Probing the toxic interactions between polyvinyl chloride microplastics and Human Serum Albumin by multispectroscopic techniques

Studies on adsorption and synergistic biological effects induced by microplastic particles and the Platanus pollen allergenic protein 3(Pla a3)

Microplastics (MPs) are pervasive as emerging pollutants in ambient particles and may pose a potential threat to human health through respiratory exposure. Especially, impact of climate change has led to an extended blooming period for many plants, resulting in elevated pollen levels in the air, and leading to a continuous increase in the number of individuals suffering from allergenic diseases. However, the interactions between the MPs and allergenic proteins, remain largely unexplored. In this study, we investigated cellular toxicity of the MPs and Platanus pollen allergenic protein (Pla a3) based on the characterization of two typical microplastics (polystyrene, PS and polyethylene, PE). Our results indicated that UV irradiation could make surface alterations of the MPs, including breakage, particle size reduction, and an increase in surface oxygen-containing functional groups. These changes significantly enhanced the adsorption of the Pla a 3 protein. The 'protein coronas' formed by the MPs and the Pla a3 caused more damage to the A549 cells than Pla a3 alone. Reactive oxygen species (ROS) generation and elevated superoxide dismutase (SOD) levels increased significantly after the A549 cells were exposure to the protein coronas. This excessive oxidative stress led to significant inflammation and cytokine production increase, with IL-1β, IL-4, IFN-γ, and TNF-α levels rising by 1.84 ± 0.01, 2.37 ± 0.04, 1.94 ± 0.09, and 2.19 ± 0.05-fold times respectively compared to that of the Pla a 3 exposure alone. This study provided a fundamental data for further research for the allergenicity induced by the pollen proteins.

Exposure of Polystyrene Micro- and Nanoplastics to Simulated Human Digestive Enzymatic Systems: Structural and Functional Implications

The current in vitro study explores the exposure of the emerging pollutants polystyrene micro- and nanoplastics (PS-MNPs) within the digestive system and their interaction with key digestive enzymes such as α-amylase, pepsin, and pancreatin. The present research aims to elucidate the potential health implications of digestive enzymes by PS-MNPs based on the previously estimated mean of ingested microplastics (MPs) (0.714 g/day). The study deepens our understanding of the environmental pollutants' impact on human health by examining the interactions between polystyrene (PS) microplastics (PS MPs, 37-50 μm approx.) and PS nanoplastics (PS NPs, 100 nm) with digestive enzymes. The study analyzes the effects of micro- and nanosized plastics on enzyme activity using multiple spectroscopic techniques, revealing the molecular mechanisms of enzyme inhibition and structural changes caused by PS NPs, more than those by PS MPs. The fluorescence emission spectra indicated a static quenching mechanism across all the digestive enzymes at K q = 3.638, 4.615, and 1.855 (∼× 1018 M-1·s-1), predominantly affecting tyrosine (Tyr) and tryptophan (Trp) residues. Resonance light scattering (RLS) spectra confirmed the formation of enzyme-PS NPs complexes, leading to aggregation. Fourier transform infrared (FT-IR) and circular dichroism (CD) spectrometry results showed a decrease in protein content and structural alterations in the enzymes, potentially affecting their function. The half inhibitory concentration (IC50) values of PS NPs for salivary α-amylase (180 μg/mL), pepsin (580 μg/mL), and pancreatic protease (314 μg/mL) indicate uncompetitive inhibition, and that of pancreatic α-amylase (592 μg/mL) indicates mixed reversible inhibition of digestive enzymes. The study highlights the potential health risks associated with PS NPs exposure and gives a broader understanding of the interplay between environmental plastic pollutants and human health.

Factors affecting microplastic pollution of sandboxes in urban residential areas: Simple methodology for quality control in the context of potential exposure assessment for children

Occurrence of microplastics in the environment is well studied, but our knowledge of their distribution in specific locations, such as the sandboxes, which are integral parts of popular playgrounds for children, is limited. Pioneering research on the factors affecting the microplastic pollution of sandboxes in urban residential areas was conducted within three estates in Kielce, Poland. Sand samples (Σ27) were collected from nine sandboxes and examined for the presence of microplastics, using a simple quality control methodology proposed by the authors. Microplastics were found in each sample and their contents ranged from 60 to 5,540 items/kg of sand. Fragments and fibers were the most prevalent types of microplastics in the samples. They contributed to approximately 95% of all microplastics found. Transparent fibers were the most abundant among fibers (63%) and red particles (57%) among fragments. A strong, positive, and significant correlation (rSpearman = 0.90) was found between the number of microplastic items and the location of sandboxes (above sea level). There was no correlation between the population density of the estates (rSpearman  =  0.03), the distance of the estates from the center (rSpearman  =  0.02), and the distance of the estates from main roads (rSpearman  =  0.43). Considering that sandboxes can be a potential source of microplastics for children, and assuming that sand ingestion by children is similar to the estimated daily soil ingestion rate, our results indicate that the number of microplastics ingested could be 1,106. Inhalation, dermal transport, and ingestion of microplastic particles from sandboxes pose a potential threat to children's health. However, more research is needed to better understand the health risks associated with this source of microplastics.

Co-Existing Nanoplastics Further Exacerbates the Effects of Triclosan on the Physiological Functions of Human Serum Albumin

The potential health risks posed by the coexistence of nanoplastics (NPs) and triclosan (TCS) have garnered significant attention. However, the effects and underlying mechanisms of NPs and TCS on key functional proteins at the molecular level remain poorly understood. This study reports the effect of polystyrene nanoplastics (PSNPs) on the binding of TCS to human serum albumin (HSA) using multispectral methods and molecular simulation systems. The experimental results show that TCS significantly inhibits HSA esterase activity, with exacerbating inhibition in the presence of PSNPs, which is attributed to the alteration of HSA conformation and microenvironment of the amino acid residues induced by PSNPs. Molecular docking and site marker competitive studies indicate that TCS predominantly binds to site I of subdomain Sudlow II and the presence of PSNPs does not affect the binding sites. Spectra analyses indicate that the quenching mechanism between TCS and HSA belongs to the static quenching type and the presence of PSNPs does not change the fluorescence quenching type. The HSA fluorescence quenching and the conformational alterations induced by TCS are further enhanced in the presence of PSNPs, indicating that PSNPs enhance the binding of TCS to HSA by making TCS more accessible to the binding sites. This study provides valuable information about the toxicity of PSNPs and TCS in case of co-exposure.

Polyvinyl chloride (PVC), its additives, microplastic and human health: Unresolved and emerging issues

Polyvinyl chloride (PVC), a commonly used plastic across Europe, poses a number of risks at various stages of its life cycle. The carcinogenicity of PVC monomer, the need to use high number and volume of problematic additives, the easiness of fragmentation compared to other thermoplastics, the high volume of use in everyday products and the resulting extent to which European population is potentially exposed to both microplastics and chemicals and, finally, continuous problems during waste management, have raised concerns about impacts of PVC on human health and the environment for decades. As far back as in 2000, the European Commission recognized that PVC causes a wide range of serious problems for the environment and human health. More recently, in April 2022, PVC and its additives were included in the European Union's Restrictions Roadmap, and the European Chemicals Agency's investigation ruled that, to limit the use of some additives and to minimize releases of PVC microparticles, regulatory action would be necessary. Additionally, the Global Plastics Treaty discussions emphasise a need to ensure that plastics that remain in the economy are free of hazardous chemicals, including hazardous polymers. In this paper, we reviewed the available data on PVC microplastic, additives, the end of life options of products made of PVC, and how they all are connected. It is crucial to consider this polymer within the broader context of chemical pollution and circular economy, acknowledging that changes in how we manage our resources are necessary to achieve the goal for a truly non-toxic environment in the future.

