What to Do about Plastics? Lessons from a Study of United Kingdom Plastics Flows

Isolation of marine polyethylene (PE)-degrading bacteria and its potential degradation mechanisms

Microbial degradation of polyethylene (PE) offers a promising solution to plastic pollution in the marine environment, but research in this field is limited. In this study, we isolated a novel marine strain of Pseudalkalibacillus sp. MQ-1 that can degrade PE. Scanning electron microscopy and water contact angle results showed that MQ-1 could adhere to PE films and render them hydrophilic. Analyses using X-ray diffraction, fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy showed a decrease in relative crystallinity, the appearance of new functional groups and an increase in the oxygen-to‑carbon ratio of the PE films, making them more susceptible to degradation. The results of gel permeation chromatography and liquid chromatography-mass spectrometry indicated the depolymerization of the long PE chains, with the detection of an intermediate, decanediol. Furthermore, genome sequencing was employed to investigate the underlying mechanisms of PE degradation. The results of genome sequencing analysis identified the genes associated with PE degradation, including cytochrome P450, alcohol dehydrogenase, and aldehyde dehydrogenase involved in the oxidative reaction, monooxygenase related to ester bond formation, and esterase associated with ester bond cleavage. In addition, enzymes involved in fatty acid metabolism and intracellular transport have been identified, collectively providing insights into the metabolic pathway of PE degradation.

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.

Degradation of microplastic in water by advanced oxidation processes

Plastic products have gained global popularity due to their lightweight, excellent ductility, high durability, and portability. However, out of the 8.3 billion tons of plastic waste generated by human activities, 80% of plastic waste is discarded due to improper disposal, and then transformed into microplastic pollution under the combined influence of environmental factors and microorganisms. In this comprehensive study, we present a thorough review of recent advancements in research on the source, distribution, and effect of microplastics. More importantly, we conducted deep research on the catalytic degradation technologies of microplastics in water, including advanced oxidation and photocatalytic technologies, and elaborated on the mechanisms of microplastics degradation in water. Besides, various strategies for mitigating microplastic pollution in aquatic ecosystems are discussed, ranging from policy interventions, the initiative for plastic recycling, the development of efficient catalytic materials, and the integration of multiple technological approaches. This review serves as a valuable resource for addressing the challenge of removing microplastic contaminants from water bodies, offering insights into effective and sustainable solutions.

Transcriptomic and metabolomic analysis unveils nanoplastic-induced gut barrier dysfunction via STAT1/6 and ERK pathways

The widespread prevalence of micro and nanoplastics in the environment raises concerns about their potential impact on human health. Recent evidence demonstrates the presence of nanoplastics in human blood and tissues following ingestion and inhalation, yet the specific risks and mechanisms of nanoplastic toxicity remain inadequately understood. In this study, we aimed to explore the molecular mechanisms underlying the toxicity of nanoplastics at both systemic and molecular levels by analyzing the transcriptomic/metabolomic responses and signaling pathways in the intestines of mice after oral administration of nanoplastics. Transcriptome analysis in nanoplastic-administered mice revealed a notable upregulation of genes involved in pro-inflammatory immune responses. In addition, nanoplastics substantially reduced the expression of tight junction proteins, including occludin, zonula occluden-1, and tricellulin, which are crucial for maintaining gut barrier integrity and function. Importantly, nanoplastic administration increased gut permeability and exacerbated dextran sulfate sodium-induced colitis. Further investigation into the underlying molecular mechanisms highlighted significant activation of signaling transsducer and activator of transcription (STAT)1 and STAT6 by nanoplastic administration, which was in line with the elevation of interferon and JAK-STAT pathway signatures identified through transcriptome enrichment analysis. Additionally, the consumption of nanoplastics specifically induced nuclear factor kappa-B (NF-κB) and extracellular signal-regulated kinase (ERK)1/2 signaling pathways in the intestines. Collectively, this study identifies molecular mechanisms contributing to adverse effects mediated by nanoplastics in the intestine, providing novel insights into the pathophysiological consequences of nanoplastic exposure.

CO2-facilitated upcycling of polyolefin plastics to aromatics at low temperature

Plastics are one of the most produced synthetic materials and largest commodities, used in numerous sectors of human life. To upcycle waste plastics into value-added chemicals is a global challenge. Despite significant progress in pyrolysis and hydrocracking, which mainly leads to the formation of pyrolysis oil, catalytic upcycling to value-added aromatics, including benzene, toluene and xylene (BTX), in one step, is still limited by high reaction temperatures (>500°C) and a low yield. We report herein CO2-facilitated upcycling of polyolefins and their plastic products to aromatics below 300°C, enabled by a bifunctional Pt/MnOx-ZSM-5 catalyst. ZSM-5 catalyzes cracking of polyolefins and aromatization, generating hydrogen at the same time, while Pt/MnOx catalyzes the reaction of hydrogen with CO2, consequently driving the reaction towards aromatization. Isotope experiments reveal that 0.2 kg CO2 is consumed per 1.0 kg polyethylene and 90% of the consumed CO2 is incorporated into the aromatic products. Furthermore, this new process yields 0.63 kg aromatics (BTX accounting for 60%), comparing favorably with the conventional pyrolysis or hydrocracking processes, which produce only 0.33 kg aromatics. In this way, both plastic waste and the greenhouse gas CO2 are turned into carbon resources, providing a new strategy for combined waste plastics upcycling and carbon dioxide utilization.