Effects of microplastics on typical macrobenthos in sargassum ecosystems.

Recently, microplastics (MPs) have attracted extensive attention to their wide distribution and potential toxicity in ecosystems. However, there was a lack of research focused on MPs in seaweed bed ecosystems. This study investigated the distribution and toxicity of MPs in macrobenthos in Sargassum ecosystem. According to the in-situ investigation results, the abundance of MPs in the sediment was 0.9-2.3 items/g, the indoor microcosmic experiment was constructed. After exposure to MPs (0, 2, and 20 items/g) for 30 days, the abundance of MPs in macrobenthos exhibits a concentration-dependent increase. However, there was no significant bioaccumulation of MPs at the trophic level. The indoor toxicity test revealed that MPs induced oxidative stress and altered intestinal microflora composition in macrobenthos, even at actual environmental concentrations (2 items/g). It may result in a perturbation of the organism's homeostatic equilibrium. High-concentration (20 items/g) MPs had a greater impact on alkaline phosphatase (AKP) in Mollusks. The increase in AKP activity could be indicative of an adaptive mechanism in some macrobenthos while the decline in AKP activity might signal a decrease in their survival. These results elucidated the fate of MPs in ecosystem and the ecological risks of MPs to large benthic animals on model environmental conditions.

Effects of emulsifiers on lipid metabolism and performance of yellow-feathered broilers.

BACKGROUND: Reducing production costs while producing high-quality livestock and poultry products is an ongoing concern in the livestock industry. The addition of oil to livestock and poultry diets can enhance feed palatability and improve growth performance. Emulsifiers can be used as potential feed supplements to improve dietary energy utilization and maintain the efficient productivity of broilers. Therefore, further investigation is warranted to evaluate whether dietary emulsifier supplementation can improve the efficiency of fat utilization in the diet of yellow-feathered broilers. In the present study, the effects of adding emulsifier to the diet on lipid metabolism and the performance of yellow-feathered broilers were tested. A total of 240 yellow-feasted broilers (21-day-old) were randomly divided into 4 groups (6 replicates per group, 10 broilers per replicate, half male and half female within each replicate). The groups were as follows: the control group (fed with basal diet), the group fed with basal diet supplemented with 500 mg/kg emulsifier, the group fed with a reduced oil diet (reduced by 1%) supplemented with 500 mg/kg emulsifier, and the group fed with a reduced oil diet supplemented with 500 mg/kg emulsifier. The trial lasted for 42 days, during which the average daily feed intake, average daily gain, and feed-to-gain ratio were measured. Additionally, the expression levels of lipid metabolism-related genes in the liver, abdominal fat and each intestinal segment were assessed. RESULTS: The results showed that compared with the basal diet group, (1) The average daily gain of the basal diet + 500 mg/kg emulsifier group significantly increased (P < 0.05), and the half-even-chamber rate was significantly increased (P < 0.05); (2) The mRNA expression levels of Cd36, Dgat2, Apob, Fatp4, Fabp2, and Mttp in the small intestine were significantly increased (P < 0.05). (3) Furthermore, liver TG content significantly decreased (P < 0.05), and the mRNA expression level of Fasn in liver was significantly decreased (P < 0.05), while the expression of Apob, Lpl, Cpt-1, and Pparα significantly increased (P < 0.05). (4) The mRNA expression levels of Lpl and Fatp4 in adipose tissue were significantly increased (P < 0.05), while the expression of Atgl was significantly decreased (P < 0.05). (5) Compared with the reduced oil diet group, the half-evading rate and abdominal fat rate of broilers in the reduced oil diet + 500 mg/kg emulsifier group were significantly increased (P < 0.05), and the serum level of LDL-C increased significantly (P < 0.05)0.6) The mRNA expression levels of Cd36, Fatp4, Dgat2, Apob, and Mttp in the small intestine were significantly increased (P < 0.05). 7) The mRNA expression levels of Fasn and Acc were significantly decreased in the liver (P < 0.05), while the mRNA expression levels of Lpin1, Dgat2, Apob, Lpl, Cpt-1, and Pparα were significantly increased (P < 0.05). CONCLUSIONS: These results suggest that dietary emulsifier can enhance the fat utilization efficiency of broilers by increasing the small intestinal fatty acid uptake capacity, inhibiting hepatic fatty acid synthesis and promoting hepatic TG synthesis and transport capacity. This study provides valuable insights for the potential use of emulsifier supplementation to improve the performance of broiler chickens.