Investigating the impact of nanoplastics in altering the efficacy of clarithromycin antibiotics through In vitro studies

Plastics have significant global implications due to their environmental contamination from extensive use and improper disposal. Among plastic particles, nanoplastics (<1 μm) pose notable risks to organisms and ecosystems due to their high surface area, reactivity, and potential to carry environmental pollutants. This study explores the interaction between polystyrene nanoplastics (PSNPs) and clarithromycin (CLA), a broad-spectrum antibiotic, focusing on their combined impact on insulin (INS) and antibiotic-resistant (AMR) bacteria. PSNPs can adsorb CLA, leading to structural changes in insulin and affecting its physiological functions, potentially causing insulin resistance. Additionally, PSNPs reduce CLA's inhibitory effects on pathogenic bacteria, facilitating antibiotic resistance. Our research utilized UV-Vis Spectroscopy, FTIR, Fluorescence spectroscopy, and Circular dichroism (CD) spectroscopy to assess INS structural changes, alongside the Kirby-Bauer disk diffusion method for microbiological examination. The findings highlight the synergistic and antagonistic effects of PSNPs and CLA, underscoring the enhanced toxicity of CLA when adsorbed onto PSNPs and the complex interactions affecting both human health and bacterial resistance. Further studies are essential to fully understand these mechanisms and their broader implications.

A physiologically based toxicokinetic model for microplastics and nanoplastics in mice after oral exposure and its implications for human dietary exposure assessment

Evidence of microplastics (MPs) and nanoplastics (NPs) in foods and daily-use products, along with their frequent detection in the human body, has raised concerns regarding their potential impact on human health through dietary ingestion. However, there is a lack of quantitative tools to simulate their bioaccumulation and tissue distribution following environmental exposure. To address this gap, we developed the first physiologically based toxicokinetic (PBTK) model for predicting the biodistribution of MPs and NPs in mice following oral exposure under various exposure scenarios. This novel model incorporated key kinetic mass transport processes, such as membrane permeability, albumin binding, and cellular uptake. We identified that the absorption rate in the gastrointestinal tract and fecal excretion rate constant had significant impacts on organ dosimetry. Our regression analysis indicated that the size-dependent dissociation constant and urine clearance rate constant sharply increased by a factor of 3 as NPs particle size increased to 1 µm. Finally, we developed a graphical user interface to enable interactive visualization and analysis for future applications, supporting human dietary exposure and risk assessment using available food consumption data and MPs/NPs residue data. The simulation results offer a mechanistic perspective, enhancing understanding of the internal organ dosimetry burden and health impacts from dietary exposure to MPs and NPs.

New molecular mechanism of nanoplastics affecting cadmium protein toxicity: Conformational response and differential binding of human serum albumin

The significant health risks of nanoplastics (NPs) and cadmium (Cd) are currently attracting a great deal of attention and research. At present, the effects and mechanisms of NPs and Cd on human serum albumin (HSA), a key functional protein in the organism on transportation, remain unknown. Here, the differences in the effects and mechanisms of action of Cd alone and composite systems (NPsCd) were explored by enzyme activity assay, multi-spectroscopy analysis and molecular docking. The results showed that HSA activity was inhibited and decreased to 80 % and 69.55 % (Cd = 30 mg/L) by Cd alone and NPs-Cd exposure, respectively. Exposure to Cd induced backbone disruption and protein defolding of HSA, and secondary structure disruption was manifested by the reduction of α-helix. Cd exposure also induces fluorescence sensitization of HSA. Notably, the addition of NPs further exacerbated the effects associated with Cd exposure, which was consistent with the changes in HSA activity. Thus, the above conformational changes may be responsible for inducing the loss of enzyme activity. Moreover, it was determined by RLS spectroscopy that NPs-Cd bound to HSA in the form of protein crowns. Molecular docking has further shown that Cd binds to the surface of Sudlow site II of HSA, suggesting that Cd impairs the function of HSA by affecting the protein structure. More importantly, the addition of NPs further exacerbated the disruption of the protein structure by the adherent binding of HSA on the surface of the plastic particles, which induced a greater change in the enzyme activity. This study provides useful perspectives for investigating the impact of composite pollution on HSA of human functional proteins.

A Comparative Study on the Interaction Between Protein and PET Micro/Nanoplastics: Structural and Surface Characteristics of Particles and Impacts on Lung Carcinoma Cells (A549) and Staphylococcus aureus

The interaction between particles and proteins is a key factor determining the toxicity responses of particles. Therefore, this study aimed to examine the interaction between the emerging pollutant polyethylene terephthalate micro/nanoplastics from water bottles with bovine serum albumin. The physicochemical characteristics of micro/nanoplastics were investigated using nuclear magnetic resonance, x-ray diffraction, Fourier transform infrared, dynamic light scattering, and x-ray energy dispersive spectroscopy after exposure to various concentrations and durations of protein. Furthermore, the impact of protein-treated micro/nanoplastics on biological activities was examined using the mitochondrial activity and membrane integrity of A549 cells and the activity and biofilm production of Staphylococcus aureus. The structural characteristics of micro/nanoplastics revealed an interaction with protein. For instance, the assignment of protein-related new proton signals (e.g., CH2, methylene protons of CH2O), changes in available protons s (e.g., CH and CH3), crystallinity, functional groups, elemental ratios, zeta potentials (-11.3 ± 1.3 to -12.4 ± 1.7 to 25.5 ± 2.3 mV), and particle size (395 ± 76 to 496 ± 60 to 866 ± 82 nm) of micro/nanoplastics were significantly observed after protein treatment. In addition, the loading (0.012-0.027 mM) and releasing (0.008-0.013 mM) of protein also showed similar responses with structural characteristics. Moreover, the cell-based responses were changed regarding the structural and surface characteristics of micro/nanoplastics and the loading efficiencies of protein. For example, insignificant mitochondrial activity (2%-10%) and significant membrane integrity (12%-28%) of A549 cells increased compared with control, and reductions in bacterial activity (5%-40%) in many cases and biofilm production specifically at low dose of all treatment stages (13%-46% reduction) were observed.

Individual mono and co-interactions of butylated hydroxytoluene and its metabolite with pepsin: Multi-pronged research strategies

In this study, the interactions between butylated hydroxytoluene (BHT) and its metabolite 2,6-Di-tert-butyl-p-benzoquinone (BHT-Q) with pepsin (PEP) were explored using multispectral measurements and computer prediction techniques. UV-vis absorption spectra, fluorescence lifetime, and Stern-Volmer quenching analysis showed static fluorescence quenching of PEP by BHT/BHT-Q. Negative thermodynamic parameters indicated that the spontaneous formation of complexes was primarily driven by van der Waals (vdW) forces and hydrogen bonds (HB). Synchronous fluorescence and circular dichroism spectroscopy revealed conformational changes induced by BHT/BHT-Q on PEP. Furthermore, BHT and BHT-Q inhibited PEP's enzymatic activity, while PEP suppressed their antioxidant activity. Interestingly, BHT-Q weakened BHT's binding strength to PEP, affecting the enzyme inhibition rate. Computer predictions highlighted the integral role of hydrophobic interactions. Moreover, BHT and BHT-Q exhibited different effects on the stability and compactness of PEP, the residue environment of PEP became more flexible or rigid in the presence of BHT and BHT-Q. Changes in the hydrophobic solvent accessible surface area (SASA) elucidated that the microenvironment of hydrophobic residues of PEP was changed after binding with BHT and BHT-Q. Ultimately, BHT's stronger binding affinity to PEP than BHT-Q was attributed mainly to its larger negative surface area, facilitating interactions with more amino acid residues.

