Kannan N., Sundaravadivel E., Zsolt S., Mukunthan K. S., Manokaran J., Narendranath J., Kamalakannan V. P., Kavitha P., Prabhu V.. et al. Study on the inflammatory response of PMMA/polystyrene/silica nanocomposite membranes for drug delivery and dental applications. PloS one. 2019;14(3):e0209948. doi: 10.1371/journal.pone.0209948. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Feuser P. E., Gaspar P. C., Ricci-Júnior E., Silva M. C. S. d., Nele M., Sayer C., H. H. de Araújo P.. Synthesis and characterization of poly­(methyl methacrylate) PMMA and evaluation of cytotoxicity for biomedical application. Macromol. Symp. 2014;343(1):65–69. doi: 10.1002/masy.201300194. [DOI] [Google Scholar]
  17. Zafar M. S.. Prosthodontic applications of polymethyl methacrylate (PMMA): An update. Polymers (Basel) 2020;12(10):2299. doi: 10.3390/polym12102299. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Vosshage A. T. L., Neu T. R., Gabel F.. Plastic alters biofilm quality as food resource of the freshwater gastropod radix balthica. Environ. Sci. Technol. 2018;52(19):11387–11393. doi: 10.1021/acs.est.8b02470. [DOI] [PubMed] [Google Scholar]
  19. Booth A. M., Hansen B. H., Frenzel M., Johnsen H., Altin D.. Uptake and toxicity of methylmethacrylate-based nanoplastic particles in aquatic organisms. Environ. Toxicol. Chem. 2015;35(7):1641–1649. doi: 10.1002/etc.3076. [DOI] [PubMed] [Google Scholar]
  20. Yao M., Mu L., Gao Z., Hu X.. Persistence of algal toxicity induced by polystyrene nanoplastics at environmentally relevant concentrations. Sci. Total Environ. 2023;876:162853. doi: 10.1016/j.scitotenv.2023.162853. [DOI] [PubMed] [Google Scholar]
  21. Zou W., Xia M., Jiang K., Cao Z., Zhang X., Hu X.. Photo-oxidative degradation mitigated the developmental toxicity of polyamide microplastics to zebrafish larvae by modulating macrophage-triggered proinflammatory responses and apoptosis. Environ. Sci. Technol. 2020;54(21):13888–13898. doi: 10.1021/acs.est.0c05399. [DOI] [PubMed] [Google Scholar]
  22. Zheng P. C., Pan X. Q., Zhou Y. J., Lai K. P., Li R., Zhang X. X.. Unraveling the impact of micro- and nano-sized polymethyl methacrylate on gut microbiota and liver lipid metabolism: Insights from oral exposure studies. Environ. Pollut. 2025;373:126157. doi: 10.1016/j.envpol.2025.126157. [DOI] [PubMed] [Google Scholar]
  23. Werorilangi S., Wicaksono E. A., Afdal M., Sari K., Nimzet R., Samad W., Mawadda R., Gosalam S., Fachruddin L., Massinai A.. et al. Ingested microplastics: a comparative analysis of contaminated shellfish from two sites in the Makassar Strait. Environ. Monit. Assess. 2025;197(4):364. doi: 10.1007/s10661-025-13804-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Gerhard C., Mielke G., Tasche D.. C4F8 plasma treatment for the modification of the focal length of liquid-based plano-convex lenses on different substrates. Appl. Phys. A: Mater. Sci. Process. 2020;126(10):769. doi: 10.1007/s00339-020-03946-z. [DOI] [Google Scholar]
  25. Rasmussen M. K., Pedersen J. N., Marie R.. Size and surface charge characterization of nanoparticles with a salt gradient. Nat. Commun. 2020;11(1):2337. doi: 10.1038/s41467-020-15889-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Chikaura H., Nakashima Y., Fujiwara Y., Komohara Y., Takeya M., Nakanishi Y.. Effect of particle size on biological response by human monocyte-derived macrophages. Biosurf. Biotribol. 2016;2(1):18–25. doi: 10.1016/j.bsbt.2016.02.003. [DOI] [Google Scholar]