In situ surface-enhanced Raman spectroscopy for the detection of nanoplastics: A novel approach inspired by the aging of nanoplastics.

Nanoplastics (NPs) present a hidden risk to organisms and the environment via migration and enrichment. Detecting NPs remains challenging because of their small size, low ambient concentrations, and environmental variability. There is an urgency to exploit detection approaches that are more compatible with real-world environments. Herein, this study provides a surface-enhanced Raman spectroscopy (SERS) technique for the in situ reductive generation of silver nanoparticles (Ag NPs), which is based on photoaging-induced modifications in NPs. The feasibility of generating Ag NPs on the surface of NPs was derived by exploring the photoaging mechanism, which was then utilized to SERS detection. The approach was applied successfully for the detection of polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET) NPs with excellent sensitivity (e.g., as low as 1 × 10-6 mg/mL for PVC NPs, and an enhancement factor (EF) of up to 2.42 × 105 for small size PS NPs) and quantitative analytical capability (R2 > 0.95579). The method was successful in detecting NPs (PS NPs) in lake water. In addition, satisfactory recoveries (93.54-105.70 %, RSD < 12.5 %) were obtained by spiking tap water as well as lake water, indicating the applicability of the method to the actual environment. Therefore, the proposed approach offers more perspectives for testing real environmental NPs.

High sensitivity in quantitative analysis of mixed-size polystyrene micro/nanoplastics in one step.

As emerging environmental pollutants, microplastics (MPs) and nanoplastics (NPs) pose a serious threat to human health. Owing to the lack of feasible and reliable analytical methods, the separation and identification of MPs and NPs of different sizes remains a challenge. In this study, a hyphenated method involving filtration and surface-enhanced Raman spectroscopy (SERS) for the separation and identification of MPs and NPs is reported. This method not only avoids the loss of MPs and NPs during the transfer process but also provides an excellent SERS substrate. The SERS substrate was fabricated by electrochemically depositing silver particles onto the reduced graphene oxide layer coated on stainless steel mesh. Results show that polystyrene (PS) MPs and NPs are efficiently separated on the SERS substrate via vacuum filtration, resulting in high retention rates (74.26 % ± 1.58 % for 100 nm, 81.06 % ± 1.49 % for 500 nm, and 97.73 % ±0.11 % for 5 µm) and low limit of detection (LOD). The LOD values of 100 nm, 500 nm, and 5 µm PS are 8.89 × 10-5, 3.39 × 10-5, and 1.57 × 10-4 µg/mL, respectively. More importantly, a linear relationship for uniform quantification of 100 nm, 500 nm, 3 µm and 5 µm PS was established, and the relationship is Y = 225.61 lgX + 1076.36 with R2 = 0.980. The method was validated for the quantitative analysis of a mixture of 100 nm, 500 nm PS NPs, 3 µm and 5 µm PS MPs in a ratio of 1:1:1:1, which successfully approaches the evaluation of evaluated PS NPs in the range of 10-4-10 µg/mL with an LOD value of approximately 7.82 × 10-5 µg/mL. Moreover, this method successfully detected (3.87 ± 0.06) × 10-5 µg MPs and NPs per gram of oyster tissue.

Differences in toxicity induced by the various polymer types of nanoplastics on HepG2 cells.

The problem of microplastics (MPs) contamination in food has gradually come to the fore. MPs can be transmitted through the food chain and accumulate within various organisms, ultimately posing a threat to human health. The concentration of nanoplastics (NPs) exposed to humans may be higher than that of MPs. For the first time, we studied the differences in toxicity, and potential toxic effects of different polymer types of NPs, namely, polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polystyrene (PS) on HepG2 cells. In this study, PET-NPs, PVC-NPs, and PS-NPs, which had similar particle size, surface charge, and shape, were prepared using nanoprecipitation and emulsion polymerization. The results of the CCK-8 assay showed that the PET-NPs and PVC-NPs induced a decrease in cell viability in a concentration-dependent manner, and their lowest concentrations causing significant cytotoxicity were 100 and 150 µg/mL, respectively. Moreover, the major cytotoxic effects of PET-NPs and PVC-NPs at high concentrations may be to induce an increase in intracellular ROS, which in turn induces cellular damage and other toxic effects. Notably, our study suggested that PET-NPs and PVC-NPs may induce apoptosis in HepG2 cells through the mitochondrial apoptotic pathway. However, no relevant cytotoxicity, oxidative damage, and apoptotic toxic effects were detected in HepG2 cells with exposure to PS-NPs. Furthermore, the analysis of transcriptomics data suggested that PET-NPs and PVC-NPs could significantly inhibit the expression of DNA repair-related genes in the p53 signaling pathway. Compared to PS-NPs, the expression levels of lipid metabolism-related genes were down-regulated to a greater extent by PET-NPs and PVC-NPs. In conclusion, PET-NPs and PVC-NPs were able to induce higher cytotoxic effects than PS-NPs, in which the density and chemical structure of NPs of different polymer types may be the key factors causing the differences in toxicity.