Molecular and Energetic Descriptions of the Plasma Protein Adsorption onto the PVC Surface: Implications for Biocompatibility in Medical Devices

Protein adsorption on material surfaces plays a key role in the biocompatibility of medical devices. Therefore, understanding the complex interplay of physicochemical factors driving this kind of biofouling is paramount for advancing biomaterial design. In this study, we investigated the interaction of the most prominent plasma proteins with polyvinyl chloride (PVC) as one of the ubiquitous materials in medical devices. Through molecular docking, we identified human serum albumin (HSA) as a plasma protein with the highest affinity for adsorption onto the PVC surface with the binding energy of -25.9 kJ mol-1. Subsequently, utilizing triplicate molecular dynamics (MD) simulations (0.5 μs each), we quantitatively analyzed the interactions between HSA and PVC, probing potential structural changes in the protein upon adsorption. Our findings revealed that water-mediated hydrogen bonds and van der Waals forces are key contributors in stabilizing HSA onto the surface of PVC without significant alteration to its secondary and tertiary structures. The observed distribution of water molecules further highlights the importance of the hydration layer in facilitating and modulating protein-polymer interactions. We further evaluated the thermodynamic properties governing the adsorption process by calculating the potential of mean force (PMF) along the direction normal to the surface. The computed Gibbs free energy of adsorption at 300 K (-507.4 kJ/mol) indicated a thermodynamically favored and spontaneous process. Moreover, our investigations across different temperatures (290 to 310 K) consistently showed an enthalpy-driven adsorption process.

High-density polyethylene microplastics in agricultural soil: Impact on microbes, enzymes, and carbon-nitrogen ratio

Microplastics (MPs), recognized as emerging pollutants, pose a significant threat to diverse organisms and have adverse effects on agricultural soil. High-density polyethylene (HDPE) holds a prominent position among prevalent forms of MPs. In the current investigations, the impact of HDPE was assessed at four different concentrations (0.25%, 0.5%, 0.75%, and 1.0%) on agricultural soil, microbial population, exoenzymes activities including amylase, cellulase, and invertase, and alteration in carbon-to-nitrogen (C/N) ratio. Both bacterial and fungal populations exhibited a non-concentration-dependent response to different concentrations of HDPE over time. In this study, we refer to the concentrations of 0.25%, 0.5%, 0.75%, and 1.0% as HT1, HT2, HT3, and HT4, respectively. Initial MP application significantly reduced bacterial colony counts for HT1, HT2, and HT4, while HT3 showed no significant change. On the 60th day, HT1 and HT3 exhibited a higher bacterial colony count compared to the control. On the other hand, fungal populations increased to maximum on day 1 but displayed no distinct time-dependent trend from days 15 to 60. Furthermore, enzyme activities decreased with increasing concentrations of MPs over an extended period. Molecular docking studies suggest that HDPE can hinder enzyme activity by forming hydrogen bonds with enzymes. The C/N ratio was found to be significantly higher in MP-treated soils on the 60th day relative to control, suggesting relatively slower degradation of carbon compounds in the MP-treated soils.

Resilient forward osmosis membranes against microplastics fouling enhanced by MWCNTs/UiO-66-NH2 hybrid nanoparticles

The escalating presence of microplastics (MPs) in wastewater necessitates the investigation of effective tertiary treatment process. Forward osmosis (FO) emerges as an effective non-pressurized membrane process, however, for the effective implementation of FO systems, the development of fouling-resistance FO membranes with high-performance is essential. This study focuses on the integration of MWCNT/UiO-66-NH2 as metal-organic frameworks (MOFs) and multi-wall carbon nanotubes (MWCNT) nanocomposites in thin film composite (TFC) FO membranes, harnessing the synergistic power of hybrid nanoparticles in FO membranes. The results showed that the addition of MWCNT/UiO-66-NH2 in the aqueous phase during polyamide formation changed the polyamide surface structure, and enhanced membranes' hydrophilicity by 44%. The water flux of the modified FO membrane incorporated with 0.1 wt% MWCNTs/UiO-66-NH2 increased by 67% and the reverse salt flux decreased by 22% as in comparison with the control membrane. Moreover, the modified membrane showed improved antifouling behavior against both organic foulant and MPs. The MWCNT/UiO-66-NH2 membrane experienced 35% flux decline while the control membrane experienced 65% flux decline. This proves that the integration of MWCNT/UiO-66-NH2 nanoparticles into TFC FO membranes is a viable approach in creating advanced FO membranes with high antifouling propensity with potential to be expanded further to other membrane applications.

Influence of para-substituted benzaldehyde derivatives with different push/pull electron strength groups on the conformation of human serum albumin and toxicological effects in zebrafish

Excessive intake of benzaldehyde and its derivatives can cause irreversible damage to living organisms. Hence, benzaldehyde derivatives with different para-substitutions of push/pull electronic groups were chosen to investigate the effect of different substituent properties on the structure of human serum albumin (HSA). The binding constants, number of binding sites, major interaction forces, protein structural changes, and binding sites of benzaldehyde (BzH) and its derivatives (4-BzHD) with HSA in serum proteins were obtained based on multispectral and molecular docking techniques. The mechanism of BzH/4-BzHD interaction on HSA is mainly static quenching and is accompanied by the formation of a ground state complex. BzH/4-BzHD is bound to HSA in a 1:1 stoichiometric ratio. The interaction forces for the binding of BzH/4-BzHD to HSA are mainly hydrogen bonding and hydrophobic interaction, which are also accompanied by a small amount of electrostatic interactions. The effect of BzH/4-BzHD on HSA conformation follows: 4-Diethylaminobenzaldehyde (4-DBzH) > 4-Nitrobenzaldehyde (4-NBzH) > 4-Hydroxybenzaldehyde (4-HBzH) > 4-Acetaminobenzaldehyde (4-ABzH) > BzH, which means that the stronger push/pull electronic strength of the para-substituted benzaldehyde derivatives has a greater effect on HSA conformation. Furthermore, the concentration-lethality curves of different concentrations for BzH/4-BzHD on zebrafish verified above conclusion. This work provides a scientific basis for the risk assessment of benzaldehyde and its derivatives to the ecological environment and human health and for the environmental toxicological studies of benzaldehyde derivatives with different strengths of push/pull electron substitution.

Ovalbumin interaction with polystyrene and polyethylene terephthalate microplastics alters its structural properties

Contaminating microplastics can interact with food proteins in the food matrix and during digestion. This study investigated adsorption of chicken egg protein ovalbumin to polystyrene (PS, 110 and 260 μm) and polyethylene terephthalate (PET, 140 μm) MPs in acidic and neutral conditions and alterations in ovalbumin structure. Ovalbumin adsorption affinity depended on MPs size (smaller > larger), type (PS > PET) and pH (pH 3 > pH 7). In bulk solution, MPs does not change ovalbumin secondary structure significantly, but induces loosening (at pH 3) and tightening (at pH 7) of tertiary structure. Formed soft corona exclusively consists of full length non-native ovalbumin, while in hard corona also shorter ovalbumin fragments were found. At pH 7 soft corona ovalbumin has rearranged but still preserved level of ordered secondary structure, resulting in preserved thermostability and proteolytic stability, but decreased ability to form fibrils upon heating. Secondary structure changes in soft corona resemble changes in native ovalbumin induced by heat treatment (80 °C). Ovalbumin is abundantly present in corona around microplastics also in the presence of other egg white proteins. These results imply that microplastics contaminating food may bind and change structure and functional properties of the main egg white protein.

