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Total antioxidant capacity (TAC) can be evaluated by detecting the content of antioxidants, such as ascorbic acid, based on the enzyme-mimetic activity of nanomaterials. Herein, we fabricated a 3D-V2O5/NC nanocomposite using a self-templating strategy, which achieved ultrafine particles (∼2.5 nm), a porous carbon layer, large specific surface area (152.4 m2/g), N-doping and heterogeneous structure. The strong catalytic activity of 3D-V2O5/NC resulted from the integrated effect between the ultrafine structure of V2O5 nanoparticles and the 3D porous nitrogen-doped carbon framework, effectively increasing the number of active sites. This nanozyme presented a higher catalytic activity than its components or precursors in the nanocomposite (e.g., VN/NC, NC, V2O5, and VO2/g-C3N4). ROS scavenging experiments confirmed that the dual enzyme-like activity of 3D-V2O5/NC (catalase-like and oxidase-like) resulted from their co-participation of ‧O2-, h+ and ‧OH, among which ‧O2- played a crucial role in the catalytic color reaction. By virtue of the 3D-V2O5/NC nanoenzyme activity and TMB as a chromogenic substrate, the mixed system of 3D-V2O5/NC + TMB + H2O2 provided a low detection limit (0.03 μM) and suitable recovery (93.0-109.5%) for AA. Additionally, a smartphone-based colorimetric application was developed employing "Thing Identify" software to evaluate TAC in beverages. The colorimetric sensor and smartphone-detection platform provide a better or comparable analytical performance for TAC assessment in comparison to commercial ABTS test kits. The newly developed smartphone-based colorimetric platform presents several prominent advantageous, such as low cost, simple/rapid operation, and feasibility for outdoor use.

BackgroundThe direct simulation of the γ radiation field in a large space has a very low calculation efficiency.PurposeThis study aims to apply the global variance reduction (GVR) method to the calculation of the γ radiation field in a large space.MethodsFirstly, the volume correction factor was introduced for modifying the lower limit of the weight window wth to address the over-splitting problem caused by the volume difference between the counting cells/grids. The global quality factor (FOMG factor) calculated by the flux-based GVR method using the volume correction was 39 times higher than that obtained by direct simulation. Then, a non-counting area correction method was proposed to address the time-consuming problem encountered in non-counting area calculation while the FOMG factor was further improved by 40%. Finally, based on both the volume correction and non-counting area correction, the calculation of the γ radiation field were compared with that of seven GVR methods based on the particle error, weight, track, number, energy, collision and flux, respectively. The smoothing factor SI was introduced into the flux-based GVR method for results further analysis. [Results and Conclusions] The results show that the FOMG factor calculated by the seven GVR methods is about 2~3 orders of magnitude higher than that obtained by direct simulation, and the standard deviation σ is reduced by 2~3 orders of magnitude. The FOMG factor calculated by the weight-based GVR method is 2 304 times higher than that obtained by direct simulation; this value yields the best variance reduction effect among all GVR methods. As SI increases, the lower limit of the weight window wth of the simulation decreases, and the FOMG factor first increases and then decreases. When SI=0.8, the calculated FOMG factor has the largest value, which is 3 246 times higher than that obtained by direct simulation.

Herein, we fabricated a magnetic 3D nanocomposite based on Co,Ni-codoped and N-modified carbon nanotubes and reduced graphene (CoNi-N-CNTs/rGO). This nanomaterial possessed strong magnetism due to the presence of Co-Ni alloy, abundant defect sites owing to N doping, and a 3D multi-porous structure resulting from CNT in-situ growth on the graphene surface. Based on DFT calculations, H-bonding, hydrophobic and π-π conjugation were inferred to facilitate bisphenol adsorption by nanocomposites, among which π-π interactions provided the greatest adsorption contribution within a given N-doping type. By employing BPM as model compound, the adsorption energies (ΔEa) for π-π conjugation were −1.80, −1.59 and −2.08 eV for graphitic-N, pyridinic-N, and pyrrolic-N, respectively. This infers that pyrrolic-N sites form the strongest BP sorption bonds with the nanocomposite. The nanocomposites were utilized as an extractant in an effervescence tablet-assisted magnetic solid-phase microextraction (ET-MSPE) procedure that was optimized using Plackett-Burman design (PBD) and central composite design (CCD). Under optimized conditions, the ET-MSPE/HPLC-FLD method provided strong analytical performance for quantification of six BPs in juice with limits of detection of 0.06–0.20 μg/L, recoveries of 82.4–103.7 % and RSDs of 1.2–5.3 %. The particular novelty of this study lies in demonstrating the enhancement of adsorption/extraction efficiencies for BPs by nanocomposites resulting from N doping to generate the superior adsorption properties associated with the pyrrolic-N structure. These findings provide a theoretical foundation to inform the rational design of N-doped adsorbents/extractants based on a rigorus understanding of the molecular interactions occurring between carbon-based nanocomposites and BP analogues.

In recent years, high internal phase Pickering emulsions (HIPPEs) has attracted much attention due to its unique organizational properties and has a wide application prospect in the food field. Natural biomacromolecules, active components in organisms, possess good biocompatibility, degradability, no or low toxic effects, which are excellent stabilizers for HIPPEs. In this paper, the potential of natural biomacromolecules to stabilize HIPPEs and recent progress on the application of biopolymer-stabilized HIPPEs in the inhibition of lipid oxidation, as a substitute for trans fatty acids, and in the encapsulation and delivery of nutrients, the 3D printing of foods and encapsulation of probiotics are briefly reviewed in order to provide a reference for the application of HIPPEs stabilized by natural biomacromolecules in foods.