  27. da Silva Brito W. A., Singer D., Miebach L., Saadati F., Wende K., Schmidt A., Bekeschus S.. Comprehensive in vitro polymer type, concentration, and size correlation analysis to microplastic toxicity and inflammation. Sci. Total Environ. 2023;854:158731. doi: 10.1016/j.scitotenv.2022.158731. [DOI] [PubMed] [Google Scholar]
  28. Kim W., Lee D., Kim J., Jeong H., Chung J., Roh J., Kim W., Fu X., Shim S.. Characterization of the intestinal transport mechanism of polystyrene microplastics (MPs) and the potential inhibitory effect of green tea extracts on MPs intestinal absorption. Toxicol. in Vitro. 2024;97:105813. doi: 10.1016/j.tiv.2024.105813. [DOI] [PubMed] [Google Scholar]
  29. Yu C., Xu Y., Wei Y., Guo Y., Wang Y., Song P., Yu J.. Gut microbiota and liver metabolomics reveal the potential mechanism of Lactobacillus rhamnosus GG modulating the liver toxicity caused by polystyrene microplastics in mice. Environ. Sci. Pollut. Res. Int. 2024;31(4):6527–6542. doi: 10.1007/s11356-023-31564-8. [DOI] [PubMed] [Google Scholar]
  30. Yu J., Chen L., Wu B.. Size-specific effects of microplastics and lead on zebrafish. Chemosphere. 2023;337:139383. doi: 10.1016/j.chemosphere.2023.139383. [DOI] [PubMed] [Google Scholar]
  31. Ferheen I., Spurio R., Mancini L., Marcheggiani S.. Detection of Morganella morganii bound to a plastic substrate in surface water. J. Global Antimicrob. Resist. 2023;32:104–107. doi: 10.1016/j.jgar.2023.01.008. [DOI] [PubMed] [Google Scholar]
  32. Huang Y., Chen Y., Xie H., Feng Y., Chen S., Bao B.. Effects of inducible nitric oxide synthase (iNOS) gene knockout on the diversity, composition, and function of gut microbiota in adult zebrafish. Biology. 2024;13(6):372. doi: 10.3390/biology13060372. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Chen M., Yue Y., Bao X., Feng X., Ou Z., Qiu Y., Yang K., Yang Y., Yu Y., Yu H.. Effects of polystyrene nanoplastics on oxidative stress, histopathology and intestinal microbiota in largemouth bass (Micropterus salmoides) Aquacult. Rep. 2022;27:101423. doi: 10.1016/j.aqrep.2022.101423. [DOI] [Google Scholar]
  34. Li G., Rong J., Xu X., Kwak E., Wang S., Qu G., Lin S., Peng G.. Distinct effects between polystyrene micro- and nanoplastics: exacerbation of adverse outcomes in inflammatory bowel disease-like zebrafish and mice. ACS Nano. 2025;19(15):15081–15099. doi: 10.1021/acsnano.5c02307. [DOI] [PubMed] [Google Scholar]
  35. Zhou C., Yang S., Ka W., Gao P., Li Y., Long R., Wang J.. Association of gut microbiota with metabolism in rainbow trout under acute heat stress. Front. Microbiol. 2022;13:846336. doi: 10.3389/fmicb.2022.846336. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Gao Y., Jin Q., Gao C., Chen Y., Sun Z., Guo G., Peng J.. Unraveling differential transcriptomes and cell types in zebrafish larvae intestine and liver. Cells. 2022;11(20):3290. doi: 10.3390/cells11203290. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Rawls J. F., Samuel B. S., Gordon J. I.. Gnotobiotic zebrafish reveal evolutionarily conserved responses to the gut microbiota. Proc. Natl. Acad. Sci. U.S.A. 2004;101(13):4596–4601. doi: 10.1073/pnas.0400706101. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Hernandez R. E., Galitan L., Cameron J., Goodwin N., Ramakrishnan L.. Delay of initial feeding of zebrafish larvae until 8 days postfertilization has no impact on survival or growth through the juvenile stage. Zebrafish. 2018;15(5):515–518. doi: 10.1089/zeb.2018.1579. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Licitra R., Fronte B., Verri T., Marchese M., Sangiacomo C., Santorelli F. M.. Zebrafish feed Intake: A systematic review for standardizing feeding management in laboratory conditions. Biology. 2024;13(4):209. doi: 10.3390/biology13040209. [DOI] [PMC free article] [PubMed] [Google Scholar]