Probing the toxic effect of chlorpyrifos as an environmental pollutant on the structure and biological activity of lysozyme under physiological conditions

The pervasive use of pesticides like chlorpyrifos (CPY) has been associated with deleterious effects on biomolecules, posing significant risks to environmental integrity, public health, and overall ecosystem equilibrium. Accordingly, in this study, we investigated the potential binding interaction between the well-conserved enzyme, lysozyme (LSZ), and CPY through various spectroscopic techniques and molecular modeling. The UV-vis absorption and fluorescence experiments confirmed the complex formation and static quenching of the intrinsic fluorescence intensity. LSZ revealed a singular binding site for CPY, with binding constants around 105 M-1 across different temperature ranges. Analysis of thermodynamic parameters showed the spontaneous nature of the complexation process, while also revealing the pivotal role of hydrophobic interactions in stabilizing the LSZ-CPY system. According to circular dichroism and Fourier transform infrared studies, CPY binding changed the secondary structure of LSZ by boosting α-helix presence and reducing the levels of β-sheet and β-turn content. Further, CPY decreased the stability and activity of LSZ. Computational docking delineated the specific and highly preferred binding site of CPY within the structure of LSZ. Molecular dynamic simulation indicated the enduring stability of the LSZ/CPY complex and revealed structural modifications in the LSZ after binding with CPY. This research provides a detailed understanding of the intermolecular dynamics between CPY and LSZ, concurrently elucidating the molecular-level implications for the potential hazards of pesticides in the natural environment.

Studies on the binding of wedelolactone to human serum albumin with multi-spectroscopic analysis, molecular docking and molecular dynamic simulation

Wedelolactone (WEL) is a small molecule compound isolated from Eclipta prostrate L., which has been reported to possess various biological activities such as anti-hepatotoxicity, anti-hypertension, anti-tumour, anti-phospholipase A2 and detoxification activity against snake venom. In the present study, we investigated the interaction of WEL with human serum albumin (HSA) using simultaneous fluorescence, UV-visible spectroscopy, 3D fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), molecular docking technique and molecular dynamics simulation. We found that the interaction between HSA and WEL can exhibit a static fluorescence burst mechanism, and the binding process is essentially spontaneous, with the main forces manifested as hydrogen bonding, van der Waals force and electrostatic interactions. Competitive binding and molecular docking studies showed that WEL preferentially bound to HSA in substructural region IIA (site I); molecular dynamics simulations showed that HSA interacted with WEL to form a stable complex, which also induced conformational changes in HSA. The study of the interaction between WEL and HSA can provide a reference for a more in-depth study of the pharmacodynamic mechanism of WEL and its further development and utilisation.

Regulation mechanisms of ferric ions release from iron-loaded transferrin protein caused by nano-sized polystyrene plastics-induced conformational and structural changes

Currently, the binding of iron-binding protein transferrin (TF) with NPs and their interaction mechanisms have not been completely elucidated yet. Here, we probed the conformation-dependent release of Fe ions from TF induced by nano-sized polystyrene plastics (PS-NPs) using dialysis, ICP-MS, multi-spectroscopic techniques, and computational simulation. The results showed that the release of free Fe ions from TF was activated after PS-NPs binding, which displayed a clear dose-effect correlation. PS-NPs binding can induce the unfolding and loosening of polypeptide chain and backbone of TF. Alongside this we found that the TF secondary structure was destroyed, thereby causing TF protein misfolding and denaturation. In parallel, PS-NPs interacted with the chromophores, resulting in the occurrence of fluorescence sensitization effects and the disruption of the surrounding micro-environment of aromatic amino acids. Also, the binding of PS-NPs induced the formation of new aggregates in the PS-NPs-TF system. Further simulations indicated that PS-NPs exhibited a preference for binding to the hinge region that connects the C-lobe and N-lobe, which is responsible for the Fe ions release and structural alterations of TF. This finding provides a new understanding about the regulation of the release of Fe ions of iron-loaded TF through NPs-induced conformational and structural changes.

The weakened physiological functions of human serum albumin in presence of polystyrene nanoplastics

Due to the widespread presence of nanoplastics (NPs) in daily essentials and drinking water, the potential adverse effects of NPs on human health have become a global concern. Human serum albumin (HSA), the most abundant and multi-functional protein in plasma, has been chosen to understand the biological effects of NPs after entering the blood. The esterase activity and the transport of bisphenol A in the presence of polystyrene nanoplastics (PSNPs) under physiological conditions (pH 4.0 and 7.4) have been investigated to evaluate the possible biological effects. The interactions between PSNPs and HSA have also been systematically studied by multispectral methods and dynamic light scattering techniques. The esterase activity of HSA presented a decreased trend with increasing PSNPs; conversely, higher permeabilities are accompanied by higher amounts of PSNPs. Compared with the unchanged hydrodynamic diameter and weaker interactions at pH 7.4, stronger binding between HSA and PSNPs at pH 4.0 led to a significant increase in the particle size of the PSNPs-HSA complex. The quenching mechanism belonged to the static quenching type. The electrostatic force is proposed to be the dominant factor for PSNPs binding to HSA. The work provides some information about the toxicity of NPs when exposed to humans.

Adsorption of clarithromycin on polystyrene nanoplastics surface and its combined adverse effect on serum albumin

Emerging contaminants, such as antibiotics and nanoplastics, have garnered significant attention due to their potential adverse effects on diverse ecosystems. Antibiotic adsorption on the surface of nanoplastics potentially facilitates their long-range transport, leading to the synergistic effects of the complex. This research aims to examine the adsorption behavior of clarithromycin binding with polystyrene nanoplastics surface as well as their interaction between drug adsorbed polystyrene nanoplastics with serum albumin. Different spectroscopic methods were used to find out the interaction between clarithromycin and nanoplastics, under stimulated physiological conditions UV-vis spectroscopy showed a maximum of 22.8% percentage of the drug adsorbed with the polystyrene nanoplastics surface after 6 h of incubation. The fluorescence spectroscopic results demonstrated that the fluorescence intensity of serum albumin was quenched by the clarithromycin-polystyrene nanoplastics (CLA-PSNP) complex through static quenching. We calculated the number of binding stoichiometry, binding constants, and thermodynamic parameters. This study revealed that the CLA-PSNP binds to serum albumin spontaneously and its hydrophobic interactions played a significant role. The conformational changes in the structure of serum albumin were revealed from the findings of synchronous fluorescence spectra, CD spectra, and 3D fluorescence spectra, leading to the disturbance in functional activity. This study focuses valuable insights into the intermolecular interactions between clarithromycin-adsorbed polystyrene nanoplastics and serum albumin and its potential molecular-level biological toxicity.

Assessment of polystyrene nano plastics effect on human salivary α-amylase structural alteration: Insights from an in vitro and in silico study

The study found that the enzyme activity of human salivary α-amylase (α-AHS) was competitively inhibited by nanoplastic polystyrene (PS-NPs), with a half-inhibitory concentration (IC50) of 92 μg/mL, while the maximum reaction rate (Vmax) remained unchanged at 909 μg/mL•min. An increase in the concentration of PS-NPs led to a quenching of α-AHS fluorescence with a slight red shift, indicating a static mechanism. The binding constant (Ka) and quenching constant (Kq) were calculated to be 2.92 × 1011 M-1 and 1.078 × 1019 M-1• S-1 respectively, with a hill coefficient (n) close to one and an apparent binding equilibrium constant (KA) of 1.54 × 1011 M-1. Molecular docking results suggested that the interaction between α-AHS and PS-NPs involved π-anion interactions between the active site Asp197, Asp300 residues, and van der Waals force interactions affecting the Tyr, Trp, and other residues. Fourier transform infrared (FT-IR) and circular dichroism (CD) analyses revealed conformational changes in α-AHS, including a loss of secondary structure α-helix and β-sheet. The study concludes that the interaction between α-AHS and PS-NPs leads to structural and functional changes in α-AHS, potentially impacting human health. This research provides a foundation for further toxicological analysis of MPs/NPs in the human digestive system.

