Although organic nanomaterials and inorganic nanoparticles possess inherent flexibility, facilitating functional modification, increased intracellular uptake and controllable drug release, their ...underlying cytotoxicity and lack of specificity still cause safety concerns. Owing to their merits, which include natural biocompatibility, structural stability, unsurpassed programmability, ease of internalization and editable functionality, tetrahedral DNA nanostructures show promising potential as an alternative vehicle for drug delivery and biomedical treatment. Here, we describe the design, fabrication, purification, characterization and potential biomedical applications of a self-assembling tetrahedral DNA nanostructure (TDN)-based multifunctional delivery system. First, relying on Watson-Crick base pairing, four single DNA strands form a simple and typical pyramid structure via one hybridization step. Then, the protocol details four different modification approaches, including replacing a short sequence of a single DNA strand by an antisense peptide nucleic acid, appending an aptamer to the vertex, direct incubation with small-molecular-weight drugs such as paclitaxel and wogonin and coating with protective agents such as cationic polymers. These modified TDN-based complexes promote the intracellular uptake and biostability of the delivered molecules, and show promise in the fields of targeted therapy, antibacterial and anticancer treatment and tissue regeneration. The entire duration of assembly and characterization depends on the cargo type and modification method, which takes from 2 h to 3 d.
Microplastics are emerging persistent contaminants of increasing concern. Although microplastics have been extensively detected in aquatic environments, their occurrence in soil ecosystems remains ...largely unexplored. This review focused on recent progress in analytical methods, pollution characteristics and ecological effects of microplastics in soils. In spite of the presence of microplastics in soils, no standardized methods are available for the quantification. Uniform protocols including microplastic extraction and identification are urgently needed to develop. In soil environments, main sources of microplastics include mulching film, sludge, wastewater irrigation and atmospheric deposition. The fate of microplastics is closely related to soil physio-chemistry and biota. Existing evidence shows that microplastics can influence soil biota at different trophic levels, and even threaten human health through food chains. Therefore, further research is needed to fully reveal the fate and ecological risks of microplastics in soils; and necessary action is required to control microplastic pollution in terrestrial ecosystems.
•Standardized methods need be developed for microplastic extraction/identification in soil.•Main sources of soil microplastics include mulching film, sludge and wastewater irrigation.•Microplastics can have ecological impacts on soil biota and even threaten human health.•Further research is needed to reveal the fate and ecological risks of soil microplastics.
Crowd evacuation of a building has been studied over the last decades. In this paper, seven methodological approaches for crowd evacuation have been identified. These approaches include cellular ...automata models, lattice gas models, social force models, fluid-dynamic models, agent-based models, game theoretic models, and approaches based on experiments with animals. According to available literatures, we discuss the advantages and disadvantages of these approaches, and conclude that a variety of different kinds of approaches should be combined to study crowd evacuation. Psychological and physiological elements affecting individual and collective behaviors should be also incorporated into the evacuation models.
Microplastics are emerging pollutants which have been extensively detected in water environments. However, little is known about microplastic pollution in soil environments. In this study, we ...investigated microplastics and mesoplastics in farmland soils from twenty vegetable fields around the suburbs of Shanghai. In each site, three duplicate soil samples were collected from shallow (0–3 cm) and deep soils (3–6 cm), respectively. Microplastics (sizes of 20 μm - 5 mm) and mesoplastics (5 mm - 2 cm) were detected using methods of density extraction, 30% H2O2 digestion and micro-fourier transform infrared spectroscopy. The abundance of microplastics was 78.00 ± 12.91 and 62.50 ± 12.97 items kg−1 in shallow and deep soils, respectively. While, mesoplastics were found with abundance of 6.75 ± 1.51 and 3.25 ± 1.04 items kg−1 in shallow and deep soils. Among these micro(meso)plastics, 48.79% and 59.81% were in size of <1 mm in shallow and deep soils. The main morphotypes of microplastics included fiber, fragment and film, mostly in color of black or transparent. Moreover, we found that topsoil contained higher concentrations and larger sizes of micro(meso)plastics than deep soil. In addition, the vast majority of micro(meso)plastics were polypropylene (50.51%) and polyethylene (43.43%). This study reveals occurrence and characteristics of microplastic pollution in typical farmland soils. It provides important data for subsequent research on microplatics in the terrestrial ecosystem.
