Types Of Polymers Research Articles

Comparative evaluation of the impacts of different microplastics on greenhouse gas emissions, microbial community structure, and ecosystem multifunctionality in paddy soil

Although the increasing accumulation of microplastics (MPs) in terrestrial soil ecosystems has aroused worldwide concern, research remains limited on their potential impacts on soil processes and ecosystem functionality. Here, through a 41-day microcosm experiment, we found that polylactic acid (PLA), low-density polyethylene (LDPE), and polypropylene (PP) MPs consistently increased soil carbon nutrients and pH but had varying effects on soil nitrogen nutrients and the chemodiversity of dissolved organic matter (DOM). Different treatments led to notable shifts in the α-diversity and composition of soil microbial community, with phyla Proteobacteria and Ascomycota consistently enriched by MPs regardless of polymer type. The emissions of CO2 and N2O were suppressed by MPs in most cases, which in combination led to a decline in global warming potential. LDPE and 1 – 1.5% of PLA MPs significantly improved the multifunctionality of the soil ecosystem, while PP and 0.5% of PLA MPs exerted an opposite effect. Soil total organic carbon, pH, DOM molecular mass and condensation degree, and CO2 emissions were identified as the most important variables for predicting soil ecosystem multifunctionality. Results of this study can extend the current understanding of the impacts of MPs on soil biogeochemical cycling and ecosystem functionality. Environmental ImplicationSoils are the largest recipient of MPs. Due to their diverse origins, MPs in the soil are typically present in different polymer types, shapes, and concentrations, which may induce complex impacts on soil ecosystem. This study highlighted that polymer types and concentrations were two important factors influencing the specific impacts of MPs on soil carbon and nitrogen turnover, microbial community composition, and ecosystem multifunctionality. Biodegradable MPs can also profoundly affect soil processes and functionality, raising questions about their ecological benefits. Results of this study can improve the current understanding of the ecological risks of MPs contamination in the soil.

Synthesis and Characterization of Cu<sub>2</sub>O/ CuO Quantum Dots as Photocatalyst for Lignin Depolymerization via Reactive Oxygen Species: A Preliminary Study

Lignin is a type of polymer with diverse functional groups that can be transformed into biofuels and various high-value chemicals. By utilizing light energy and operating at low temperatures, photocatalysis via Reactive Oxygen Species (ROS) becomes a promising strategy to develop further. However, the revelation of photocatalyst mechanisms in ROS production to improve the efficiency and effectiveness of lignin transformation is still limited. This study aims to determine the effect of Cu2O/CuO quantum dots (QDs) concentration in the photocatalyst system on lignin depolymerization via ROS. The wet chemical method was used to synthesize Cu2O/CuO QDs. The property determination of absorbance, crystallinity, and particle morphology is characterized using uv-vis, X-ray diffraction (XRD), and Transmission Electron Microscope (TEM) instrument. The ROS production was measured using a UV-vis instrument by varying the Cu2O/CuO QDs concentration (1, 3, and 5 μM). The depolymerization sign was observed using a Fourier-Transform Infrared Spectroscopy (FTIR) instrument. The result shows that the synthesized material has a Cu2O/CuO phase with an average particle size of 8 nm and a band gap value of 2.35 eV. The optimum ROS production activity was achieved at the Cu2O/CuO QDs 3 μM concentration, reaching ten mM/sec. The FTIR result also confirms that the functional group transformation occurred. Overall, this study provides brief insight for further optimization of the lignin depolymerization photocatalysis process.

In-vivo Evaluation Methods for Preparation of Ophthalmic In-situ Gel

The eye is a vital component of the human sensory system, but various things can pose a threat to its cleanliness and well-being. An in-situ ophthalmic gel is one of the preparations developed to optimize the pharmacological activity in the eye. This formulation is intended to extend the drug's duration in the eye. An assessment is necessary to guarantee its occurrence and mitigate any adverse repercussions. The literature search conducted in this evaluation focused on an in-vivo study, enabling the collection of various pharmacokinetic data, including Cmax, Tmax, area under curve (AUC), and mean residence time (MRT). The polymer is an essential element in this inquiry, so the selection must be accurate according to the results of the literature review. The most effective method is high-performance liquid chromatography (HPLC), and the most effective polymer is a composite polymer formed by combining different types of polymers, such as Pluronic F127 and carbopol, pectin and thiolate, poloxamer and carbopol, and gellan gum and hydroxyethylcellulose. Aside from the polymer mixture, the poloxamer solution has the potential to produce highly positive results.