Risks Associated with the Presence of Polyvinyl Chloride in the Environment and Methods for Its Disposal and Utilization

Plastics have recently become an indispensable part of everyone's daily life due to their versatility, durability, light weight, and low production costs. The increasing production and use of plastics poses great environmental problems due to their incomplete utilization, a very long period of biodegradation, and a negative impact on living organisms. Decomposing plastics lead to the formation of microplastics, which accumulate in the environment and living organisms, becoming part of the food chain. The contamination of soils and water with poly(vinyl chloride) (PVC) seriously threatens ecosystems around the world. Their durability and low weight make microplastic particles easily transported through water or air, ending up in the soil. Thus, the problem of microplastic pollution affects the entire ecosystem. Since microplastics are commonly found in both drinking and bottled water, humans are also exposed to their harmful effects. Because of existing risks associated with the PVC microplastic contamination of the ecosystem, intensive research is underway to develop methods to clean and remove it from the environment. The pollution of the environment with plastic, and especially microplastic, results in the reduction of both water and soil resources used for agricultural and utility purposes. This review provides an overview of PVC's environmental impact and its disposal options.

Binding divergence of polystyrene nanoparticles with serum albumin caused by surface functionalization

Using a combination of spectroscopy, we devised an integrated structural strategy to comprehensively profile the molecular details of the impact of differently functionalized (plain, aminated, and carboxylated) polystyrene nanoparticles (PSNPs) on human serum albumin (HSA). The binding isotherms obtained from fluorescence and UV-vis absorption measurements demonstrate that surface functionalization can distinguish the interaction of PSNPs with HSA. Three-dimensional fluorescence and circular dichroism analysis of the effect of interaction with PSNPs on the native conformation and secondary structures of the protein reveals a diminution in the skeleton structure of HSA induced by the PSNPs. In accordance with this, it is discovered that the esterase activity of protein-PSNPs aggregates is diminished compared to that of the native protein. The carboxylated PSNPs exhibited the strongest protein binding and perturbation effects compared to other particles. Plain PSNPs exhibited significant hydrophobic interaction properties, as evidenced by spectral blue shifts and a diminished Stokes shift in the three-dimensional fluorescence assay. Our results exclusively highlight that the hydrophobic and surface charge characteristics of PSNPs govern the extent of interaction with the protein, which is beneficial to understanding microplastic toxicology.

Multispectroscopic Investigations of the Binding Interaction between Polyethylene Microplastics and Human Hemoglobin

In this investigation, different multispectroscopic analytical techniques have been used to explore the interaction between polyethylene microplastics (PE-MPs) and human hemoglobin (HHb), an oxygen carrier in the human blood circulatory system. Ultraviolet-visible absorption studies have demonstrated that HHb molecules may interact with PE-MPs, and thermal melting studies have indicated that PE-MPs have a stabilizing effect on HHb. Further circular dichroism and Fourier transform infrared spectroscopic studies have revealed the distinct changes in HHb's secondary structures caused by the formation of the HHb-PE-MP binding complex. These findings imply that PE-MPs could enter the blood circulation system of humans and may be hazardous to humans. This work explains the potential binding interaction of microplastics at the molecular level and offers insight into the intermolecular interaction between PE-MPs and HHb.

Unveiling the Modification of Esterase-like Activity of Serum Albumin by Nanoplastics and Their Cocontaminants

Nanoplastics and other cocontaminants have raised concerns due to their widespread presence in the environment and their potential to enter the food chain. The harmful effects of these particles depend on various factors, such as nanoparticle size, shape, surface charge, and the nature of the cocontaminants involved. On entering the human body, human serum albumin (HSA) molecules bind and transport these particles in the blood system. The esterase-like activity of HSA, which plays a role in metabolizing drug/toxic compounds, was taken as a representative to portray the effects of these particles on HSA. Polystyrene nanoplastics (PSNPs) with different surface functionalization (plain (PS), amine (PS-NH2), and carboxy (PS-COOH)), different sizes (100 and 500 nm), and PS with cocontaminant metformin hydrochloride (Met-HCl), a widely used antidiabetic drug, were investigated in this study. Fluorescence emission spectra of HSA revealed that PS-NH2 exhibits a greater effect on protein conformation, smaller NPs have a greater influence on protein structure than larger NPs, and Met-HCl lowers PSNPs' affinity for HSA by coating the surface of the NPs, which may result in direct NP distribution to the drug's target organs and toxicity. Circular dichroism spectra also supported these results in terms of secondary structural changes. Esterase activity of HSA was inhibited by all the particles (except Met-HCl) by competitive inhibition as concluded from constant Vmax and increasing Km. Greater reduction in enzyme activity was observed for PS-NH2 among functionalizations and for 100 nm PS among sizes. Furthermore, Met-HCl lowers the inhibitory impact of PSNPs on HSA since the drug binds weakly to HSA, and so they can serve as a vector delivering PSNPs to their target organs, resulting in serious implications.

Interactions between microplastics and contaminants: A review focusing on the effect of aging process

Microplastics (MPs) in the environment are a major global concern due to their persistent nature and wide distribution. The aging of MPs is influenced by several processes including photodegradation, thermal degradation, biodegradation and mechanical fragmentation, which affect their interaction with contaminants. This comprehensive review aims to summarize the aging process of MPs and the factors that impact their aging, and to discuss the effects of aging on the interaction of MPs with contaminants. A range of characterization methods that can effectively elucidate the mechanistic processes of these interactions are outlined. The rate and extent of MPs aging are influenced by their physicochemical properties and other environmental factors, which ultimately affect the adsorption and aggregation of aged MPs with environmental contaminants. Pollutants such as heavy metals, organic matter and microorganisms have a tendency to accumulate on MPs through adsorption and the interactions between them impact their environmental behavior. Aging enhances the specific surface area and oxygen-containing functional groups of MPs, thereby affecting the mechanism of interaction between MPs and contaminants. To obtain a more comprehensive understanding of how aging affects the interactions, this review also provides an overview of the mechanisms by which MPs interact with contaminants. In the future, there should be further in-depth studies of the potential hazards of aged MPs in different environments e.g., soil, sediment, aquatic environment, and effects of their interaction with environmental pollutants on human health and ecology.