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•Occurrence of micro(meso)plastics (M/MPs) was revealed in farmland soils in Shanghai.•Average abundance of microplastics was 78.00 and 62.50 items/kg in top and deep soils.•48.79–59.81% M/MPs were <1 mm, mostly with shapes of fiber, fragment and film.•Mean size of M/MPs was 1.91 and 1.48 mm in top (significantly larger) and deep soil.•Major of micro(meso)plastics were polypropylene (50.51%) and polyethylene (43.43%).
Microplastics have been frequently detected in aquatic environments, and there are increasing concerns about potential effects on biota. In this study, zebrafish Danio rerio and nematode ...Caenorhabditis elegans were used as model organisms for microplastic exposure in freshwater pelagic (i.e. water column) and benthic (i.e. sediment) environments. We investigated the toxic effects of five common types of microplastics: polyamides (PA), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and polystyrene (PS) particles. Results showed no or low lethality in D. rerio after exposure for 10d at 0.001–10.0mgL−1 microplastics. The PA, PE, PP and/or PVC microplastics with ~70μm size caused intestinal damage including cracking of villi and splitting of enterocytes. Exposure to 5.0mgm−2 microplastics for 2d significantly inhibited survival rates, body length and reproduction of C. elegans. Moreover, exposure to microplastics reduced calcium levels but increased expression of the glutathione S-transferase 4 enzyme in the intestine, which indicates intestinal damage and oxidative stress are major effects of microplastic exposure. Among 0.1, 1.0 and 5.0μm sizes of fluorescently labeled PS, 1.0μm particles caused the highest lethality, the maximum accumulation, the lowest Ca2+ level in the intestine and the highest expression of glutathione S-transferase 4 in nematodes. Taken together, these findings suggest that intestinal damage is a key effect of microplastics; and that the toxicity of microplastics is closely dependent on their size, rather than their composition.
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•Toxicity was comparatively studied on five common types of microplastics (MPs).•MPs with similar size induced intestine enterocyte damages in Danio rerio.•MPs reduced Ca2+ but increased gst-4 expression in intestine of Caenorhabditis elegans.•1.0μm MPs caused stronger toxicity than 0.1 or 5.0μm MPs in Caenorhabditis elegans.•Intestine damages are key effects of pristine MPs mostly dependent on their sizes.
Developing precise nanomedicines to improve the transport of anticancer drugs into tumor tissue and to the final action site remains a critical challenge. Here, we present a bioorthogonal in situ ...assembly strategy for prolonged retention of nanomedicines within tumor areas to act as drug depots. After extravasating into the tumor site, the slightly acidic microenvironment induces the exposure of cysteine on the nanoparticle surface, which subsequently undergoes a bioorthogonal reaction with the 2-cyanobenzothiazole group of another neighboring nanoparticle, enabling the formation of micro-sized drug depots to enhance drug retention and enrichment. This in situ nanoparticle assembly strategy remarkably improves the antimetastatic efficacy of extracellular-targeted drug batimastat, and also leads to the simultaneous enhanced retention and sustained release of multiple agents for combined cocktail chemoimmunotherapy to finally elicit a potent antitumor immune response. Such in situ assembly of nanomedicines represents a generalizable strategy towards extracellular drug delivery and cocktail chemoimmunotherapy.
Recent studies have demonstrated the occurrence of microplastic fibers (MFs) in soil environments. To determine whether MFs are harmful for soil biota, we evaluated toxic effects on terrestrial ...snails (Achatina fulica) after 28 d exposure to polyethylene terephthalate MFs at concentrations of 0.01–0.71 g kg−1 (dry soil weight). Digestion kinetics experiments on 24 snails showed that MFs can be ingested and excreted within 48 h. We found the appearance of cracks and deterioration on the surface of MFs after depuration by the digestive system. Prolonged exposure to 40 snails showed that 0.14–0.71 g kg−1 MFs caused an average reduction of 24.7–34.9% food intake and 46.6–69.7% excretion. 0.71 g kg−1 MFs induced significant villi damage in the gastrointestinal walls of 40% snails, but did not influence the histology of the liver and kidney. Moreover, 0.71 g kg−1 MFs exposure reduced glutathione peroxidase (59.3 ± 13.8%) and total antioxidant capacity (36.7 ± 8.5%), but elevated malondialdehyde level (58.0 ± 6.4%) in the liver, which indicates oxidative stress is involved in the toxic mechanism. Our results suggest that MFs have adverse impacts on the fitness of soil organisms, and highlight the ecological risks of microplastic pollution in terrestrial ecosystems.
