Detecting the release of plastic particles in packaged drinking water under simulated light irradiation using surface-enhanced Raman spectroscopy

Microplastics in drinking water: A review on methods, occurrence, sources, and potential risks assessment

Microplastics in drinking water captured widespread attention following reports of widespread detection around the world. Concerns have been raised about the potential adverse effects of microplastics in drinking water on human health. Given the widespread interest in this research topic, there is an urgent need to compile existing data and assess current knowledge. This paper provides a systematic review of studies on microplastics in drinking water, their evidence, key findings, knowledge gaps, and research needs. The data collected show that microplastics are widespread in drinking water, with large variations in reported concentrations. Standardized methodologies of sampling and analysis are urgently needed. There were more fibrous and fragmented microplastics, with the majority being <10 μm in size and composed of polyester, polyethylene, polypropylene, and polystyrene. Little attention has been paid to the color of microplastics. More research is needed to understand the occurrence and transfer of microplastics throughout the water supply chain and the treatment efficiency of drinking water treatment plants (DWTPs). Methods capable of analyzing microplastics <10 μm and nanoplastics are urgently needed. Potential ecological assessment models for microplastics currently in use need to be improved to take into account the complexity and specificity of microplastics.

Rapid detection of nanoplastics down to 20 nm in water by surface-enhanced raman spectroscopy

Plastic pollution represents a pressing global environmental issue, with microplastics (MPs) and nanoplastics (NPs) being ubiquitously found in both food and the environment. However, the investigation of NPs has been hampered by limited detection technologies, necessitating the development of advanced techniques. This study introduces a sol-based surface-enhanced Raman spectroscopy (SERS) approach for the swift detection of MPs and NPs in aqueous environment. By leveraging the aggregation effect between silver nanoparticles (Ag nanoparticles) and plastic particles, the plastic Raman signals is significantly enhanced, effectively lowering the detection limit. Utilizing Ag nanoparticles, plastic particles as small as 20 nm were detected in liquid samples, with a detection limit of 0.0005%. With the developed method, nanoplastic particles in seafood packaging samples were successfully tested, with concentration found to be at μg/L level. This method offers a rapid, economical, and convenient means of detecting and identifying MPs and NPs. The sensitivity of the method allows for capturing plastic signals within 2 min, making it valuable for aquatic environment contamination detection. SERS technology also holds promise for rapid plastic solution detection, potentially becoming a fast detection method for food safety.

Interaction and mechanistic studies of thiram and common microplastics in food and associated changes in hazard

Microplastics (MPs), an emerging pollutant in the environment and food, may adsorb other contaminants such as pesticide due to particles' properties. The adsorption behavior and their hazardous changes of four common types of MPs to thiram was investigated. The adsorption kinetics and isotherm models were fitted well using the pseudo-second-order model and the Langmuir model respectively, indicating forces such as van der Waals forces dominate, and the maximum adsorption capacity at pH values of 6-7 also indicates that electrostatic forces play a smaller role. The adsorption thermodynamic studies showed that the adsorption was a spontaneous and exothermic process. The decrease in the adsorption capacity as the concentration of MPs increases and more adsorption by aged MPs demonstrate that the adsorption process is related to the sites on the surface of MPs. Due to the influence of ionic strength, the adsorption capacity of MPs for thiram increases significantly when the adsorption process takes place in solutions with salinity or in orange and apple juices. The bioavailability of thiram adsorbed by PVC and PET increased significantly. This study highlights the strong role of MPs in food as carriers of pesticide residues in food systems and that the combined hazard should also be of concern.

Dark background-surface enhanced Raman spectroscopic detection of nanoplastics: Thermofluidic strategy

