In vivo environmental metabolomic profiling via a novel microextraction fiber unravels sublethal effects of environmental norfloxacin in gut bacteria

Development of a NiFe2O4 covalent organic framework based magnetic solid-phase extraction approach for specific capture of quinolones in animal innards prior to UHPLC-Q-Orbitrap HRMS detection

This study aimed to present a selective and effective method for analyzing quinolones (QNs) in food matrix. Herein, a NiFe2O4-based magnetic sodium disulfonate covalent organic framework (NiFe2O4/COF) was prepared using a simple solvent-free grinding method, and was adopted as a selective adsorbent for magnetic solid phase extraction of QNs. Coupled with UHPLC-Q-Orbitrap HRMS, an efficient method for simultaneous detection of 18 kinds of QNs was established. The method exhibited good linearity (0.01-100 ng g-1), high sensitivity (LODs ranging from 0.0011 to 0.0652 ng g-1) and precision (RSDs below 9.5%). Successful extraction of QNs from liver and kidney samples was achieved with satisfactory recoveries ranging from 82.2% to 108.4%. The abundant sulfonate functional groups on NiFe2O4/COF facilitated strong affinity to QNs through electrostatic and hydrogen bonding interactions. The proposed method provides a new idea for the extraction of contaminants with target selectivity.

Combined effects of norfloxacin and polystyrene nanoparticles on the oxidative stress and gut health of the juvenile horseshoe crab Tachypleus tridentatus

Pollution with anthropogenic contaminants including antibiotics and nanoplastics leads to gradual deterioration of the marine environment, which threatens endangered species such as the horseshoe crab Tachypleus tridentatus. We assessed the potential toxic mechanisms of an antibiotic (norfloxacin, 0, 0.5, 5 μg/L) and polystyrene nanoparticles (104 particles/L) in T. tridentatus using biomarkers of tissue redox status, molting, and gut microbiota. Exposure to single and combined pollutants led to disturbance of redox balance during short-term (7 days) exposure indicated by elevated level of a lipid peroxidation product, malondialdehyde (MDA). After prolonged (14-21 days) exposure, compensatory upregulation of antioxidants (catalase and glutathione but not superoxide dismutase) was observed, and MDA levels returned to the baseline in most experimental exposures. Transcript levels of molting-related genes (ecdysone receptor, retinoic acid X alpha receptor and calmodulin A) and a molecular chaperone (cognate heat shock protein 70) showed weak evidence of response to polystyrene nanoparticles and norfloxacin. The gut microbiota T. tridentatus was altered by exposures to norfloxacin and polystyrene nanoparticles shown by elevated relative abundance of Bacteroidetes. At the functional level, evidence of suppression by norfloxacin and polystyrene nanoparticles was found in multiple intestinal microbiome pathways related to the genetic information processing, metabolism, organismal systems, and environmental information processing. Future studies are needed to assess the physiological and health consequences of microbiome dysbiosis caused by norfloxacin and polystyrene nanoparticles and assist the environmental risk assessment of these pollutants in the wild populations of the horseshoe crabs.

Sea-urchin-like covalent organic framework as solid-phase microextraction fiber coating for sensitive detection of trace pyrethroid insecticides in water

Pyrethroid insecticides residues in water pose a critical threat to the environment from widespread production and overuse. Therefore, it is of major relevance to develop a sensitive and efficient method to detect pyrethroid insecticides in water. In this paper, a covalent organic framework (COF) with NHCO as the structural unit was synthesized using a simple condensation reaction of TTL (NH2) and TDBA (COOH). Various characterization results and density functional theory (DFT) calculations demonstrated that multiple interactions synergistically promoted the adsorption of pyrethroid insecticides on COFTDBA-TTL. Based on the excellent extraction capability of COFTDBA-TTL, efficient detection of 11 pyrethroid insecticides in water was achieved using COFTDBA-TTL-coated SPME fiber and gas chromatography-tandem mass spectrometry (GC-MS). The results showed that the extraction enhancement factors (EFs) of pyrethroid insecticides were as high as 2584-7199, and the extraction efficiencies were 3.28-446 times higher than that of commercial fiber, which reflected its high adsorption property. Meanwhile, the limits of detection (LODs) of the COFTDBA-TTL coated fiber were as low as 0.170-1.68 ng/L under the optimal conditions, and the recoveries of 11 pyrethroid insecticides in the actual water samples were 88.5-108 %. In conclusion, the SPME-GC-MS method based on COFTDBA-TTL coated fiber was simple, rapid, and efficient, and should have a promising application in trace detection of pyrethroid insecticides in the environment.