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•0.01–0.71 g kg−1 PET fibers (ø76.3 μm) exposed to terrestrial snails in soil for 28 d.•Microplastic fibers (MFs) were uptake and depurated by the digestive tract in 48 h.•0.71 g kg−1 MFs caused a mean decrease of 34.9% food intake and 69.7% excretion.•0.71 g kg−1 MFs induced villi damages in walls of gastrointestinal tract of 40% snails.•0.71 g kg−1 MFs reduced GPx mean 59.3% and T-AOC 36.7%, elevated MDA 58.0%.
Capsule: Polyethylene terephthalate microfibers were ingested and caused gastrointestinal damage and oxidative stress in terrestrial snails.
•The ZnO@Ti3C2 MXene composite is obtained via a simple hydrothermal method for promoting the photocatalytic degradation.•The ZnO@Ti3C2 MXene composite presents the excellent photocatalytic ...degradation performance (94.84%).•The addition of Ti3C2 MXene forms a Schottky junction between ZnO and Ti3C2 MXene.•The Schottky junction prevents the photogenerated electrons returning to ZnO, and promotes the separation of carriers.
Herein, we report a ZnO@Ti3C2 MXene composite obtained using a simple hydrothermal method for increasing the photocatalytic degradation ability of methylene blue (MB). When the addition amount of Ti3C2 MXene is 50%, the ZnO@Ti3C2 MXene composite exhibited the best photocatalytic degradation performance (94.84%), and the reaction rate constant is 0.01223 min−1, which is 47 and 30 times of pure ZnO (5.59%, 0.026 ×10–2 min−1) and pure Ti3C2 MXene (7.56%, 0.04050 ×10–2 min−1), respectively. Moreover, the ZnO@Ti3C2 MXene composite exhibited good stability. The photocatalytic mechanism of ZnO@Ti3C2 MXene composite is proposed. The addition of Ti3C2 MXene forms a Schottky junction between ZnO and Ti3C2 MXene. The Schottky junction prevents the photogenerated electrons from returning to ZnO and promotes the separation of photogenerated electrons and holes, thus effectively improving the photocatalytic performance of ZnO@Ti3C2 MXene composite.
College life represents a key transitional period in the life of young adults that is marked by increased social engagement; living habits acquired during this period have implications on the future ...life of college students. Therefore, investigation of the determinants of health status of college students is a key imperative; however, there is limited evidence on the study of concomitant effects of physical activity (PA), sedentary time (ST), and sleep duration on the health-related quality of life (HRQOL) of college students.
This cross-sectional survey was conducted at a medical university in Shenyang in Northeast China in 2017. The study group comprised 926 undergraduate students. Data were collected by a self-administered questionnaire. PA, ST, sleep duration, and HRQOL were measured using the international physical activity questionnaire (IPAQ)-Long Form and the Chinese version of the 12-Item Short-Form Health Survey (SF-12). The association of PA, ST, and sleep duration with the HRQOL was examined using independent t-test, Pearson Chi-squared test, and multivariate linear regression analysis.
After adjusting for potential confounding factors, students who reported high PA had significantly higher physical component summary (PCS) score in the total study population and among female students than those who reported low PA, whereas students who reported moderate PA had significantly higher PCS score only among female students (P < 0.05). In the total study population and among male students, students who slept for ≥9 h/day had significantly higher mental component summary (MCS) score than those who slept for 7-< 8 h/day, whereas among only male students, those who slept for 8-< 9 h/day had significantly higher MCS score (P < 0.05). The interaction term between ST and PA was not statistically significant.
PA and sufficient sleep duration had a positive impact on the HRQOL of college students; however, ST was not associated with HRQOL and there was no interaction between the impact of ST and PA on the HRQOL of college students. Increasing PA and promoting adequate sleep duration are key health promotion strategies for college students.
This study examined the moderating effects of cultural orientations of peer groups on the relations between unsociability and psychological and school adjustment in Chinese children. Participants ...included 1,092 students (527 boys, M age = 12.21 years) in the sixth grade in elementary schools. Data on individualistic and collectivistic cultural orientations, unsociability, and adjustment were obtained from multiple sources including peer nominations, teacher ratings, self-reports, and school records. Using the Social Cognitive Map method, 193 peer groups were identified. Among the results, unsociability was negatively associated with peer preference and academic achievement in groups low on individualistic orientation but not in groups high on individualistic orientation. Unsociability was also negatively associated with peer preference more strongly in groups with higher scores of collectivistic orientation. The results suggested that, in general, unsociable children performed better in social and academical areas in more individualistically oriented groups and less collectivistically oriented groups. The cultural context of peer groups may play a significant role in shaping social and school adjustment of unsociable children.
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