  40. Huang W., Zhao T., Zhu X., Ni Z., Guo X., Tan L., Wang J.. The effects and mechanisms of polystyrene and polymethyl methacrylate with different sizes and concentrations on Gymnodinium aeruginosum. Environ. Pollut. 2021;287:117626. doi: 10.1016/j.envpol.2021.117626. [DOI] [PubMed] [Google Scholar]
  41. Marana M., Poulsen R., Thormar E., Clausen C., Thit A., Mathiessen H., Jaafar R., Korbut R., Hansen A., Hansen M.. et al. Plastic nanoparticles cause mild inflammation, disrupt metabolic pathways, change the gut microbiota and affect reproduction in zebrafish: A full generation multi-omics study. J. Hazard. Mater. 2022;424:127705. doi: 10.1016/j.jhazmat.2021.127705. [DOI] [PubMed] [Google Scholar]
  42. Pham L. N., Kanther M., Semova I., Rawls J. F.. Methods for generating and colonizing gnotobiotic zebrafish. Nat. Protoc. 2008;3(12):1862–1875. doi: 10.1038/nprot.2008.186. [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Sugumaran, D. ; Abd Karim, K. J. . Removal of copper (II) ion using chitosan-graft-poly­(methyl methacrylate) as adsorbent; 2017. 10.13140/RG.2.2.33911.93601. [DOI]
  44. Kalakonda P., Banne S.. Thermomechanical properties of PMMA and modified SWCNT composites. Nanotechnol Sci. Appl. 2017;10:45–52. doi: 10.2147/NSA.S123734. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Uddin J., Sharma A., Wu D., Tomar S., Ganesan V., Reichel P. E., Thota L. N. R., Cabrera-Silva R. I., Marella S., Idelman G.. STARD7 maintains intestinal epithelial mitochondria architecture, barrier integrity, and protection from colitis. JCI Insight. 2024;9(22):e172978. doi: 10.1172/jci.insight.172978. [DOI] [PMC free article] [PubMed] [Google Scholar]
  46. Haque P. S., Kapur N., Barrett T. A., Theiss A. L.. Mitochondrial function and gastrointestinal diseases. Nat. Rev. Gastroenterol. Hepatol. 2024;21(8):537–555. doi: 10.1038/s41575-024-00931-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  47. Li X., Huang Y., Zu D., Liu H., He H., Bao Q., He Y., Liang C., Luo G., Teng Y.. et al. PMMA nanoplastics induce gastric epithelial cellular senescence and cGAS-STING-mediated inflammation via ROS overproduction and NHEJ suppression. Ecotoxicol. Environ. Saf. 2024;287:117284. doi: 10.1016/j.ecoenv.2024.117284. [DOI] [PubMed] [Google Scholar]
  48. Guerbette T., Boudry G., Lan A.. Mitochondrial function in intestinal epithelium homeostasis and modulation in diet-induced obesity. Mol. Metab. 2022;63:101546. doi: 10.1016/j.molmet.2022.101546. [DOI] [PMC free article] [PubMed] [Google Scholar]
  49. Di Meo S., Reed T. T., Venditti P., Victor V. M.. Role of ROS and RNS sources in physiological and pathological conditions. Oxid Med. Cell Longev. 2016;2016:1245049. doi: 10.1155/2016/1245049. [DOI] [PMC free article] [PubMed] [Google Scholar]