Monitoring of contamination by microplastics on sandy beaches at Vulcano Island (Sicily, Italy) by hyperspectral imaging.

In this work, the monitoring and characterization of large microplastics (1-5mm) collected from sandy beaches of Vulcano Island (Aeolian Islands, Sicily, Italy) were carried out for the first time. Microplastics were sampled from two beaches, "Gelso" and "Sabbie Nere," in three different time periods. The following characteristics of microplastic samples were assessed: quantity, distribution, categories, color, polymer type, size, and shape parameters. The polymers were identified using hyperspectral imaging, whereas an automatic image analysis approach was employed to determine microplastics' morphological and morphometrical attributes. Finally, the microplastic diversity integrated index was computed to obtain information on the potential emission sources of microplastics. It was found that the concentration of microplastics varies from 0.27 particles/kg_dw to 1.35 particles/kg_dw with fragment being the main collected category, with minor amount of pellet, foam, film, and filament. The predominant color of microplastics was by far white, followed by blue and yellow. The identified polymers were polyethylene and polypropylene followed by expanded polystyrene, polyamide, polystyrene, and polyethylene terephthalate. The morphological and morphometrical characterization highlighted a large variability for most size and shape parameters. Finally, the Microplastics Diversity Integrated Index results showed average indices compared to the literature, with higher values for the "Gelso" site (0.656), indicating a higher heterogeneity of sources, with respect to "Sabbie Nere" beach (0.530).

Nanosponges as a Drug Delivery System: Methods, Characteristics and Applications

Nanosponges, which are crosslinked polymer nanometers in sized used for drug transport, have a unique three-dimensional appearance. Their versatility lies in their ability to accommodate drugs of various sizes. The research approach, polymer type, and drug content determine the diversity of nanosponges. Nanosponges excel as delivery systems due to their capacity for controlled and targeted drug release. They offer the flexibility to regulate the duration of drug action and residence time. Their biodegradable composition ensures low toxicity and safe usage. Available voids, along with the size of the test molecule, play a crucial role in the efficiency of encapsulation. Nanosponges exhibit numerous applications such as cancer treatment, transportation of enzymes and biocatalysts, oxygen, modification of drug solubility, and immobilization of enzymes. This study emphasizes the preparation method, characterization, influencing factors, drug loading, recent advancements, and patents in the field of nanosponges.

Comparison of oven drying and freeze drying methods for the production of fast melt films containing quetiapine fumarate

Background Quetiapine fumarate (QTP) is commonly prescribed for schizophrenic patient, typically available in tablet or oral suspension form, presenting challenges such as administration difficulties, fear of choking and distaste for its bitter taste. Fast melt films (FMF) offer an alternative dosage form with a simple development process, ease of administration and rapid drug absorption and action onset. Objective This study aims to prepare FMF with different formulations using solvent casting methods and to compare the effects of different drying methods, including oven drying and freeze drying, on the properties of the films. Methods Various formulations were created by manipulating polymer types (starch, hydroxypropyl methylcellulose (HPMC) and guar gum) at different concentrations, along with fixed concentrations of QTP and other excipients. Characterisation tests including surface morphology, weight, thickness, pH, tensile strength, elongation length, Young’s modulus, folding endurance and disintegration time were conducted. The optimal FMF formulation was identified and further evaluated for moisture and drug content, dissolution behaviour, accelerated stability, X-ray diffraction (XRD), and palatability. Results FMF containing 10 mg guar gum/film developed using oven drying emerged as the optimum choice, exhibiting desirable film appearance, ultra-thin thickness (0.453 ± 0.002 mm), appropriate pH for oral intake (pH 5.0), optimal moisture content of 11.810%, rapid disintegration (52.67 ± 1.53 seconds), high flexibility (folding endurance > 300 times) and lower Young’s modulus (1.308 ± 0.214). Conclusion Oven drying method has been proven to be favourable for developing FMF containing QTP, meeting all testing criteria and providing an alternative option for QTP prescription.