The effect of polystyrene nanoplastics on arsenic-induced apoptosis in HepG2 cells.

Microplastics are detrimental to the environment. However, the combined effects of microplastics and arsenic (As) remain unclear. In this study, we investigated the combined effects of polystyrene (PS) microplastics and As on HepG2 cells. The results showed that PS microplastics 20, 50, 200, and 500 nm in size were taken up by HepG2 cells, causing a decrease in cellular mitochondrial membrane potential. The results of lactate dehydrogenase release and flow cytometry showed that PS microplastics, especially those of 50 nm, enhanced As-induced apoptosis. In addition, transcriptome analysis revealed that TP53, AKT1, CASP3, ACTB, BCL2L1, CASP8, XIAP, MCL1, NFKBIA, and CASP7 were the top 10 hub genes for PS that enhanced the role of As in HepG2 cell apoptosis. Our results suggest that nano-PS enhances As-induced apoptosis. Furthermore, this study is important for a better understanding of the role of microplastics in As-induced hepatotoxicity.

Exosomal miRNA analysis provides new insights into exposure to nanoplastics and okadaic acid.

As an emerging environmental pollutant, nanoplastics (NPs) have attracted wide attention in terms of their impact on the ecological environment and human health. Currently, researches on the cytotoxicity of NPs mainly focus on oxidative stress, damage to the cell membrane and organelles, induction of immune response and genotoxicity. Okadaic acid (OA) is the main component of diarrheal shellfish toxin. Based on the previous combined toxicity exploration of polystyrene (PS) NPs and (OA) to human gastric adenocarcinoma (AGS) cells, cell-derived exosomes were extracted and exosomal miRNA profiles were analyzed for the first time in this study. The results showed that the composition of miRNAs varied after the exposure of NPs and OA. Specifically, the expression of miR-1-3p in both PS-Exo and PS-OA-Exo was significantly reduced. And the expression of miR-1248 was upregulated most significantly by comparing the DE miRNAs between PS-Exo and PS-OA-Exo. MiR-1-3p and miR-1248 may be the key genes for the combined toxicity of NPs and OA. After analysis, we found that both the decreased expression of miR-1-3p and the increased expression of miR-1248 can increase the expression of FN1 and affect DNA replication, which was surprisingly consistent with the results of our previous cytotoxicity studies. Since exosomal miRNAs are selectively encapsulated by donor cell, we speculate that the changes of exosomal miRNAs may due to the synchronous changes of intracellular environment and the downregulation of intracellular FN1 may be attributed to decreased expression of miR-1-3p and increased expression of miR-1248 in donor cells. Accordingly, we come to the conclusion that the changes of miRNAs in the exosomes derived from AGS cells after environmental stimulation could reflect the biological effects of donor cells.

Overcoming the fluorescent interference during Raman spectroscopy detection of microplastics.

Owing to environmental concerns, microplastics pollution has been the object of increasing attention. Currently, the chemical composition of microplastics is commonly detected using Raman spectroscopy. Nevertheless, the Raman spectra of microplastics may be overlaid by signals derived from additives (e.g., pigment), resulting in serious interference. In this study, an efficient method is proposed to overcome the interference of fluorescence during Raman spectroscopic detection of microplastics. Four catalysts of Fenton's reagent (Fe2+, Fe3+, Fe3O4, and K2Fe4O7) have been investigated for their capacity to generate hydroxyl radical (•OH), thus potentially eliminating the fluorescent signals in microplastics. The results indicate that the Raman spectrum of microplastics treated with Fenton's reagent can be efficiently optimized in the absence of spectral processing. This method has been successfully applied to the detection of microplastics collected from mangroves, featuring a range of colours and shapes. Consequentially, after 14 h of treatment with sunlight-Fenton (Fe2+: 1 × 10-|6 M, H2O2: 4 M), the Raman spectra matching-degree (RSMD) of all microplastics were >70.00 %. The innovative strategy discussed in this manuscript can greatly promote the application of Raman spectroscopy in the detection of real environmental microplastics, overcoming interfering signals derived from additives.