  50. Gaulke C. A., Barton C. L., Proffitt S., Tanguay R. L., Sharpton T. J.. Triclosan exposure is associated with rapid restructuring of the microbiome in adult zebrafish. PloS one. 2016;11(5):e0154632. doi: 10.1371/journal.pone.0154632. [DOI] [PMC free article] [PubMed] [Google Scholar]
  51. Logan S. L., Thomas J., Yan J., Baker R. P., Shields D. S., Xavier J. B., Hammer B. K., Parthasarathy R.. The Vibrio cholerae type VI secretion system can modulate host intestinal mechanics to displace gut bacterial symbionts. Proc. Natl. Acad. Sci. U.S.A. 2018;115(16):E3779-E3787. doi: 10.1073/pnas.1720133115. [DOI] [PMC free article] [PubMed] [Google Scholar]
  52. Aoyama K., Nakaki T.. Glutathione in cellular redox homeostasis: Association with the excitatory amino acid carrier 1 (EAAC1) Molecules. 2015;20(5):8742–8758. doi: 10.3390/molecules20058742. [DOI] [PMC free article] [PubMed] [Google Scholar]
  53. Roager H. M., Licht T. R.. Microbial tryptophan catabolites in health and disease. Nat. Commun. 2018;9(1):3294. doi: 10.1038/s41467-018-05470-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  54. Benjamin J. L., Sumpter R. J., Levine B., Hooper L. V.. Intestinal epithelial autophagy is essential for host defense against invasive bacteria. Cell Host Microbe. 2013;13(6):723–734. doi: 10.1016/j.chom.2013.05.004. [DOI] [PMC free article] [PubMed] [Google Scholar]
  55. Parlato M., Yeretssian G.. NOD-Like receptors in intestinal homeostasis and epithelial tissue repair. Int. J. Mol. Sci. 2014;15(6):9594–9627. doi: 10.3390/ijms15069594. [DOI] [PMC free article] [PubMed] [Google Scholar]
  56. Edmans M. D., Connelley T. K., Morgan S., Pediongco T. J., Jayaraman S., Juno J. A., Meehan B. S., Dewar P. M., Maze E. A., Roos E. O.. MAIT cell-MR1 reactivity is highly conserved across multiple divergent species. J. Biol. Chem. 2024;300(6):107338. doi: 10.1016/j.jbc.2024.107338. [DOI] [PMC free article] [PubMed] [Google Scholar]
  57. Bertazzoni Minelli E., Della Bora T., Benini A.. Different microbial biofilm formation on polymethylmethacrylate (PMMA) bone cement loaded with gentamicin and vancomycin. Anaerobe. 2011;17(6):380–383. doi: 10.1016/j.anaerobe.2011.03.013. [DOI] [PubMed] [Google Scholar]
  58. Broomfield R. J., Morgan S. D., Khan A., Stickler D. J.. Crystalline bacterial biofilm formation on urinary catheters by urease-producing urinary tract pathogens: a simple method of control. J. Med. Microbiol. 2009;58(10):1367–1375. doi: 10.1099/jmm.0.012419-0. [DOI] [PubMed] [Google Scholar]
  59. Learman B. S., Brauer A. L., Eaton K. A., Armbruster C. E.. A rare opportunist, Morganella morganii, decreases severity of polymicrobial catheter-associated urinary tract infection. Infect. Immun. 2019;88(1):e00691-19. doi: 10.1128/IAI.00691-19. [DOI] [PMC free article] [PubMed] [Google Scholar]
  60. Cholewińska P., Moniuszko H., Wojnarowski K., Pokorny P., Szeligowska N., Dobicki W., Polechoński R., Górniak W.. The occurrence of microplastics and the formation of biofilms by pathogenic and opportunistic bacteria as threats in aquaculture. Int. J. Environ. Res. Public Health. 2022;19(13):8137. doi: 10.3390/ijerph19138137. [DOI] [PMC free article] [PubMed] [Google Scholar]
  61. Speranza G., Gottardi G., Pederzolli C., Lunelli L., Canteri R., Pasquardini L., Carli E., Lui A., Maniglio D., Brugnara M.. et al. Role of chemical interactions in bacterial adhesion to polymer surfaces. Biomaterials. 2004;25(11):2029–2037. doi: 10.1016/j.biomaterials.2003.08.061. [DOI] [PubMed] [Google Scholar]