Investigation of Gnetum Gnemon and Ramie Natural Fiber on the Mechanical Properties of Composites with the Combination of Aramid and Carbon Fiber as Reinforcement for Military Personnel Applications

Every equipment infrastructure in a TNI unit will be needed to support an operation in the defence system to maintain the integrity of the Unitary State of the Republic of Indonesia. Personal protective equipment is needed for a war operation’s safety or continuity. Protective components made from composite fibers have the advantage of being resistant to corrosion caused by the environment. The natural and carbon fibers will be mixed/reinforced with epoxy resin to become composite materials. This study aims to identify Gnetum Gnemon fiber composites with carbon fiber and aramid fiber to determine the mechanical properties of the composite material resulting from a collision. Natural fiber Gnetum gnemon has not been widely studied as a reinforcing material for polymer composites. Gnetum gnemon fiber chemical composition is hemicellulose approx. 25%, 40% alpha cellulose, 10% lignin and 3-5% benzene extractive. Its density is quite light, 1.2087 g/cm³ - 1.8069 g/cm³. Because this fiber has a continuous fiber structure and a strong natural weave, its use is still minimal. Special treatment such as alkali treatment on Gnetum gnemon, can increase the strength of natural fibers. Due to its exceptional mechanical properties, Kevlar or aramid fibre are extensively used in industrial and military applications. The aramid fiber exhibited a transversely anisotropic nature in a small strain range, with its stress-strain behavior as linear and elastic. The anisotropic nature of the aramid fiber was due to its high tensile-to-shear modulus ratio. The high strength and modulus were also found to be scattered due to the larger distribution of defects in the longer fiber. Epoxy resin is a type of polymer characterized often by one or more epoxide functional groups, with at least one of the epoxide functional groups acting as a monomer and terminal unit of the polymer within the structural chain.

Characteristics, drivers and ecological risk assessment of microplastics in the surface water of urban rivers in Guangdong-Hong Kong-Macao Greater Bay Area cities - A case study of Dongguan city

In the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), microplastic pollution in urban rivers is a prominent problem due to the developed economy and high industrial intensity. Using the Xiaohai River, Hanxi River and Dongguan Canal in Dongguan City, an important node city in the GBA, as an example, microplastic characteristics, drivers and ecological risks in the surface water of three rivers were investigated. Results showed that the average abundance of rivers in the wet period (1646.22 ± 154.73 items/m3) was 4.7 times higher than that in the dry period (351.09 ± 34.2 items/m3). Microplastics were mainly in the form of fragments and fibers, with a size range of 30–500 μm, and appeared transparent with white color. The microplastic polymer types PE, PP, PET and PA accounted for more than 70%. There are large differences in the characteristics of microplastic pollution during different hydrological periods. Redundancy analysis showed that the distribution of plastics, chemical materials, packaging and printing industries along the rivers dominated the differences in microplastic abundance. The electronic information industry contributed most to the composition of microplastic polymer types. The polymer hazard index, pollution load index, and potential ecological risk index for rivers indicate a medium-high risk classification or higher. Therefore, the industrial layout along the urban rivers should be rationalized, the disposal of microplastics in wastewater should be increased, and the use of green plastic products should be promoted. This study provides support for the management of microplastic pollution in urban surface water in the GBA.

Formulation and evaluation of medicated lozenges containing the solid dispersion of Clotrimazole /PEG 6000 for the treatment of oral candidiasis

The study aimed to formulate Clotrimazole (CLM) as solid dispersion medicated lozenges with enhanced dissolution for treating oropharyngeal candidiasis. They are suitable for many patients and easy to administer. The study used the solvent evaporation method to prepare solid dispersions of CLM using polyethylene glycol 6000 and polyvinyl pyrrolidone at different drug-to-carrier weight ratios. The study found that PEG 6000, when used at a 1:1 weight ratio, significantly improved the dissolution of CLM. The results of the FTIR studies showed that the drug was dispersed within PEG 6000, and there was no drug interaction with the excipients used in medicated lozenge formulations. A 32-factorial design was used to develop, optimize, and evaluate nine formulations of the solid dispersion of CLM/PEG 6000 medicated lozenges for improved therapeutic outcomes. We fabricated the lozenges using biocompatible polymeric gelling agents (chitosan, methyl cellulose, and sodium alginate) at three different levels (0.5, 1, and 1.5%). All the medicated lozenges were uniform in weight and drug content within USP limits, with complete drug release rates ranging from 10–20 minutes for chitosan and sodium alginate formulations, compared to 60 minutes for methyl cellulose. The results showed that the type of polymer and its concentration significantly impacted drug release. The optimized formulation, F-3, containing 1.5% CH, exhibited a drug release of 100.83% ±0.68 at the end of 10 minutes. It demonstrated significant antifungal activity against Candida albicans (p < 0.05), making it suitable for drug delivery in the oral cavity.