Distribution and risk assessment of microplastics in typical ecosystems in the South China Sea.

Microplastic pollution in the marine environment has attracted worldwide attention. The South China Sea is considered a hotspot for microplastic pollution due to the developed industries and high population density around the South China Sea. The accumulation of microplastics in ecosystems can adversely affect the health of the environment and organisms. This paper reviews the recent microplastic studies conducted in the South China Sea, which novelty summarizes the abundance, types, and potential hazards of microplastics in coral reef ecosystems, mangrove ecosystems, seagrass bed ecosystems, and macroalgal ecosystems. A summary of the microplastic pollution status of four ecosystems and a risk assessment provides a more comprehensive understanding of the impact of microplastic pollution on marine ecosystems in the South China Sea. Microplastic abundances of up to 45,200 items/m3 were reported in coral reef surface waters, 5738.3 items/kg in mangrove sediments, and 927.3 items/kg in seagrass bed sediments. There are few studies of microplastics in the South China Sea macroalgae ecosystems. However, studies from other areas indicate that macroalgae can accumulate microplastics and are more likely to enter the food chain or be consumed by humans. Finally, this paper compared the current risk levels of microplastics in the coral reef, mangrove, and seagrass bed ecosystems based on available studies. Pollution load index (PLI) ranges from 3 to 31 in mangrove ecosystems, 5.7 to 11.9 in seagrass bed ecosystems, and 6.1 to 10.2 in coral reef ecosystems, respectively. The PLI index varies considerably between mangroves depending on the intensity of anthropogenic activity around the mangrove. Further studies on seagrass beds and macroalgal ecosystems are required to extend our understanding of microplastic pollution in marine environments. Recent microplastic detection in fish muscle tissue in mangroves requires more research to further the biological impact of microplastic ingestion and the potential food safety risks.

Polystyrene nanoplastics promote the apoptosis in Caco-2 cells induced by okadaic acid more than microplastics.

Microplastics (MPs) are widespread in the environment and can be ingested through food, water, and air, posing a threat to human health. In addition, MPs can have a potential combined effect with other toxic compounds. Polystyrene (PS) has been shown to enhance the cytotoxicity of okadaic acid (OA). However, it remains unclear whether this enhancement effect is related to the size of PS particles. In this study, we investigated the mechanism of the combined effect of PS microplastics (PS-MPs) or PS nanoplastics (PS-NPs) and OA on Caco-2 cells. The results indicated that PS-NPs enhanced the cytotoxicity of OA and induced endoplasmic reticulum (ER) stress-mediated apoptosis in Caco-2 cells, compared to PS-MPs. Specifically, PS-NPs and OA cause more severe oxidative stress, lactate dehydrogenase (LDH) release, and mitochondrial membrane depolarization. Furthermore, it induced intracellular calcium overload through store-operated channels (SOCs) and activated the PERK/ATF-4/CHOP pathway to cause ER stress. ER stress promoted mitochondrial damage and finally activated the caspase family to induce apoptosis. This study provided an indirect basis for the assessment of the combined toxicity of MPs or NPs with OA.

Occurrence of antibiotic resistance genes carried by plastic waste from mangrove wetlands of the South China Sea.

Plastic waste can carry organisms such as bacterial pathogens and antibiotic resistance genes (ARGs) over long distances. However, only few studies have been conducted on the occurrence of ARGs in plastic waste from mangrove wetlands. This study evaluated the distribution characteristics and ecological risks of plastic waste from mangroves in the coastal areas of the South China Sea. The correlation between anthropogenic activity levels and abundance of ARGs in mangroves was evaluated. Transparent and white were the common colors of plastic waste in mangroves. The main shapes of plastic waste were foam and film. The predominant types of plastic waste order were as follows: polyethylene (30.18 %) > polypropylene (27.51 %) > polystyrene (23.59 %). The living area (LA) mangroves had the highest polymer hazard and pollution load indices of 329.09 and 10.03, respectively. The abundance of ARGs (5.08 × 108 copies/g) on the plastic surface in LA mangroves was significantly higher than that of the other mangrove areas. Furthermore, there was a significant correlation between ARGs and intI1 on the plastic surface in mangroves. Correlation analysis between the ARGs and intI1 showed that most of the ARGs were correlated with intI1 except for msbA. In LA mangroves, sociometric and environmental factors showed significant correlations with the absolute abundances of the four ARGs and intI1, indicating that anthropogenic activities may lead to changes in the amount of ARGs on plastic surfaces. Furthermore, the ARG storage of plastic waste from different mangroves was as follows: protected areas (3.12 × 1017 copies) > living areas (2.99 × 1017 copies) > aquaculture pond areas (2.88 × 1017 copies). The higher ARG storage of LA mangroves, with the smallest area, greatly increased its ecological risk. The results of this study can provide basic data for processes that influence the distribution of plastic waste and ARGs in mangroves.