  62. Xin G., Li W., Suman T. Y., Jia P., Ma Y., Pei D.. Gut bacteria Vibrio sp. and Aeromonas sp. trigger the expression levels of proinflammatory cytokine: First evidence from the germ-free zebrafish. Fish Shellfish Immunol. 2020;106:518–525. doi: 10.1016/j.fsi.2020.08.018. [DOI] [PubMed] [Google Scholar]
  63. Rolig A. S., Parthasarathy R., Burns A. R., Bohannan B J. M., Guillemin K.. Individual members of the microbiota disproportionately modulate host innate immune responses. Cell Host & Microbe. 2015;18(5):613–620. doi: 10.1016/j.chom.2015.10.009. [DOI] [PMC free article] [PubMed] [Google Scholar]
  64. Alqutaibi A. Y., Baik A., Almuzaini S. A., Farghal A. E., Alnazzawi A. A., Borzangy S., Aboalrejal A. N., AbdElaziz M. H., Mahmoud I. I., Zafar M. S.. Polymeric denture base materials: A review. Polymers. 2023;15(15):3258. doi: 10.3390/polym15153258. [DOI] [PMC free article] [PubMed] [Google Scholar]
  65. Chen Y., Chen J., Guo J., Yao M., Liu Y., Qian J., Ma Q.. Release of microplastics during dental procedures and denture wear: Impact on dental personnel and patients. J. Hazard. Mater. 2025;494:138463. doi: 10.1016/j.jhazmat.2025.138463. [DOI] [PubMed] [Google Scholar]
  66. Saha U., Jena S., Simnani F. Z., Singh D., Choudhury A., Naser S. S., Lenka S. S., Kirti A., Nandi A., Sinha A.. et al. The unseen perils of oral-care products generated micro/nanoplastics on human health. Ecotoxicol. Environ. Saf. 2025;290:117526. doi: 10.1016/j.ecoenv.2024.117526. [DOI] [PubMed] [Google Scholar]
  67. Bao L., Cui X., Zeng T., Liu G., Lai W., Zhao H., Gao F., Wu J., Leong K. W., Chen C.. Incorporation of polylactic acid microplastics into the carbon cycle as a carbon source to remodel the endogenous metabolism of the gut. Proc. Natl. Acad. Sci. U.S.A. 2025;122(19):e2417104122. doi: 10.1073/pnas.2417104122. [DOI] [PMC free article] [PubMed] [Google Scholar]
  68. Wang M., Li Q., Shi C., Lv J., Xu Y., Yang J., Chua S., Jia L., Chen H., Liu Q.. et al. Oligomer nanoparticle release from polylactic acid plastics catalysed by gut enzymes triggers acute inflammation. Nat. Nanotechnol. 2023;18(4):403–411. doi: 10.1038/s41565-023-01329-y. [DOI] [PubMed] [Google Scholar]
  69. Wu X., Zhang H., Chen J., Tan F., Cai R., Wang Y.. Photoaging promotes toxic micro/nanoplastics release from PLA/PBAT biodegradable plastic in gastrointestinal condition. Environ. Health. 2025;3(5):446–457. doi: 10.1021/envhealth.4c00209. [DOI] [PMC free article] [PubMed] [Google Scholar]
  70. Wang Y., Wang F., Song M.. New identities of micro- and nanoplastics formed from biological effects (bio-MNPs) Environ. Health. 2024;2(8):514–516. doi: 10.1021/envhealth.4c00072. [DOI] [PMC free article] [PubMed] [Google Scholar]
  71. Manuel P., Almeida M., Martins M., Oliveira M.. Effects of nanoplastics on zebrafish embryo-larval stages: A case study with polystyrene (PS) and polymethylmethacrylate (PMMA) particles. Environ. Res. 2022;213:113584. doi: 10.1016/j.envres.2022.113584. [DOI] [PubMed] [Google Scholar]
  72. Wang S., Al-Hasni N. S., Liu Z., Liu A.. Multifaceted aquatic environmental differences between nanoplastics and microplastics: behavior and fate. Environ. Health. 2024;2(10):688–701. doi: 10.1021/envhealth.4c00013. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

eh5c00633_si_001.pdf (1MB, pdf)

Articles from Environment & Health are provided here courtesy of American Chemical Society

RESOURCES