Primary risk assessment of microplastic pollution in spineless cuttlefish (Sepiella inermis) from the North-East Bay of Bengal: A tissue-based analysis

Microplastic pollution has a significant threat to marine ecosystems, yet its impact on spineless cuttlefish (Sepiella inermis) remains under-researched. This study aims to address this gap by analysing microplastic contamination in Sepiella inermis from the North-East Bay of Bengal. This species is widely consumed and transported globally as food, thus holding significant health concerns. A total of 40 adult female cuttlefish were collected from two sampling sites (18°36′31.35″N 87°48′10.63″E and 15°43′35.37″N 88°12′07.01″E) in the Bay of Bengal. Tissue samples from tentacles, gut, and nidamental glands were analysed for microplastic content, alongside sediment and surface water samples. Parameters such as microplastic abundance, size, shape, and colour were recorded. The average abundance of microplastic particles was measured at 2.003 particles per gram in tentacle tissue, 2.31 particles per gram in gut tissue, and 0.99 particles per gram in nidamental gland tissue. The gut tissue exhibited the highest abundance of microplastics per gram. Chemical characterization using FT-IR and confocal Raman spectroscopy identified 11 types of microplastic polymers. Of the 11 types of plastic polymers identified, PVC was the most prevalent, accounting for 17.64 % of the microplastics found across all tissues. PVC microplastics can cause significant harm to marine life and human health by accumulating in the food chain and releasing harmful chemicals like phthalates, which can lead to endocrine disruption. ABS, PET, PP, PE, and PA microplastic polymers are highly persistent in environment, leading to long-term pollution in oceans. When ingested by marine organisms, they can disrupt entire ecosystems. In humans, the accumulation of these microplastics can impair the immune system and contribute to chronic diseases. The Pollution Load Index (PLI) was calculated for each tissue type, revealing that gut tissue is more prone to microplastic pollution compared to the nidamental gland and tentacles. The average PLI per gram of gut tissue was 2.26, which was significantly higher than 1, indicating substantial pollution. This research highlights the urgent need for comprehensive strategies to mitigate microplastic pollution, given the potential health risks associated with the consumption of contaminated marine species.

A novel mucoadhesive film containing probiotic extract for oral candidiasis treatment: Formulation and antifungal evaluation

Probiotic strains offer a novel and potentially effective approach to treat oral candidiasis. Buccal mucoadhesive films have attracted considerable attention in recent years due to their unique ability to adhere and persist on the oral mucosa, while gradually releasing their encapsulated drug content. Therefore, the aim of the study was to develop mucoadhesive films containing probiotic extract for treatment of oral candidiasis. Mucoadhesive films were fabricated with hydrophilic polymers, such as polyvinyl alcohol (PVA) and hydroxy propyl methyl cellulose (HPMC). Then, films were evaluated regarding their thickness, pH, tensile strength and elongation, swelling, in vitro release and antifungal activity. The type of polymer used had an impact on the mechanical properties, swelling and release of the films. Films prepared using PVA showed significantly higher tensile strength and elongation at break values compared to those prepared using HPMC. However, swelling index increased with enhancing HPMC concentration in the films. The release of probiotic extract from the film prepared with HPMC occurred slowly. Based on these results, films containing 54 % HPMC and 26 % PVA were selected as optimal formulation. Moreover, it was found that optimal film containing probiotic extract could inhibit the growth of Candida albicans. Regarding to the obtained results, probiotic oral adhesive mucoadhesive films can be considered as a promising alternative to traditional methods in the treatment of candidiasis.

