Size-Dependent Uptake and Depuration of Nanoplastics in Tilapia (Oreochromis niloticus) and Distinct Intestinal Impacts.

Nanoplastics (NPs, <1 µm) are of great concern worldwide because of their high potential risk toward organisms in aquatic systems, while very little work has been focused on their tissue-specific toxicokinetics due to the limitations of NP quantification for such a purpose. In this study, NPs with two different sizes (86 and 185 nm) were doped with palladium (Pd) to accurately determine the uptake and depuration kinetics in various tissues (intestine, stomach, liver, gill, and muscle) of tilapia (Oreochromis niloticus) in water, and subsequently, the corresponding toxic effects in the intestine were explored. Our results revealed uptake and depuration constants of 2.70-378 L kg-1 day-1 and 0.138-0.407 day-1 for NPs in tilapia for the first time, and the NPs in tissues were found to be highly dependent on the particle size. The intestine exhibited the greatest relative accumulation of both sizes of NPs; the smaller NPs caused more severe damage than the larger NPs to the intestinal mucosal layer, while the larger NPs induced a greater impact on microbiota composition. The findings of this work explicitly indicate the size-dependent toxicokinetics and intestinal toxicity pathways of NPs, providing new insights into the ecological effects of NPs on aquatic organisms.

Protein Corona-Mediated Extraction for Quantitative Analysis of Nanoplastics in Environmental Waters by Pyrolysis Gas Chromatography/Mass Spectrometry.

There is a growing concern about the effects of nanoplastics on biological safety and human health because of their global ubiquity in the environment. Methodologies for quantitative analysis of nanoplastics are important for the critical evaluation of their possible risks. Herein, a sensitive yet simple and environmentally friendly extraction approach mediated by protein corona is developed and coupled to pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) for nanoplastic determination in environmental waters. The developed methodology involved the formation of protein corona by addition of bovine serum albumin (BSA) to samples and protein precipitation via salting out. Then, the resulting extract was directly introduced to Py-GC/MS for nanoplastic mass quantification. Taking 50 nm polystyrene (PS) particles as a model, the highest extraction efficiency for nanoplastics was achieved under the extraction conditions of BSA concentration of 20 mg/L, equilibration time of 5 min, pH 3.0, 10% (w/v) NaCl, incubation temperature of 80 °C, and incubation period of 15 min. The extraction was confirmed to be mediated by the protein corona by transmission electron microscopy (TEM) analysis of the extracted nanoplastics. In total, 1.92 and 2.82 µg/L PS nanoplastics were detected in river water and the influent of wastewater treatment plant (WWTP), respectively. Furthermore, the feasibility of the present methodology was demonstrated by applying to extract PS and poly(methyl methacrylate) (PMMA) nanoplastics from real waters with recoveries of 72.1-98.9% at 14.2-50.4 µg/L spiked levels. Consequently, our method has provided new insights and possibilities for the investigation of nanoplastic pollution and its risk assessment in the environment.

Quantitative Analysis of Polystyrene and Poly(methyl methacrylate) Nanoplastics in Tissues of Aquatic Animals.

Micro- and nanoplastics unavoidably enter into organisms and humans as a result of widespread exposures through drinking waters, foods, and even inhalation. However, owing to the limited availability of quantitative analytical methods, the effect of nanoplastics inside animal bodies is poorly understood. Herein, we report a sensitive and robust method to determine the chemical composition, mass concentration, and size distribution of nanoplastics in biological matrices. This breakthrough is based on a novel procedure including alkaline digestion and protein precipitation to extract nanoplastics from tissues of aquatic animals, followed by quantitative analysis with pyrolysis gas chromatography-mass spectrometry. The optimized procedure exhibited good reproducibility and high sensitivity with the respective detection limits of 0.03 µg/g for polystyrene (PS) nanoplastics and 0.09 µg/g poly(methyl methacrylate) (PMMA) nanoplastics. This method also preserved the original morphology and size of nanoplastics. Furthermore, to demonstrate the feasibility of the proposed method, 14 species of aquatic animals were collected, and PS nanoplastics in a concentration range of 0.093-0.785 µg/g were detected in three of these animals. Recovery rates of 73.0-89.1% were further obtained for PS and PMMA nanospheres when they were spiked into the tissues of Zebra snail and Corbicula fluminea at levels of 1.84-2.12 µg/g. Consequently, this method provides a powerful tool for tracking nanoplastics in animals.

Ultrastable radical-doped coordination compounds with antimicrobial activity against antibiotic-resistant bacteria.

In the present work, we have introduced a series of stable radical-doped coordination compounds composed of donor-acceptor structures and shown to produce organic radicals in situ as a result of unconventional lone pair-π interactions in ambient conditions. Inconspicuous lone pair-π and C-Hπ interactions were shown to play a key role in self-assembly as well as the charge transfer process, resulting in a long-lived charge-separated state able to generate organic radicals. The resultant species displayed broad-spectrum antimicrobial activity, including against multi-drug-resistant bacteria. This study unveiled the promise of reactive organic radical-doped materials as a new platform for developing antimicrobial agents that can overcome antibiotic resistance.