Chitin nanofibers (ChNFs) with both amino and carboxyl groups were obtained by carboxymethylation of partially deacetylated chitin (DE-chitin) with chloroacetic acid. ChNFs could be dispersed again in deionized water after drying and removing the dispersing medium. The aspect ratio of ChNFs had little change before and after dispersion. Further, ChNFs could effectively stabilize oil-in-water (O/W) Pickering emulsions. The emulsion (comprising 10% oil) stabilized with ChNFs at concentrations greater than 0.5% was stabile for 90 days. In addition, ChNFs could stabilize the emulsion in a wide pH range (3–11). Overall, ChNFs is expected to be used as a novel Pickering stabilizer to protect and deliver pH-sensitive active substances in the field of food biology.

Although the previous research confirmed that triclosan (TCS) induced an estrogen effect by acting on a novel G-protein coupled estrogen-membrane receptor (GPER), the underlying mechanisms by which downstream pathways induce neurotoxicity remain unclear after TCS activation of GPER. By employing a series of techniques (Illumina miRNA-seq, RT-qPCR, and artificial intervention of miRNA expression), we screened out four important miRNAs, whose target genes were directly/indirectly involved in neurodevelopment and neurobehavior. Especially, the miR-144 up-regulation caused vascular malformation and severely affected hair-cell development and lateral-line-neuromast formation, thereby causing abnormal motor behavior. After microinjecting 1-2-cell embryos, the similar phenotypic malformations as those induced by TCS were observed, including aberrant neuromast, cuticular-plate development and motor behavior. By KEGG pathway enrichment analysis, these target genes were demonstrated to be mainly related to the PKC/MAPK signaling pathway. When a PKC inhibitor was used to suppress the PKC/MAPK pathway, a substantial alleviation of TCS-induced neurotoxicity was observed. Therefore, TCS acts on GPER to activate the downstream PKC/MAPK signaling pathway, further up-regulating miR-144 expression and causing abnormal modulation of these nerve-related genes to trigger neurodevelopmental toxicity. These findings unravel the molecular mechanisms of TCS-induced neurodegenerative diseases, and offer theoretical guidance for TCS-pollution early warning and management.

We fabricated a novel N,S-co-doped carbon/Co1-xS nanocomposite (NSC/Co1-xS) using a facile sol-gel approach, which featured a multiporous structure, abundant S vacancies and Co-S nanoparticles filling the carbon-layer pores. When the Co1-xS nanoparticles were anchored onto the surface of N,S-co-doped carbon, a synergistic catalysis action occurred. The NSC/Co1-xS nanocomposites possessed both peroxidase-like and oxidase-mimetic dual-enzyme activities, in which the oxidase-mimetic activity dominated. By scavenger capture tests, the nanozyme was demonstrated to catalyze H2O2 to produce h+, •OH and •O2-, among which the strongest and weakest signals were h+ and •OH, respectively. The multi-valence states of Co atoms in the NSC/Co1-xS structure facilitated electronic transfer that enhanced redox reactions, thereby improving the resultant color reaction. Based on the NSC/Co1-xS's enzyme-mimetic catalytic reaction, a visual colorimetric assay and Android "Thing Identify" application (app), installed on a smartphone, offered detection limits of 1.93 and 2.51 mg/dl, respectively, in human serum samples. The selectivity/interference experiments, using fortified macromolecules and metal ions, demonstrated that this sensor had high selectivity and low interference potential for cholesterol analysis. Compared to standard assay kits and previously reported visual detection, the Android smartphone-based assays provided higher accuracy (recoveries up to 93.6-104.1%), feasibility for trace-level detection, and more convenient on-site application for cholesterol assay due to the superior enzymatic activity of NSC/Co1-xS. These compelling performance metrics lead us to posit that the NSC/Co1-xS-based nanozymic sensor offers a promising methodology for several practical applications, such as point-of-care diagnosis and workplace health evaluations.

Herein, we systematically investigated the mechanisms of OH production and arsenic (As(III)) oxidation induced by sulfur vacancy greigite (Fe3S4) under anoxic and oxic conditions. Reactive oxygen species analyses revealed that sulfur vacancy-rich Fe3S4 (SV-rich Fe3S4) activated molecular oxygen to produce hydrogen peroxide (H2O2) via a two-electron reduction pathway under oxic conditions. Subsequently, H2O2 was decomposed to OH via the Fenton reaction. Additionally, H2O was directly oxidized to OH by surface high-valent iron (Fe(IV)) resulting from the abundance of sulfur vacancies in Fe3S4 under anoxic/oxic conditions. These differential OH-generating mechanisms of Fe3S4 resulted in higher OH production of SV-rich Fe3S4 compared to sulfur vacancy-poor Fe3S4 (SV-poor Fe3S4). Moreover, the OH production rate of SV-rich Fe3S4 under oxic conditions (19.3 ± 1.0 μM•h-1) was 1.6 times greater than under anoxic conditions (11.8 ± 0.4 μM•h-1). As(III) removal experiments and X-ray photoelectron spectra (XPS) showed that both OH production pathways were favorable for As(III) oxidation, and a higher concentration of As(V) was immobilized on the surface of SV-rich Fe3S4 under oxic conditions. This study provides new insights concerning OH production and environmental pollutants removal mechanisms on surface defects of Fe3S4 under anoxic and oxic conditions.