Fate and effects of an environmentally relevant mixture of microplastics in simple freshwater microcosms

Most studies assessing the effects of microplastics (MPs) on freshwater ecosystems use reference materials of a certain size, shape, and polymer type. However, in the environment, aquatic organisms are exposed to a mixture of different polymers with different sizes and shapes, resulting in different bioaccessible fractions and effects. This study assesses the fate and effects of an environmentally relevant mixture of high-density polyethylene (HDPE) fragments, polypropylene (PP) fragments, and polyester (PES) fibres in indoor freshwater microcosms over 28 days. The MP mixture contained common polymers found in freshwater ecosystems, had a size range between 50 and 3887 µm, and was artificially aged using a mercury lamp. The invertebrate species included in the microcosms, Lymnea stagnalis (snail) and Lumbriculus variegatus (worm), were exposed to four MP concentrations: 0.01, 0.05, 0.1 and 1 % of sediment dry weight. MPs fate was assessed by performing a balance of the MPs in the surface water, water column, and sediment after a stabilization period and at the end of the experiment. Sedimentation rates per day were calculated (2.13 % for PES, 1.46 % for HDPE, 1.87 % for PP). The maximum size of MPs taken up by the two species was determined and compared to the added mixture and their mouth size. The size range taken up by L. variegatus was smaller than L. stagnalis and significantly different from the size range in the added mixture. The No Observed Effect Concentrations (NOECs) for the reproduction factor of L. variegatus and the number of egg clutches produced by L. stagnalis were 0.01 % and 0.1 % sediment dry weight, respectively. The EC10 and EC50 for the same endpoint for L. stagnalis were 0.25 % and 0.52 %, respectively. This study shows that current MP exposure levels in freshwater sediments can result in sub-lethal effects on aquatic organisms, highlighting the importance of testing MP mixtures.

Development and Evaluation of Oromucosal Spray Formulation Containing Plant-Derived Compounds for the Treatment of Infectious and Inflammatory Diseases of the Oral Cavity.

According to data in the literature, natural products and essential oils are often used in dental practice. To develop a new oromucosal spray for the treatment of infectious and inflammatory diseases of the oral cavity, clove CO2 extract and essential oils of lavender and grapefruit were used as active pharmaceutical ingredients. Clove extract was obtained by the method of subcritical extraction from various raw materials, the choice of which was based on the yield of the CO2 extract and the study of its phytochemical and microbiological properties. Based on the results of microscopic and diffraction analyses, the rational time of ultrasonic exposure for the emulsion of active pharmaceutical ingredients was established. Mucoadhesive polymers were used as stabilizers of the two-phase system and prolongators. This article discusses the impact of the type and concentration of mucoadhesive polymers on the stability of the emulsion system; the viscous, textural, adhesive, and film characteristics of oromucosal spray; and the parameters determining sprayability.

Biofilms on urban aquatic plastic pollution as a reservoir for pathogenic yeasts

ABSTRACT Pollution of aquatic environments is a concern and poses a health risk to aquatic and terrestrial life. Plastic pollution acts as surfaces to which microorganisms adhere, forming a community known as the plastisphere. Studies investigating the bacterial diversity of the plastisphere are plentiful, but less is known about the fungal communities, especially yeasts, within these biofilms. Given the increasingly recognised threat of yeast infections, it is important to investigate the environmental presence of potential pathogenic yeasts on possible vectors that may contribute to their distribution. In this study, the fungal diversity of the plastisphere of various types of plastic polymers collected from an urban freshwater source was analysed, and possibly pathogenic yeast strains were identified. Isolates were also tested for susceptibility to the antifungal, fluconazole. Microscopic analysis shed light on the overall diversity found in the plastisphere, while metagenomic data revealed that fungal plastisphere communities are dominated by the phylum Ascomycota. Both metagenomic and culture-dependant analysis revealed the presence of possibly pathogenic yeast in the genera Candida (some with low fluconazole susceptibility) and Exophiala. This highlights possibilities that the plastisphere may harbour pathogenic yeasts and could contribute to their distribution in the environment and transmission between the environment and humans.