Journey of micronanoplastics with blood components

The entry of micro- and nanoplastics (MNPs) into the human body is inevitable. They enter blood circulation through ingestion, inhalation, and dermal contact by crossing the gut-lung-skin barrier (the epithelium of the digestive tract, the respiratory tract, and the cutaneous layer). There are many reports on their toxicities to organs and tissues. This paper presents the first thorough assessment of MNP-driven bloodstream toxicity and the mechanism of toxicity from the viewpoint of both MNP and environmental co-pollutant complexes. Toxic impacts include plasma protein denaturation, hemolysis, reduced immunity, thrombosis, blood coagulation, and vascular endothelial damage, among others, which can lead to life-threatening diseases. Protein corona formation, oxidative stress, cytokine alterations, inflammation, and cyto- and genotoxicity are the key mechanisms involved in toxicity. MNPs change the secondary structure of plasma proteins, thereby preventing their transport functions (for nutrients, drugs, oxygen, etc.). MNPs inhibit erythropoiesis by influencing hematopoietic stem cell proliferation and differentiation. They cause red blood cell and platelet aggregation, as well as increased adherence to endothelial cells, which can lead to thrombosis and cardiovascular disease. White blood cells and immune cells phagocytose MNPs, provoking inflammation. However, research gaps still exist, including gaps regarding the combined toxicity of MNPs and co-pollutants, toxicological studies in human models, advanced methodologies for toxicity analysis, bioaccumulation studies, inflammation and immunological responses, dose-response relationships of MNPs, and the effect of different physiochemical characteristics of MNPs. Furthermore, most studies have analyzed toxicity using prepared MNPs; hence, studies must be undertaken using true-to-life MNPs to determine the real-world scenario. Additionally, nanoplastics may further degrade into monomers, whose toxic effects have not yet been explored. The research gaps highlighted in this review will inspire future studies on the toxicity of MNPs in the vascular/circulatory systems utilizing in vivo models to enable more reliable health risk assessment.

Evidence of microplastics release from polythene and paper cups exposed to hot and cold: A case study on the compromised kinetics of catalase

Microplastics (MPs) have become widespread in the modern world posing a hidden threat to the global environment. However, growing accumulation and devastating impact of MPs on human health and the environment have received least attention. In the current investigation, for the first time MPs have been identified which are released from the daily usable materials like polythene bags (PB) and paper cups (PC) in response to hot and cold water exposure at different time intervals. The impact of these MPs has been assessed on the major antioxidant enzyme, bovine liver catalase (BLC). The binding of MPs caused conformational changes in BLC by decreasing the α-helical content, which results in reduction of the enzymatic activity. Kinetics study revealed nearly ∼1.4-fold compromised catalytic efficiency of catalase in response to MPs. Nevertheless, hepatic catalase activity was also significantly decreased in presence of MPs. Further, materials like glass, porcelain, stainless steel, and high-grade plastics are discovered as greener alternatives to PB and PC.

Microplastics: Detection in human samples, cell line studies, and health impacts

Microplastics (MPs) are in all environmental compartments, including atmosphere, terrestrial, and aquatic environments as well as in marine organisms, foods, drinking water, and indoor and outdoor environments. MPs can enter the human body through the food chain and contaminated environment. Ingestion, inhalation, and dermal contact are the routes of their entry into the human body. Recent studies reporting the detection of MPs within the human body have raised concern among the scientific community as the knowledge about human exposure is still very limited and their impact on health is not well-understood yet. In this review article, we briefly cover the reports evidencing MP detection within the human body, e.g., stool, placenta, lungs, liver, sputum, breast milk, and blood. A concise synopsis of sample preparation and analysis of such human matrices is also provided. This article also presents a summary of the effect of MPs on human cell lines and human health.

Study on the binding of polystyrene microplastics with superoxide dismutase at the molecular level by multi-spectroscopy methods

Microplastics are harmful pollutants that widely exist worldwide and pose a severe threat to all types of organisms. The effects of polystyrene microplastics (PS-MPs) on organisms have been extensively studied, but the interaction mechanism between PS-MPs and superoxide dismutase (SOD) at the molecular level has not been reported yet. Therefore, based on multiple spectroscopic methods and enzyme activity measurements, the molecular mechanism of the interaction between PS-MPs and SOD was investigated. The multispectral results showed that the protein skeleton and secondary structure of SOD were altered by PS-MPs, resulting in decreased α-helix and β-sheet content. After PS-MPs exposure, fluorescence sensitization occurred, and micelles were formed, along with the enhanced hydrophobicity of aromatic amino acids in SOD. Moreover, the resonance light scattering (RLS) spectra result suggested that the PS-MPs and SOD combined to form a larger complex. Eventually, the activity of SOD was increased due to these structural changes, and the concentration of PS-MPs is positively correlated with SOD activity. This study can provide experimental support for studying the toxicological effects of PS-MPs.

The impact of modified polystyrene on lysozyme fibrillation studied by surface-enhanced Raman spectroscopy (SERS)

Nanoplastics could modulate the fibrillation of amyloid proteins. However, many chemical functional groups are adsorbed to change the interfacial chemistry of nanoplastics in the real world. Herein, this study aimed to investigate the effects of polystyrene (PS), carboxyl modified PS (PS-COOH), and amino modified PS (PS-NH₂) on the fibrillation of hen egg-white lysozyme (HEWL). Due to the differences in the interfacial chemistry, concentration was considered an essential factor. PS-NH₂ (10 μg/mL) could promote the fibrillation of HEWL similar to PS (50 μg/mL) and PS-COOH (50 μg/mL). Moreover, promoting the primary nucleation step of amyloid fibril formation was the primary reason. The differences in spatial conformation of HEWL were characterized by Fourier transform-infrared spectroscopy and surface enhanced Raman spectroscopy (SERS). Strikingly, a particular signal of SERS of HEWL incubated with PS-NH₂ at 1610 cm^-1 was found due to the interaction between amino group of PS-NH₂ and tryptophan (or tyrosine) of HEWL. Therefore, a new perspective was provided to understand the regulation of interfacial chemistry of nanoplastics on the fibrillation of amyloid proteins. Additionally, this study suggested that SERS could be a powerful method to investigate the interactions between proteins and nanoparticles.

Characterizing the binding interactions between virgin/aged microplastics and catalase in vitro

Microplastics (MPs) undergo physical, chemical, and biological aging in the environment, leading to changes in their physicochemical properties, affecting migration characteristics and toxicity. Oxidative stress effects induced by MPs in vivo have been extensively studied, but the toxicity difference between virgin and aged MPs and the interactions between antioxidant enzymes and MPs in vitro have not been reported yet. This study investigated the structural and functional changes of catalase (CAT) induced by virgin and aged PVC-MPs. It was shown that light irradiation aged the PVC-MPs, and the aging mechanism was photooxidation, resulting in a rough surface and appearing holes and pits. Because of the changes in physicochemical properties, aged MPs had more binding sites than virgin MPs. Fluorescence and synchronous fluorescence spectra results suggested that MPs quenched the endogenous fluorescence of CAT and interacted with tryptophane and tyrosine residues. The virgin MPs had no significant effect on the skeleton of CAT, while the skeleton and the polypeptide chains of CAT became loosened and unfolded after binding with the aged MPs. Moreover, the interactions of CAT with virgin/aged MPs increased the α-helix and decreased the β-sheet contents, destroyed the solvent shell, and resulted in a dispersion of CAT. Due to the large size, MPs cannot enter the interior of CAT and have no effects on the heme groups and activity of CAT. The interaction mechanism between MPs and CAT may be that MPs adsorb CAT to form the protein corona, and aged MPs had more binding sites. This study is the first comprehensive investigation of the effect of aging on the interaction between MPs and biomacromolecules and highlights the potential negative effects of MPs on antioxidant enzymes.

