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

Convenient Size Analysis of Polystyrene Nanoplastics via Regulating the Radiative Transition Efficiency

Developing a convenient method to efficiently determine the size of nanoplastics in the environment is urgent in terms of ecological or human health protection. In this work, a novel strategy for discriminating the size of polystyrene (PS)-based nanoplastics was reported via regulating the radiative transition efficiency of NH2-UIO-66 (NU) with benzoic acid (BA) as the auxiliary ligand. The elaborately doped BA capped the defect sites and triggered nonradiative transition efficiency of NU. As a result, the formed composite (denoted as BA-NU) was more sensitive to interaction among neighboring NU and nanoplastics. The interaction between particles limited the rotation and vibration of the benzene ring within the BA-NU molecule, thus increasing the BA-NU fluorescence. The sensitivity of BA-NU on nanoplastics was well controlled by manipulating the doping contents of BA, leading to precisely tunable physicochemical properties for this structure. Deriving from the exquisitely designed nanostructures, the composite of BA-NU was successfully used to discriminate different size PS as an ultrasensitive turn-on probe. This work highlights the possibility of boosting the detection performance by regulating the main structure with guest molecules at the molecular level.

Rapid, sensitive, and non-destructive on-site quantitative detection of nanoplastics in aquatic environments using laser-backscattered fiber-embedded optofluidic chip

A definitive link between the micro- and nano-plastics (NPLs) and human health has been firmly established, emphasizing the higher risks posed by NPLs. The urgent need for a rapid, non-destructive, and reliable method to quantify NPLs remains unmet with current detection techniques. To address this gap, a novel laser-backscattered fiber-embedded optofluidic chip (LFOC) was constructed for the rapid, sensitive, and non-destructive on-site quantitation of NPLs based on 180º laser-backscattered mechanism. Our theoretical and experimental findings reveal that the 180º laser-backscattered intensities of NPLs were directly proportional to their mass and particle number concentration. Using the LFOC, we have successfully detected polystyrene (PS) NPLSs of varying sizes, with a minimum detection limit of 0.23 μg/mL (equivalent to 5.23 ×107 particles/mL). Moreover, PS NPLs of different sizes can be readily differentiated through a simple membrane-filtering method. The LFOC also demonstrates high sensitivity in detecting other NPLs, such as polyethylene, polyethylene terephthalate, polypropylene, and polymethylmethacrylate. To validate its practical application, the LFOC was used to detect PS NPLs in various aquatic environments, exhibiting excellent accuracy, reproducibility, and reliability. The LFOC provides a simple, versatile, and efficient tool for direct, on-site, quantitative detection of NPLs in aquatic environments.

Definition, detection, and tracking of nanowaste in foods: Challenges and perspectives

Commercial applications of nanotechnology in the food industry are rapidly increasing. Accordingly, there is a simultaneous increase in the amount and diversity of nanowaste, which arise as byproducts in the production, use, disposal, or recycling processes of nanomaterials utilized in the food industry. The potential risks of this nanowaste to human health and the environment are alarming. It is of crucial significance to establish analytical methods and monitoring systems for nanowaste to ensure food safety. This review provides comprehensive information on nanowaste in foods as well as comparative material on existing and new analytical methods for the detection of nanowaste. The article is specifically focused on nanowaste in food systems. Moreover, the current techniques, challenges as well as potential use of new and progressive methods are underlined, further highlighting advances in technology, collaborative efforts, as well as future perspectives for effective nanowaste detection and tracking. Such detection and tracking of nanowaste are required in order to effectively manage this type ofwasted in foods. Although there are devices that utilize spectroscopy, spectrometry, microscopy/imaging, chromatography, separation/fractionation, light scattering, diffraction, optical, adsorption, diffusion, and centrifugation methods for this purpose, there are challenges to be overcome in relation to nanowaste as well as food matrix and method characteristics. New technologies such as radio-frequency identification, Internet of things, blockchain, data analytics, and machine learning are promising. However, the cooperation of international organizations, food sector, research, and political organizations is needed for effectively managing nanowaste. Future research efforts should be focused on addressing knowledge gaps and potential strategies for optimizing nanowaste detection and tracking processes.

Nanoplastics in Water: Artificial Intelligence-Assisted 4D Physicochemical Characterization and Rapid In Situ Detection

For the first time, we present a much-needed technology for the in situ and real-time detection of nanoplastics in aquatic systems. We show an artificial intelligence-assisted nanodigital in-line holographic microscopy (AI-assisted nano-DIHM) that automatically classifies nano- and microplastics simultaneously from nonplastic particles within milliseconds in stationary and dynamic natural waters, without sample preparation. AI-assisted nano-DIHM identifies 2 and 1% of waterborne particles as nano/microplastics in Lake Ontario and the Saint Lawrence River, respectively. Nano-DIHM provides physicochemical properties of single particles or clusters of nano/microplastics, including size, shape, optical phase, perimeter, surface area, roughness, and edge gradient. It distinguishes nano/microplastics from mixtures of organics, inorganics, biological particles, and coated heterogeneous clusters. This technology allows 4D tracking and 3D structural and spatial study of waterborne nano/microplastics. Independent transmission electron microscopy, mass spectrometry, and nanoparticle tracking analysis validates nano-DIHM data. Complementary modeling demonstrates nano- and microplastics have significantly distinct distribution patterns in water, which affect their transport and fate, rendering nano-DIHM a powerful tool for accurate nano/microplastic life-cycle analysis and hotspot remediation.