Impact of seasonal changes and environmental conditions on suspended and inhalable microplastics in urban air

Microplastics (MPs) are ubiquitous environmental pollutants extensively detected in atmospheric environments. Airborne MPs have raised concerns due to their transport and potential health risks of inhalation exposure. However, the factors influencing airborne MPs, particularly their concentrations and shapes suspended in urban air, remain unclear. We investigated MPs in total suspension particles with one-year measurements in Taipei City and identified their features using Nile Red staining combined with fluorescence microscopy and micro-Fourier transform infrared (μFTIR) spectroscopy. This study quantified the mean number concentration of total MPs as approximately 6.0 #/m³. We observed that MP abundance varied seasonally, with higher levels in the warm season than in the cold. A similar trend was noted for polymer types. Fragment-like MPs were the predominant shape, mainly found in polystyrene (PS), polyethylene (PE), and polypropylene (PP), while fibrous MPs, detected mostly as polyethylene terephthalate (PET) and polyamide (PA), were primarily observed at sizes greater than 300 μm. Both fiber and fragment-like MPs were positively associated with particle mass concentration, temperature, ultraviolet (UV) index, and wind speed, but negatively correlated with relative humidity and rainfall. Fibrous MPs were more affected by environmental factors than fragment-like MPs. Meteorological changes significantly influenced suspended MPs more than human activity within the city.

Polymer Single-Chain Nanoparticles: Shaping Solid Surfactants.

Polymer single-chain nanoparticles (SCNPs) have found a wide range of applications spanning catalysts, sensors and nanomedicine. The generation of structured SCNPs from star-shaped polymers with diverse architectures and functionalities affords a new avenue to expand the emerging research area. The large-scale synthesis of structured SCNPs is described by the electrostatics-mediated intramolecular crosslinking of three types of 3-armed star-shaped polymers (T-P4VP, T-PS-b-P4VP, and T-P4VP-b-PS), whose configuration is tunable from spherical to cage-shaped to dumbbell-shaped and star-shaped. The structured SCNPs are amphiphilic and can be used as solid surfactants to stabilize different types of emulsions.

Microplastic pollution in tropical coral reef ecosystems from the coastal South China Sea and their impacts on corals in situ

Coral reefs possess extremely high ecological value in tropical and subtropical waters worldwide. Microplastics as emerging and pervasive pollutants pose a great threat to the health of coral ecosystems. However, in situ studies on microplastics pollution and its impacts in coral ecosystems globally are limited. The occurrence characteristics of microplastics in the environment mediums and reef-dwelling organisms were investigated in coral reef areas from the southern Hainan Island, and the impacts of microplastics on corals in situ were evaluated in this study. Average microplastics abundance was 9.48 items L-1 in seawater, 190.00 items kg-1 in sediment, 0.36 items g-1 in coral, 1.50 items g-1 in shellfish, 0.48 items g-1 in fish gill, and 1.71 items g-1 in fish gastrointestinal tract. The prevalent microplastics in the above samples were characterized as being less than 1000 µm in size, fibrous, and transparent, with predominant polymer types as polyethylene terephthalate, polypropylene, polyethylene, and rayon. The microplastic enrichment capacity of different corals varied (Pocillopora >Acropora >Sinularia). Notably, microplastics were more abundant on the surface of corals compared to their interiors, with distinct characteristics observed, including larger-sized (>500 µm) and fiber-shaped polyethylene terephthalate microplastics on the surface and smaller-sized (20–200 µm) fragmented polyethylene microplastics within coral interiors. Furthermore, the investigation showed species-specific impacts of microplastics on corals in situ, including photosynthetic activity of photosymbionts and antioxidant and immune activities of corals. Furthermore, the ecological risks of microplastics were minor across most environmental media in the studied areas, with exceptions in the bottom seawater and surface sediment of YLW, which exhibited extreme and medium risk levels, respectively. Coral risk levels were generally medium, except for dangerous levels in DDH and high levels in LHT. The potential sources of microplastics in the marginal reefs of southern Hainan Island were primarily tourism, residential, and fishing activities.