Spectroscopic investigations on the interaction between nano plastic and catalase on molecular level

As an emerging pollutant that is easily bonded with some functional proteins and the effects of their physiological expressions, nano plastics (NPs) have been widely detected in various environmental mediums, even in human blood. Compared to microplastics, less information on the interactions between NPs and proteins has been reported. Here, the interaction mechanism between common polystyrene nano plastics (PSNPs) and catalase (CAT) under two typical physiological conditions, pH 7.4 and 4.0, was investigated by UV-visible spectroscopy, circular dichroism (CD), and dynamic light scattering (DLS). Compared with the enhanced catalytic effects when increasing PSNPs at pH 7.4, a trend of initial inhibition and enhanced activity was observed at pH 4.0. Spectroscopic analysis and calculation results indicated that their binding was static, with only one binding site and stronger interactions under acidic conditions. UV-visible and CD spectra analysis demonstrated that the difference in enzymatic activity could be mainly attributed to the conformational alternation of CAT in the presence of PSNPs, which is obviously affected by solution chemistry. The change was also revealed by the hydrodynamic diameter and zeta potentials of the complexes supplied by DLS analysis. This study will help understand the health risks of nano plastic pollution and provide a theoretical basis for studying their toxicological effects.

Migration of microplastics from plastic packaging into foods and its potential threats on human health

Microplastics from food packaging material have risen in number and dispersion in the aquatic system, the terrestrial environment, and the atmosphere in recent decades. Microplastics are of particular concern due to their long-term durability in the environment, their great potential for releasing plastic monomers and additives/chemicals, and their vector-capacity for adsorbing or collecting other pollutants. Consumption of foods containing migrating monomers can lead to accumulation in the body and the build-up of monomers in the body can trigger cancer. The book chapter focuses the commercial plastic food packaging materials and describes their release mechanisms of microplastics from packaging into foods. To prevent the potential risk of microplastics migrated into food products, the factors influencing microplastic to the food products, e.g., high temperatures, ultraviolet and bacteria, have been discussed. Additionally, as many evidences shows that the microplastic components are toxic and carcinogenic, the potential threats and negative effects on human health have also been highlighted. Moreover, future trends is summarized to reduce the microplastic migration by enhancing public awareness as well as improving waste management.

Scrutinizing the interaction between metribuzin with glutathione reductase 2 from Arabidopsis thaliana: insight into the molecular toxicity in agriculture

As one of the triazine herbicides with widespread usage in agriculture, metribuzin exerted nonnegligible hazardous effects on plants via excessive accumulation of reactive oxygen species and destruction of antioxidant enzymes, but the underlying harmful mechanism of metribuzin-induced oxidative damage to plants has never been exploited. Here, Arabidopsis thaliana glutathione reductase 2 (AtGR2) was employed as the biomarker to evaluate the adverse impacts of metribuzin on plants. The fluorescence intensity of AtGR2 was decreased based on the static quenching mechanism with the prediction of a single binding site toward metribuzin, and the complex formation was presumed to be mainly impelled by hydrogen bonding and van der Waals forces from the negative ΔH and ΔS. In addition, the loosened and unfolded skeleton of AtGR2 along with the increased hydrophilicity around the tryptophan residues were investigated. Besides, the glutathione reductase activity of AtGR2 was also destroyed due to structural and conformational changes. At last, the severe inhibiting growth of Arabidopsis seedling roots was discovered under metribuzin exposure. Hence, the evaluation of the molecular interaction mechanism of AtGR2 with metribuzin will establish valuable assessments of the toxic effects of metribuzin on plants.

Multispectroscopy analysis of polystyrene nanoplastic interaction with diastase α-amylase

The digestive enzyme of plant are generally α-amylase. They functions enzyme that breakdown starch into maltose and sugars. This happens in the endosperm of the seed. Due to pollutants, this process get happened one of emergent xenobiotics are micro and nano plastics. This study involves the interaction 100 nm size of polystyrene nano plastic (PSNPs) on α-amylase. The hyperchromism of α-amylase - PSNPs conjugate's revealed that ground-state complex in a microenvironment. Fluorescence quenching happened when the concentration of PSNPs was increased. The Stern Volmer plot revealed binding constant (Ka) was 1.904 × 1019 M-1. S-1 while the quenching constant (Kq) was 1.036 × 1011 M-1, the blue shift of the peak showed static quenching. The binding constant was KA = 4.2 × 1012, the number of binding site on PSNPs for α-amylase was n = 1.12. The synchronous result showed a gradual reduction in the intensity of Trp residues because when the α-amylase interacts with PSNPs short-range π-π interaction happens around the Trp163 residues. The enzyme activity of α-amylase by 44 % and its IC50 value was found to be 100 µg/mL. The enzyme kinetics (Vmax) analysis showed the type of inhibition with and without PSNPs Vmax 769 and Vmax 303 µg/mL/min, uncompetitive inhibition respectively. The effect of PSNPs on the enzymatic activity of α-amylase showed structural alterations of the protein. Therefore the in vitro and in silico studies were shown evidence of interaction between α-amylase and PSNPs leads to conformational structural changes in α-amylase.

Food and human safety: the impact of microplastics

Plastic waste pollution is one of the biggest problems in the world today. The amount of plastic in the environment continues to increase, and human exposure to microplastic (MP) has become a reality. This subject has attracted the attention of the whole world. The MP problem has also been noticed by the scientific community. The term microplastic is mostly used to define synthetic material with a high polymer content that can have a size range from 0.1 to 5000 µm. This paper aims to characterize the routes of exposure to MP, define its pollution sources, and identify food types contaminated with plastics. This review addresses the current state of knowledge on this type of particles, with particular emphasis on their influence on human health. Adverse effects of MP depend on routes and sources of exposure. The most common route of exposure is believed to be the gastrointestinal tract. Sources of MP include fish, shellfish, water as well as tea, beer, wine, energy drinks, soft drinks, milk, salt, sugar, honey, poultry meat, fruits, and vegetables. Studies have shown that particles of PET, PE, PP, PS, PVC, PA, and PC are the most frequently found in food.

Plastic particles in medicine: A systematic review of exposure and effects to human health

Single-use plastics (SUPs) have become an essential constituent of our daily life. It is being exploited in numerous pharmaceutical and healthcare applications. Despite their advantages and widespread use in the pharma and medical sectors, the potential clinical problems of plastics, especially the release of micro-nanoplastics (MNPs) and additives from medical plastics (e.g. bags, containers, and administrative sets) and sorption of drugs remain understudied. Certainly, the MNPs are multifaceted stressors that cause detrimental effects to the ecosystem and human health. The origin and persistence of MNPs in pharmaceutical products, their administration to humans, endurance and possible health implication, translocation, and excretion have not been reviewed in detail. The prime focus of this article is to conduct a systematic review on the leaching of MNPs and additives from pharmaceutical containers/administrative sets and their interaction with the pharmaceutical constituents. This review also explores the primary and secondary routes of MNPs entry from healthcare plastic products and their potential health hazards to humans. Furthermore, the fate of plastic waste generated in hospitals, their disposal, and associated MNPs release to the environment, along with preventive, and alternative measures are discussed herein.

Microplastics in 48 wastewater treatment plants reveal regional differences in physical characteristics and shape-dependent removal in the transition zone between North and South China

This study investigated the physical characteristics and removal efficiency of microplastics in wastewater from regions with different climatic conditions and economic development levels. Microplastics with different shapes and sizes were analyzed from the influent and effluent of 48 wastewater treatment plants in three regions of Shaanxi Province (China). Results indicated that the abundance of microplastics in the influent samples was higher in the region with less regional water resources. However, the per capita microplastics emissions was higher in the region with higher economic development level. There were less fibers and more foams and beads in the more developed region. The removal efficiency of microplastics was related to their shape and size. Particularly, the removal efficiency showed a significant negative correlation with the percentage of foams, while it had a significant positive relationship with the proportions of films and fibers. The highest removal efficiency was obtained when the size of microplastics was ranged from 0.5 to 1.0 mm. This study suggests, compared to improving the removal efficiency of microplastics, that reducing the input at source is a more scientific and promising method.