Extracellular vesicles derived from Pinctada martensii mucus regulate skin inflammation via the NF-κB/NLRP3/MAPK pathway.

Extracellular vesicles (EVs) and their exosome subsets are vesicle-like nanoparticles (EVs) that are secreted by cells and contain various factors that treat various diseases. However, studies on extracting EVs from marine shellfish are still relatively lacking. In this study, EVs were isolated from Pinctada martensii mucus and the efficacy of EVs in modulating the inflammatory environment was demonstrated. A human skin inflammatory cell model was established to investigate the effect of Pinctada martensii mucus-derived EVs on inflammation. The results showed that EVs could restore the viability of inflammatory HaCaT cells and decrease the level of reactive oxygen species (ROS), as well as the mRNA expression of IL-6, IL-8 and TNF-α. The inflammation of HaCaT cells was treated by inhibiting the activation of the MAPK, NF-κB and NLRP3 inflammasome signaling pathways, which prevented the phosphorylation of related inflammatory proteins and the entry of P65 protein into the nucleus. This study provides novel EVs from marine shellfish-derived bioactive materials.

Separation of false-positive microplastics and analysis of microplastics via a two-phase system combined with confocal Raman spectroscopy.

In the field of microplastics research, more accurate standardised methods and analytical techniques still need to be explored. In this study, a new method for the microplastics quantitatively and qualitatively analysis by two-phase (ethyl acetate-water) system combined with confocal Raman spectroscopy was developed. Microplastics can be separated from false-positive microplastics in beach sand and marine sediment, attributing to the hydrophobic-lipophilic interaction (HLI) of the two-phase system. Results show that the recovery rates of complex environment microplastics (polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyamide 66 (PA 66), polycarbonate (PC) and polyethylene (PE)) are higher than 92.98%. Moreover, the new technique can also be used to detect hydrophobic and lipophilic antibiotics, such as sulfamethoxazole (SMX), erythromycin (EM), madimycin (MD), and josamycin (JOS), which adsorbed on microplastics and are extracted based on the dissolving-precipitating mechanism. This innovative research strategy provides a new scope for further detection of marine environment microplastics and toxic compounds adsorbed on its surface.

Target-Modulated Hydrophobic Precipitation in Photocatalytic Nanochannels for Sensitive Detection of Alpha Fetoprotein.

It is important to detect cancer biomarkers at an early stage of tumor development for the effective diagnosis and treatment of cancer. As a well-known probe for detecting superoxide (·O2-) radicals, nitro blue tetrazolium (NBT) can rapidly react with ·O2- to form a hydrophobic formazan precipitate. In this study, by deliberately utilizing this reaction, Pt asymmetrically decorated on a TiO2 nanochannel membrane (Pt/TiNM) is explored to fabricate an electrochemical immunosensing platform with outstanding selectivity and ultrahigh sensitivity. Using NBT as the substrate, hydrophobic formazan precipitation induces a substantial block of ionic diffusion flux in nanochannels. Using alpha fetoprotein (AFP) as the target analyte, the established immunorecognition event was used to induce MoS2-Ab2 conjugates. Thanks to the excellent light-shielding ability of MoS2 nanosheets, the production of ·O2- radicals from the photocatalysis of Pt/TiNM is effectively depressed because of the attenuated arrival of light. The reduced formazan precipitation results in ionic transport changes in nanochannels, which in turn enables the selective recognition of AFP down to 2 ng mL-1. This target-modulated sensing strategy is also capable of sensing other immune targets, thus paving a new way for designing nanochannel-based sensing platforms.