Toxicity Assessment of Environmental Liquid Crystal Monomers: A Bacteriological Investigation on Escherichia coli and Staphylococcus epidermidis

The widespread existence of liquid crystal monomers (LCMs) in various environmental matrices has been demonstrated, yet studies on the toxicological effects of LCMs are considerably scarce and are urgently needed to be conducted to assess the adverse impacts on ecology and human health. Here, we conducted a bacteriological study on two representative human commensal bacteria, Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis), to investigate the effect of LCMs at human-relevant dosage and maximum environmental concentration on growth, metabolome, enzymatic activity, and mRNA expression. Microbial growth results exhibited that the highest inhibition ratio of LCMs on S. epidermidis reached 33.6% in our set concentration range, while the corresponding data on E. coli was only 14.3%. Additionally, LCMs showed more dose-dependent toxicity to S. epidermidis rather than E. coli. A novel in vivo solid-phase microextraction (SPME) fiber was applied to capture the in vivo metabolites of microorganisms. In vivo metabolomic analyses revealed that dysregulated fatty acid metabolism-related products of both bacteria accounted for >50% of the total number of differential substances, and the results also showed the species-specific and concentration-dependent metabolic dysregulation in LCM-exposed bacteria. The determination of enzymatic activity and mRNA relative expression levels related to oxidative stress confirmed our speculation that the adverse effects were related to the oxidative metabolism of fatty acids. This study complements the gaps in toxicity data for LCMs against bacteria and provides a new and important insight regarding metabolic dysregulation induced by environmental LCMs in human commensal bacteria.

Volatile/semi-volatile metabolites profiling in living vegetables via a novel covalent triazine framework based solid-phase microextraction fiber coupled with GC-QTOF-MS

An in vivo solid-phase microextraction (SPME) fiber with high-coverage capture capacity of plant endogenous substances based on the porous covalent triazine framework (CTF) material was developed. The CTF fiber coupled with gas chromatographic quadrupole time-of-flight mass spectrometer (GC-QTOF-MS) analysis was used for monitoring untargeted endogenous metabolites in living Chinese cabbage plants (Brassica campestris L. ssp. chinensis Makino (var. communis Tsen et Lee)). A total of 100 endogenous substances were identified, mainly including aldehydes, ketones, acids, alcohols, phenols, alkanes, alkenes, esters, isorhodanates, nitriles, as well as indole and its derivatives. Using the in vivo metabolites analysis method, Chinese cabbage plants at different growing stages demonstrated significantly statistical differences in plant metabolism. In addition, metabolic dysregulation of Chinese cabbage plants under fipronil pesticide contamination was observed. To summarize, the proposed approach provides a feasible method to capture metabolic information in living vegetables and for risk assessment of pesticide use during agricultural production.

Battery-Operated and Self-Heating Solid-Phase Microextraction Device for Field Detection and Long-Term Preservation of Mercury in Soil

The application of headspace solid-phase microextraction (HS-SPME) for mercury preservation and detection still has several shortcomings, including the use of high-temperature desorption chamber, the consumption of expensive reagent (NaBEt4 or NaBPr4), and analyte loss during sample storage. Herein, a self-heating HS-SPME device using a gold-coated tungsten (Au@W) fiber was developed for the field detection of mercury in soil by miniature point discharge optical emission spectrometry (μPD-OES). Hg2+ was reduced to Hg0 with NaBH4 solution and then preconcentrated with the Au@W fiber. The adsorbed Hg0 could be rapidly desorbed by directly heating the fiber with a mini lithium battery and subsequently detected by μPD-OES. A limit of detection (LOD) of 0.008 mg kg-1 was obtained with a relative standard deviation (RSD) of 2.4%. The accuracy of the self-heating HS-SPME was evaluated by analyzing a soil certified reference material (CRM) and nine soil samples with satisfactory recoveries (86-111%). Compared to the conventional external heating method, the proposed method reduces desorption time and power consumption from 80 s and 60 W to 20 s and 2.5 W, respectively. Moreover, the self-heating device enables the μPD-OES system to remove the high-temperature desorption chamber, making it more compact and suitable for field analytical chemistry. Interestingly, the Au@W SPME fiber can be also used for the long-term preservation of mercury with a sample loss rate <5% after 30 days of storage at room temperature.