Probing the potential toxicity by characterizing the binding mechanism of sodium dehydroacetate to human serum albumin

BACKGROUND

Sodium dehydroacetate (DHA-S) is a common food additive, which can combine with serum proteins in the plasma, but the interaction mechanism between DHA-S and human serum albumin (HSA) is unclear. In this study, multiple spectroscopy techniques, isothermal titration calorimetry (ITC), molecular docking and esterase activity test were employed to investigate the interaction mechanism of DHA-S and HSA.

RESULTS

A DHA-S-HSA complex was formed and the structure of HSA were altered by DHA-S. Since DHA-S changed the tight structure of the hydrophobic subdomain IIA where tryptophan (Trp) was placed, the hydrophobicity of the microenvironment of HSA was enhanced. With the addition of DHA-S, the skeleton structure of HSA became loose and the solvent shell on the HSA surface was destroyed. DHA-S altered the secondary structure of HSA, resulting in the decreased α-helix and increased β-sheet contents. The interaction was exothermic and spontaneous driven by van der Waals and hydrogen bonding. DHA-S inhibited the esterase activity of HSA. Molecular docking demonstrated that the binding site of DHA-S on HSA located at the cavity of subdomains IIA and IIIA, but the amino acids related to esterase activity of HSA were not in the binding pocket, indicating that the mechanism by which DHA-S inhibited HSA esterase activity was the change in protein structure.

CONCLUSION

This study illustrated that DHA-S interacted with HSA and the structure and function of HSA were affected by DHA-S. This research could help to understand the toxicity of DHA-S and provide basic data for safe use of food additives. © 2021 Society of Chemical Industry.

Nanoplastics alter the conformation and activity of human serum albumin

Nanoplastics finds its presence in most of the consumer products. Their chance of coming in contact with human cells and components is rampant. This study focuses on the interaction of polystyrene nanoplastics (PSNPs) with human serum albumin (HSA), ultimately causing structural and functional properties of the protein. Fluorescence and UV-Visible spectroscopic studies reported that PSNPs form a spontaneous ground-state complex with HSA, by hydrogen bonding, van der waal's, and hydrophobic force of attraction. This causes changes in the environment around major aromatic amino acids, especially tryptophan-214, which has a strong affinity with PSNPs. Further docking analysis confirmed hydrophobic interactions between PSNPs and aromatic amino acids in subdomain IIA of HSA. A shift in amide bands in HSA, as determined by FTIR analysis confirmed the disturbances in its secondary structure followed by reordering which will lead to the unfolding of HSA. Besides, PSNPs reduce the esterase activity of HSA by competitive inhibition. This molecular-level information such as binding energy, binding site, binding forces, reversible or irreversible binding, and structural changes of protein will shed light on the extent of toxicity in humans. This study will emphasize the urgent need for regulation of the use of nanoplastics (NPs) in consumer products, as well as the need for more research to determine the fate of NPs in the biological system.

Lysozyme amyloid fibril: Regulation, application, hazard analysis, and future perspectives

Self-assembly of misfolded proteins into ordered fibrillar aggregates known as amyloid results in various human diseases. However, more and more proteins, whether in human body or in food, have been found to be able to form amyloid fibrils with in-depth researches. As a model protein for amyloid research, lysozyme has always been the focus of research in various fields. Firstly, the formation mechanisms of amyloid fibrils are discussed concisely. Researches on the regulation of lysozyme amyloid fibrils are helpful to find suitable therapeutic drugs and unfriendly substances. And this review article summarizes a number of exogenous substances including small molecules, nanoparticles, macromolecules, and polymers. Small molecules are mainly connected to lysozyme through hydrophobic interaction, electrostatic interaction, π-π interaction, van der Waals force and hydrogen bond. Nanoparticles inhibit the formation of amyloid fibers by stabilizing lysozyme and fixing β-sheet. Besides, the applications of lysozyme amyloid fibrils in food-related fields are considered furtherly due to outstanding physical and mechanical properties. Nevertheless, the potential health threats are still worthy of our attention. Finally, we also give suggestions and opinions on the future research direction of lysozyme amyloid fibrils.

Time to Safeguard the Future Generations from the Omnipresent Microplastics

Microplastics (MPs) as a ubiquitous environmental pollutant have drawn growing attention, and it is concerning that children are more sensitive to MPs than adults. Unfortunately, information about the link between children and MPs is insufficient. Therefore, we review the sources and exposure routes of children to MPs and collect evidence for the potential risks. Children can ingest and/or inhale MPs derived from various foodstuffs and plastic products. Despite the limited knowledge on the toxicity to humans, current studies have proved the accumulation and translocation of MPs in different tissues and organs. Main damages including cytotoxicity, neurotoxicity, and immunotoxicity can be caused by pristine polymers and/or co-contaminants. There is much more to be understood about MPs, especially their health effects, and this study has made it clear that it is time to protect our future generations from the threat of MPs.

Spatial distribution of microplastic concentration around landfill sites and its potential risk on groundwater

Plastic plays a major role in today's human life; moreover, it becomes a part of our life, yet it is a most challenging threat for the freshwater ecosystems in the future. The present study identifies, characterizes, and quantifies the microplastics in groundwater samples around Perungudi and Kodungaiyur municipal solid waste dumpsites in South India. To evaluate and assess the microplastic abundance, characteristics (composite, size, colour, shape, and surface morphology), detection methods of plastic particles, and potential risk factors from the absorption of microplastic in groundwater. Further, the microplastic particle classification was performed using LB-340 Zoom Stereo Microscope with LED Illumination, ATR-FTIR fitted with SEM with EDX analyzer. The groundwater samples (n = 20) were found contaminated with microplastic particles in the range of 2-80 items/L with coloured particles, white (38%), black (27%), green (8%), red (18%), blue (6%), and yellow (2%). The polymer type was found to occur in the following order: nylon (70%), pellets (18%), foam (6%), fragments (3%), fibers/PVC (2%), and polythene (1%). In both sampling sites, 90% of microplastics are derived from the buried plastics and waste fragmentation which are predominantly of polypropylene (PP), polystyrene (PS). Micro and nano plastics abundance in groundwater is of paramount importance as it has a major impact on human health. This study throws light on the characteristics and quantification of the microplastics in groundwater that initiates further research by which microplastics enter into the environment.

Comprehensive insights into the interactions of dicyclohexyl phthalate and its metabolite to human serum albumin

Phthalate esters (PAEs) are a type of persistent organic pollutants and have received widespread concerns due to their adverse effects on human health. Dicyclohexyl phthalate (DCHP) and its metabolite monocyclohexyl phthalate (MCHP) were selected to explore the mechanism for interaction of PAEs with human serum albumin (HSA) through molecular docking and several spectroscopic techniques. The results showed that DCHP/MCHP can spontaneously occupy site I to form a binary complex with HSA, and DCHP exhibited higher binding affinity to HSA than MCHP. At 298 K, the binding constants (K_b) of DCHP and MCHP to HSA were 24.82 × 10⁴ and 1.04 × 10⁴ M^-1, respectively. Hydrogen bonds and van der Waals forces were the major driving forces in DCHP/MCHP-HSA complex. The presence of DCHP/MCHP induced the secondary structure changes in HSA, and the pi electrons of the benzene ring skeleton of DCHP/MCHP played a key role in this binding processes. Exposure of DCHP/MCHP to TM4 cells revealed that interactions between PAEs and serum albumin can affect their cytotoxicity; DCHP showed higher toxicity than MCHP. The binding affinity of PAEs with HSA may be a valuable parameter for rapid assessment of their toxicity to organisms.