Understanding of chiral site-dependent enantioselective identification on a plasmon-free semiconductor based SERS substrate.

Chiral differentiation is an important topic in diverse fields ranging from pharmaceutics to chiral synthesis. The improvement of sensitivity and the elucidation of the mechanism of chiral recognition are still the two main challenges. Herein, a plasmon-free semiconductive surface-enhanced Raman spectroscopy (SERS) substrate with sensitive chiral recognition ability is proposed for the discrimination of enantiomers. A homochiral environment is constructed by typical π-π stacking between l-tryptophan (l-Trp) and phenyl rings on well-aligned TiO2 nanotubes (TiO2 NTs). Using 3,4-dihydroxyphenylalanine (DOPA) enantiomers as the targets and the chelating interaction of Fe3+-DOPA for the onsite growth of Prussian blue (PB), the enantioselectivity difference between l-DOPA and d-DOPA on the homochiral substrate can be directly monitored from PB signals in the Raman-silent region. By combining the experimental results with molecular dynamic (MD) simulations, it is found that satisfactory enantioselective identification not only requires a homochiral surface but also largely depends on the chiral center environment-differentiated hydrogen-bond formation availability.

Impact of the surrounding environment on antibiotic resistance genes carried by microplastics in mangroves.

The pollution of antibiotic resistance genes (ARGs) carried by microplastics (MPs) is a growing concern. Mangroves are located at the intersection of land and sea and are seriously affected by MP pollution. However, few studies have systematic research evaluating the transmission risk of ARGs carried by MPs in mangroves. We conducted in situ experiments by burying five different MPs (polypropylene, high-density polyethylene, polystyrene, polyethylene glycol terephthalate, and polycaprolactone particles) in mangroves with different surrounding environments. A total of 10 genes in the MPs of mangroves were detected using quantitative real-time polymerase chain reactions, including eight ARGs and two mobile genetic elements (MGEs). The abundance of ARGs in Guanhai park mangroves in living areas (GH) was higher than that of Gaoqiao mangroves in protected areas (GQ) and Beiyue dike mangroves in aquaculture pond areas (BY). Pathogenic bacteria, such as Acinetobacter, Bacillus, and Vibrio were found on the MP surfaces of the mangroves. The number of ARGs carried by multiple drug-resistant bacteria in the GH mangroves was greater than that in the GQ and BY mangroves. Moreover, the ARGs carried by MPs in GH mangroves had the highest potential transmission risk by horizontal gene transfer. Sociometric and environmental factors were the main drivers shaping the distribution characteristics of ARGs and MGEs. Polypropylene and high-density polyethylene particles are preferred substrates for obtaining diffuse ARGs. This study investigated the drivers of ARGs in the MPs of mangroves and provided essential guidance on the use and handling of plastics.

Microplastics accumulation in mangroves increasing the resistance of its colonization Vibrio and Shewanella.

The enrichment of various pollutants in mangrove has attracted widespread attention. Especially, microplastics accumulation in mangrove may provide a more challenging ecological colonization site by enriching pollutants, thus affecting the change of microplastics antibiotic resistance and increasing the risk of antibiotic failure. Herein, the antibiotic-resistant of microplastics and sediment from mangrove were investigated. The results show that isolates are mainly colonized by Vibrio parahemolyticus (V. parahemolyticus), Vibrio alginolyticus (V. alginolyticus), and Shewanella. 100% mangrove microplastics isolates are resistant to chloramphenicol, cefazolin, and tetracycline, especially amoxicillin clavulanate and ampicillin. Meanwhile, the multiple antibiotics resistance (MAR) indexes of V. parahaemolyticus, Shewanella, and V. alginolyticus in mangrove microplastics are 0.72, 0.77, and 0.77, respectively, which are far higher than the MAR index standard (0.2) and that of mangrove sediment isolates. Furthermore, compared with V. parahaemolyticus isolated from the same mangrove microplastics, Shewanella and V. alginolyticus show stronger drug resistance. It should be noted that there is a closely related relationship between the type of microplastics and the antibiotics resistance of isolated bacteria. For the antibiotics sensitivity test of norfloxacin, streptomycin, amoxicillin, and chloramphenicol, V. parahaemolyticus have the lower antibiotics resistance than that of V. alginolyticus isolated from the same mangrove microplastics. However, Vibrio isolated from PE has stronger antibiotics resistance. Results reveal that mangrove may be one of the potential risks for emergence and spread of bacterial antibiotics-resistant and multidrug-resistant, and microplastic biofilms may act as promoters of bacterial antibiotic resistance.