This study aims to develop a cost-effective and time-efficient method for detecting nanoplastics, which have recently garnered significant attention due to their potential harmful impact on the water environment (XiaoZhi, 2021; Gigault et al., 2021; Mitrano et al., 2021; Ferreira et al., 2019). Although several techniques are available to accumulate data on microplastics, there is currently no universally accepted analytical technique for detecting nanoplastics (Gigault et al., 2021; Mitrano et al., 2021; Mitrano et al., 2019; Cai et al., 2021a; Allen et al., 2022). In this study, we have developed a substrate that exhibits Surface-enhanced Raman scattering (SERS) (Zhou et al., 2021; Lv et al., 2020; Lê et al., 2021; Hu et al., 2022; Chang et al., 2022; Yang et al., 2022; Xu et al., 2020; Jeon et al., 2021; Lee and Fang, 2022; Vélez-Escamilla and Contreras-Torres, 2022; Liu et al., 2022; Xie et al., 2023) activity over a large area and a dark background in optical (darkfield mode) vision, enabling the detection of sparkling nanoplastics on the substrate. This darkfield-based strategy allows for the point-by-point detection of single nanoplastics, offering cost and time-saving advantages over other resource-intensive analytical techniques. Our findings reveal the presence of PP nanoplastics in commonly used laboratory equipment, individual PE nanoplastics from a hot water-contained commercial paper cup, and the first detection of natural nanoplastics in coastal seawater. We believe that this technique will have a universal application in establishing a global map of nanoplastics and advancing our understanding of the environmental life cycle of plastics.

Application of Infrared and Near-Infrared Microspectroscopy to Microplastic Human Exposure Measurements

Microplastic pollution is a global issue for the environment and human health. The potential for human exposure to microplastic through drinking water, dust, food, and air raises concern, since experimental in vitro and in vivo toxicology studies suggest there is a level of hazard associated with high microplastic concentrations. However, to infer the likelihood of hazards manifesting in the human population, a robust understanding of exposure concentrations is needed. Infrared and near-infrared microspectroscopies have routinely been used to analyze microplastic in different exposure matrices (air, dust, food, and water), with technological advances coupling multivariate and machine learning algorithms to spectral data. This focal point article will highlight the application of infrared and Raman modes of spectroscopy to detect, characterize, and quantify microplastic particles, with a focus on human exposure to microplastic. Methodologies and state-of-the-art approaches will be reported and potential confounding variables and challenges in microplastic analysis discussed. The article provides an up-to-date review of the literature on microplastic exposure measurement using (near) infrared spectroscopies as an analytical tool, highlighting the recent advances in this rapidly advancing field.

Imaging and identification of single nanoplastic particles and agglomerates

Pollution by nanoplastic is a growing environmental and health concern. Currently the extent of nanoplastic in the environment can only be cumbersomely and indirectly estimated but not measured. To be able to quantify the extent of the problem, detection methods that can identify nanoplastic particles that are smaller than 1 [Formula: see text]m are critically needed. Here, we employ surface-enhanced Raman scattering (SERS) to image and identify single nanoplastic particles down to 100 nm in size. We can differentiate between single particles and agglomerates and our method allows an improvement in detection speed of [Formula: see text] compared to state-of-the art surface-enhanced Raman imaging. Being able to resolve single particles allows to measure the SERS enhancement factor on individual nanoplastic particles instead of averaging over a concentration without spatial information. Our results thus contribute to the better understanding and employment of SERS for nanoplastic detection and present an important step for the development of future sensors.

Simulation and Characterization of Nanoplastic Dissolution under Different Food Consumption Scenarios

Understanding of the potential leaching of plastic particles, particularly nanoplastics (NPs), from food packaging is crucial in assessing the safety of the packaging materials. Therefore, the objective of this study was to investigate potential exposure risks by simulating the release of NPs from various plastic packaging materials, including polypropylene (PP), general casting polypropylene (GCPP) or metalized casting polypropylene (MCPP), polyethylene (PE), polyethylene terephthalate (PET), and polyphenylene sulfone (PPSU), under corresponding food consumption scenarios. Surface-enhanced Raman scattering (SERS) and scanning electron microscopy (SEM) were utilized to identify and characterize the NPs leached from plastic packaging. The presence of separated NPs was observed in PP groups subjected to 100 °C hot water, GCPP plastic sterilized at a high temperature (121 °C), and PE plastic soaked in 100 °C hot water, exhibited a distorted morphology and susceptibility to aggregation. The findings suggest that the frequent consumption of takeaway food, hot beverages served in disposable paper cups, and foods packaged with GCPP materials may elevate the risk of ingestion of NPs. This reminds us that food packaging can serve as an important avenue for human exposure to NPs, and the results can offer valuable insights for food safety management and the development of food packaging materials.