3D printed oxygen gas sensor with a Pt-nanoparticles decorated N-doped carbon catalyst and an amine-polymer composited ionic liquid gel electrolyte

A 3D-printed electrochemical oxygen gas sensor was developed using a Pt nanoparticle-decorated N-doped carbon (PtNC) catalyst and an ionic liquid gel electrolyte incorporated with polyethyleneimine. At first, N-doped carbon particles were synthesized hydrothermally, followed by the decoration of a tiny amount of Pt nanoparticles using a microwave reactor. The working electrode was printed with a composite of high-impact polystyrene (HIPs), graphite powder (Gr), and a PtNC catalyst (HIPs/Gr/PtNC), then counter and reference electrodes were separately printed without the PtNC catalyst. The sensing materials were characterized using various analytical methods, including SEM, XPS, Raman, ICP-AES, CV, and EIS. Prior to detecting oxygen gas, the 3D sensor surface was pretreated with potential cycling in an acidic solution. Additionally, a composite gel electrolyte was prepared by incorporating polyethyleneimine into an ionic liquid, which was then coated onto the sensor surface to enhance sensitivity and ensure long-term stability. The analytical parameters using the final sensor were optimized in terms of Pt contents, 3D-printing polymer type, and ionic liquid gel concentration. The amperometric measurements demonstrated a wide dynamic range from 0.1 % to 100 % with the detection limit of 0.13 ± 0.05 % at a 90 % response time of 3.6 ± 0.4 s. To validate the reliability of the proposed sensor, the measurement of O2 content was performed for room air and standard oxygen gas, revealing reliable and stable results for six months.

Complex microplastics significantly influence the assembly process of lake bacterial communities

Environmental microplastics (MPs) vary in abundance, shape, size, color, and polymer type in freshwater ecosystems, yet their impact on bacterial community assembly in natural lakes is unclear. Here, we examined MPs and bacterial compositions in water and sediments of Taihu Lake, China, to reveal the influence of complex MPs on the bacterial community assembly. The results showed that the complexity index of MPs significantly influenced the turnover and nestedness components of bacterial communities. In the colder season, MP complexity was significantly correlated with the turnover componentin sediments (R2 = 0.19, P < 0.0001), with turnover increasing as MP complexity increased. Conversely, under warmer season, MP complexity was significantly correlated with turnover and nestedness components. Additionally, the interaction effect of environmental and MP factors affected almost all components of beta diversity, particularly in cold water and sediment, with impacts on nestedness of 0.17 and 0.12, respectively, and should thus not be ignored. Our findings indicate for the first time that complex MPs significantly influence the assembly of bacterial communities in lake systems. The impact varies across seasons and future warming may exacerbate this effect, rendering it more uncertain and complex.

Deciphering the cytotoxicity of micro- and nanoplastics in Caco-2 cells through meta-analysis and machine learning

Plastic pollution, driven by micro- and nanoplastics (MNPs), poses a major environmental threat, exposing humans through various routes. Despite human colorectal adenocarcinoma Caco-2 cells being used as an in vitro model for studying the intestinal epithelium, uncertainties linger about MNPs harming these cells and the factors influencing adverse effects. Addressing this lacuna, our study aimed to elucidate the pivotal MNP parameters influencing cytotoxicity in Caco-2 cells, employing meta-analysis and machine learning techniques for quantitative assessment. Initial scrutiny of 95 publications yielded 17 that met the inclusion criteria, generating a dataset of 320 data points. This dataset underwent meticulous stratification based on polymer type, exposure time, polymer size, MNP concentration, and biological assays utilised. Subsequent dose-response curve analysis revealed moderate correlations for selected subgroups, such as the (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) MTT biological assay and exposure time exceeding 24 h, with coefficient of determination (R2) values of 0.50 (p-value: 0.0065) and 0.60 (p-value: 0.0018) respectively. For the aforementioned two subgroups, the MNP concentrations surpassing 10 μg/mL led to diminished viability of Caco-2 cells. Notably, we observed challenges in employing meta-analysis to navigate this multidimensional MNP dataset. Leveraging a random forest model, we achieved improved predictive performance, with R2 values of 0.79 and a root mean square error (RMSE) of 0.14 for the prediction of the Log Response Ratio on the test set. Model interpretation indicated that size and concentration are the principal drivers influencing Caco-2 cell cytotoxicity. Additionally, the partial dependence plot illustrating the relationship between the size of MNPs and predicted cytotoxicity reveals a complex pattern. Our study provides crucial insights into the health impacts of plastic pollution, informing policymakers for targeted interventions, thus contributing to a comprehensive understanding of its human health consequences.