A photoluminescence strategy for detection nanoplastics in water and biological imaging in cells and plants

Nanoplastics exposure poses a significant threat to the environment and human health, and accurate measurement of nanoparticles in aqueous solutions remains challenging. In this work, we synthesized the cationic fluorescent probe 4-[1-Cyano- 2-[4-(Diethylamino)-2-hydroxyphenyl]ethenyl]-1-ethylpyridinium (PCP) through a straightforward procedure for the rapid and accurate detection and labeling of nanoplastics in aqueous solutions. PCP binds to nanoplastics through electrostatic and hydrophobic interactions with restricted intramolecular rotation and exhibits enhanced fluorescence emission. Using carboxylation-modified polystyrene nanoplastics as a model, PCP could accurately detect concentrations as low as 0.525 mg∙L-1 in aqueous solution and perform wash-free semi-quantitative direct observation. The method demonstrated good reproducibility and recovery in actual sample spiking experiments. In addition, PCP-labeled nanoplastics were successfully used to visualize the uptake and distribution of cells and Arabidopsis thaliana when exposed to different concentrations of nanoplastics. This work provides a simple and sensitive method for efficiently identify, track, and quantify nanoplastics without requiring additional pretreatment and complex instrumentation, making it an ideal tool for accurately quantifying nanoplastics in aqueous solutions and studying the biological interactions of nanoplastics.

Nanoplastics increase the adverse impacts of lead on the growth, morphological structure and photosynthesis of marine microalga Platymonashelgolandica

Nanoplastics and heavy metals are common pollutants in coastal environments with high concerns, but their joint ecological risk to marine primary productivity remains unclear. In this study, the effects of 7, 70, 700 μg/L lead (Pb) single exposure and in combination with 200 μg/L polystyrene nanoplastics (NPs, 70 nm) on marine microalga Platymonas helgolandica were investigated. Pb single exposure induced a dose-dependent inhibition on the growth of P. helgolandica, which was associated with the reduced photosynthetic efficiency and nutrient accumulation. Compared to Pb single exposure, the addition of NPs significantly reduced the photosynthetic efficiency and aggravated the damage to cell structure. Reduced esterase activity and increased membrane permeability also indicated that NPs exacerbated the adverse effects of Pb on P. helgolandica. Thus, co-exposure to NPs and Pb induced more severe impacts on marine microalgae, suggesting that the joint ecological risk of NPs and heavy metals to marine primary productivity merits more attention.

Sub-10 nm Nanoparticle Detection Using Multi-Technique-Based Micro-Raman Spectroscopy

Microplastic pollution is a growing public concern as these particles are ubiquitous in various environments and can fragment into smaller nanoplastics. Another environmental concern arises from widely used engineered nanoparticles. Despite the increasing abundance of these nano-sized pollutants and the possibility of interactions with organisms at the sub cellular level, with many risks still being unknown, there are only a few publications on this topic due to the lack of reliable techniques for nanoparticle characterization. We propose a multi-technique approach for the characterization of nanoparticles down to the 10 nm level using standard micro-Raman spectroscopy combined with standard atomic force microscopy. We successfully obtained single-particle spectra from 25 nm sized polystyrene and 9 nm sized TiO2 nanoparticles with corresponding mass limits of detection of 8.6 ag (attogram) and 1.6 ag, respectively, thus demonstrating the possibility of achieving an unambiguous Raman signal from a single, small nanoparticle with a resolution comparable to more complex and time-consuming technologies such as Tip-Enhanced Raman Spectroscopy and Photo-Induced Force Microscopy.

Recent Study of Separation and Identification of Micro- and Nanoplastics for Aquatic Products

Micro- and nanoplastics (MNPs) are polymeric compounds widely used in industry and daily life. Although contamination of aquatic products with MNPs exists, most current research on MNPs focuses on environmental, ecological, and toxicological studies, with less on food safety. Currently, the extent to which aquatic products are affected depends primarily on the physical and chemical properties of the consumed MNPs and the content of MNPs. This review presents new findings on the occurrence of MNPs in aquatic products in light of their properties, carrier effects, chemical effects, seasonality, spatiality, and differences in their location within organisms. The latest studies have been summarized for separation and identification of MNPs for aquatic products as well as their physical and chemical properties in aquatic products using fish, bivalves, and crustaceans as models from a food safety perspective. Also, the shortcomings of safety studies are reviewed, and guidance is provided for future research directions. Finally, gaps in current knowledge on MNPs are also emphasized.