Insights into Anthropogenic Micro- and Nanoplastic Accumulation in Drinking Water Sources and Their Potential Effects on Human Health

Anthropogenic microplastics (MPs) and nanoplastics (NPs) are ubiquitous pollutants found in aquatic, food, soil and air environments. Recently, drinking water for human consumption has been considered a significant pathway for ingestion of such plastic pollutants. Most of the analytical methods developed for detection and identification of MPs have been established for particles with sizes > 10 μm, but new analytical approaches are required to identify NPs below 1 μm. This review aims to evaluate the most recent information on the release of MPs and NPs in water sources intended for human consumption, specifically tap water and commercial bottled water. The potential effects on human health of dermal exposure, inhalation, and ingestion of these particles were examined. Emerging technologies used to remove MPs and/or NPs from drinking water sources and their advantages and limitations were also assessed. The main findings showed that the MPs with sizes > 10 μm were completely removed from drinking water treatment plants (DWTPs). The smallest NP identified using pyrolysis-gas chromatography-mass spectrometry (Pyr-GC/MS) had a diameter of 58 nm. Contamination with MPs/NPs can occur during the distribution of tap water to consumers, as well as when opening and closing screw caps of bottled water or when using recycled plastic or glass bottles for drinking water. In conclusion, this comprehensive study emphasizes the importance of a unified approach to detect MPs and NPs in drinking water, as well as raising the awareness of regulators, policymakers and the public about the impact of these pollutants, which pose a human health risk.

Controllable preparation of mesoporous spike gold nanocrystals for surface-enhanced Raman spectroscopy detection of micro/nanoplastics in water

Microplastics and nanoplastics are emerging classes of environmental contaminants that pose significant threats to human health. In particular, small nanoplastics (<1 μm) have drawn considerable attention owing to their adverse effects on human health; for example, nanoplastics have been found in the placenta and blood. However, reliable detection techniques are lacking. In this study, we developed a fast detection method that combines membrane filtration technology and surface-enhanced Raman spectroscopy (SERS), which can simultaneously enrich and detect nanoplastics with sizes as small as 20 nm. First, we synthesized spiked gold nanocrystals (Au NCs), achieving a controlled preparation of thorns ranging from 25 nm to 200 nm and regulating the number of thorns. Subsequently, mesoporous spiked Au NCs were homogeneously deposited on a glass fiber filter membrane to form an Au film as a SERS sensor. The Au-film SERS sensor achieved in-situ enrichment and sensitive SERS detection of micro/nanoplastics in water. Additionally, it eliminated sample transfer and prevented the loss of small nanoplastics. Using the Au-film SERS sensor, we detected 20 nm to 10 μm standard polystyrene (PS) microspheres with a detection limit of 0.1 mg/L. We also realized the detection of 100 nm PS nanoplastics at the 0.1 mg/L level in tap water and rainwater. This sensor provides a potential tool for rapid and susceptible on-site detection of micro/nanoplastics, especially small-sized nanoplastics.

Advances in surface-enhanced Raman spectroscopy technology for detection of foodborne pathogens

Rapid control and prevention of diseases caused by foodborne pathogens is one of the existing food safety regulatory issues faced by various countries and has received wide attention from all sectors of society. The development of rapid and reliable detection methods for foodborne pathogens remains a hot research area for food safety and public health because of the limitations of complex steps, time-consuming, low sensitivity, or poor selectivity of commonly used methods. Surface-enhanced Raman spectroscopy (SERS), as a novel spectroscopic technique, has the advantages of high sensitivity, selectivity, rapid and nondestructive detection and has exhibited broad application prospects in the determination of pathogenic bacteria. In this study, the enhancement mechanisms of SERS are briefly introduced, then the characteristics and properties of liquid-phase, rigid solid-phase, and flexible solid-phase are categorized. Furthermore, a comprehensive review of the advances in label-free or label-based SERS strategies and SERS-compatible techniques for the detection of foodborne pathogens is provided, and the advantages and disadvantages of these methods are reviewed. Finally, the current challenges of SERS technology applied in practical applications are listed, and the possible development trends of SERS in the field of foodborne pathogens detection in the future are discussed.