Fabrication of Homochiral Metal-Organic Frameworks in TiO2 Nanochannels for In Situ Identification of 3,4-Dihydroxyphenylalanine Enantiomers.

Enantioselective identification of chiral molecules is important for biomedical and pharmaceutical research. However, owing to identical molecular formulas and chemical properties of enantiomers, signal transduction and amplification are still the two major challenges in chiral sensing. In this study, we developed an enantioselective membrane by integrating homochiral metal-organic frameworks (MOFs) with nanochannels for the sensitive identification and quantification of chiral compounds. The membrane was designed using a TiO2 nanochannel membrane (TiNM) as the metal ion precursor of MOFs (using MIL-125(Ti)) and incorporating l-glutamine (l-Glu) into the framework of MIL-125(Ti). Using 3,4-dihydroxyphenylalanine (DOPA) as the model analyte, the as-prepared homochiral l-Glu/MIL-125(Ti)/TiNM exhibits a remarkable chiral recognition to d-DOPA than l-DOPA. More importantly, benefiting from the highly enlarged surface area and confinement effect provided by the MOFs-in-nanochannel architecture, the discrimination for chiral recognition is largely amplified through the chelation interaction of Fenton-like activity of Fe3+ onto DOPA. Using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as the substrate, the positively charged ABTS•+ product via Fenton-like reaction induces significant ionic transport changes in nanochannels, which in turn provides information about chiral recognition. This innovative signal amplification strategy on homochiral nanochannels might pave a new way for sensitive monitoring and chiral recognition.

Engineering Homochiral MOFs in TiO2 Nanotubes as Enantioselective Photoelectrochemical Electrode for Chiral Recognition.

Enantioselective sensing of chiral molecules is an important issue for both biomedical research and the pharmaceutical industry. Here, an enantioselective photoelectrochemical (PEC) sensor was constructed by integrating TiO2 nanotubes (NTs) with metal-organic frameworks (MOFs) for the identification of enantiomers. TiO2 NTs prepared by electrochemical anodization can not only be used as the PEC platform but also as the metal-ion precursor to react with terephthalic acid (BDC) to form MIL-125(Ti) in situ. A postsynthetic exchange (PSE) method was used for exchanging the ligand of MIL-125 by 2-aminoterephthalic acid (BDC-NH2) for further functionalization. Homochirality was then successfully introduced into achiral MIL-125-NH2 by postsynthetic modification (PSM) with l-histidine (l-His). The resulting homochiral metal-organic frameworks (MOF)-in-NT architecture exhibits excellent discrimination ability for the chiral recognition of 3,4-dihydroxyphenylalanine (l/d-DOPA) enantiomers. Moreover, by adjusting the charge-carrier separation-induced photocurrent variation mechanism, the as-proposed homochiral PEC electrode exhibits a broad application potential for the discrimination of enantiomers. Because of the construction of binder-free monochiral MOF-in-NT structure directly on a Ti-metal substrate, the valuable feature is that the PEC sensing platform can be used directly, thereby providing a stable, simplified, and low-cost sensing device for the recognition of chiral enantiomers.

Target-Driven Nanozyme Growth in TiO2 Nanochannels for Improving Selectivity in Electrochemical Biosensing.

Nanozymes have been used in colorimetric and electrochemical sensing because of their low cost and high stability. However, the wide applications of nanozymes in sensing devices are largely limited due to their poor selectivity. In this study, unlike traditional methods using prepared nanozymes for target detection, we designed a target-driven nanozyme growth strategy in TiO2 nanochannels to detect analytes. Using telomerase as an example, the established recognition event was used to expand the photocatalytic activity of TiO2 to visible-light region, thus triggering Prussian blue nanoparticle (PBNP) growth in visible light. Benefiting from the peroxidase (POD)-like activity of PBNPs, the uncharged 3,5,3',5'-tetramethylbenzidine (TMB) is oxidized to positively charged oxTMB, which induces significant ionic transport changes in nanochannels, and thus in turn provides information about telomerase activity. Such a nanozyme-triggered sensing system exhibited excellent performance in telomerase detection in urine specimens from patients with bladder cancer. This innovative target-driven signal generation strategy might provide a new method for applying nanozymes in developing sensitive, rapid, and accurate biological sensing systems.