Strategies and Challenges of Identifying Nanoplastics in Environment by Surface-Enhanced Raman Spectroscopy

Nanoplastics (<1000 nm) have been evidenced to be universal in a variety of environmental media. They pose a potential cytotoxicity and health risk due to their tiny size, which allows them to easily penetrate biological barriers and enter cells. Here, we briefly review the various prevalent analytical techniques or tools for identifying nanoplastics, and further move to focus on their advantages and disadvantages. Surface-enhanced Raman spectroscopy (SERS) has been implemented for the identification of individual nanoparticles because of its high sensitivity to molecules and ease of rapid characterization. Therefore, we introduce the SERS technique in the following aspects, (1) principles of SERS; (2) strategies and advances in SERS detection of nanoplastics; and (3) applying SERS to real environmental samples. We put our effort into the summarization of efficient SERS substrates that essentially enable the better detection of nanoplastics, and extend to discuss how the reported nanoplastics pretreatment methodologies can bring SERS analysis to practical applications. A further step moving forward is to investigate the problems and challenges of currently applied SERS detection methods and to look at future research needs in nanoplastics detection employing SERS analysis.

Spectro-Microscopic Techniques for Studying Nanoplastics in the Environment and in Organisms

Nanoplastics (NPs), small (<1 μm) polymer particles formed from bulk plastics, are a potential threat to human health and the environment. Orders of magnitude smaller than microplastics (MPs), they might behave differently due to their larger surface area and small size, which allows them to diffuse through organic barriers. However, detecting NPs in the environment and organic matrices has proven to be difficult, as their chemical nature is similar to these matrices. Furthermore, as their size is smaller than the (spatial) detection limit of common analytical tools, they are hard to find and quantify. We highlight different micro-spectroscopic techniques utilized for NP detection and argue that an analysis procedure should involve both particle imaging and correlative or direct chemical characterization of the same particles or samples. Finally, we highlight methods that can do both simultaneously, but with the downside that large particle numbers and statistics cannot be obtained.

Current Prospects for Plastic Waste Treatment

The excessive amount of global plastic produced over the past century, together with poor waste management, has raised concerns about environmental sustainability. Plastic recycling has become a practical approach for diminishing plastic waste and maintaining sustainability among plastic waste management methods. Chemical and mechanical recycling are the typical approaches to recycling plastic waste, with a simple process, low cost, environmentally friendly process, and potential profitability. Several plastic materials, such as polypropylene, polystyrene, polyvinyl chloride, high-density polyethylene, low-density polyethylene, and polyurethanes, can be recycled with chemical and mechanical recycling approaches. Nevertheless, due to plastic waste’s varying physical and chemical properties, plastic waste separation becomes a challenge. Hence, a reliable and effective plastic waste separation technology is critical for increasing plastic waste’s value and recycling rate. Integrating recycling and plastic waste separation technologies would be an efficient method for reducing the accumulation of environmental contaminants produced by plastic waste, especially in industrial uses. This review addresses recent advances in plastic waste recycling technology, mainly with chemical recycling. The article also discusses the current recycling technology for various plastic materials.

A Novel SERS Substrate Based on Discarded Oyster Shells for Rapid Detection of Organophosphorus Pesticide

Over the past few years, the concern for green chemistry and sustainable development has risen dramatically. Researchers make an effort to find solutions to difficult challenges using green chemical processes. In this study, we use oyster shells as a green chemical source to prepare calcium oxide nanoparticles (CaO-NPs). Transmission electron microscopy (TEM) results showed the CaO-NPs morphology, which was spherical in shape, 40 ± 5 nm in diameter, with uniform dispersion. We further prepared silver/polydopamine/calcium-oxide (Ag/PDA/CaO) nanocomposites as the surface-enhanced Raman scattering (SERS) substrates and evaluated their enhancement effect using the methyl parathion pesticide. The effective SERS detection limit of this method is 0.9 nM methyl parathion, which is much lower than the safety limits set by the Collaborative International Pesticides Analytical Council for insecticide in fruits. This novel green material is an excellent SERS substrate for future applications and meets the goal of green chemistry and sustainable development.