Yushen Liu

A successful development of a dual-substrate colorimetric system for rapid and multicolorimetric semi-quantification of Vibrio parahaemolyticus (V. parahaemolyticus ) has been achieved. The enzymatic activity of Fe ₃ O ₄ -Zn-MnO ₂ -aptamer (Fe ₃ O ₄ -Zn-Mn-Apt) catalysts can induce the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to form oxidized TMB (TMB ⁺ with a bluish green color) and ortho-phenylenediamine (OPD) to form oxidized OPD (with yellow color), resulting in a three-color comparison due to the complementary nature of bluish green and yellow. The absorbance value of TMB ⁺ at 652 nm is used for the determination of V. parahaemolyticus . After optimizing the reaction conditions, the developed dual-substrate colorimetric method exhibits high sensitivity for V. parahaemolyticus detection (limit of detection of 1.12 cfu mL ⁻¹ ) and a linear range of 0–1 × 10 ⁴ cfu mL ⁻¹ ( R ² = 0.9934). Additionally, as the concentration of V. parahaemolyticus increases, the reaction solution changes from bluish green to green and then to yellow, enabling semi-quantitative detection by visual observation with a visual detection limit of 10 cfu mL ⁻¹ . Furthermore, the developed dual-substrate colorimetric method demonstrates excellent selectivity for V. parahaemolyticus detection and satisfactory recovery rates when applied to the determination of V. parahaemolyticus in food samples. IMPORTANCE: The Fe ₃ O ₄ -Zn-Mn nanomimetic enzyme demonstrates significant importance in dual-substrate colorimetric detection for V. parahaemolyticus , owing to its enhanced sensitivity, selectivity, and rapid detection capabilities. Additionally, it offers cost-effectiveness, portability, and the potential for multiplex detection. This innovative approach holds promise for improving the monitoring and control of V. parahaemolyticus infections, thereby contributing to advancements in public health and food safety.

Glucuronoxylans have been considered as an alternative polymer for petroleum polymers in coatings, films, emulsifiers, and other industries. In this study, different molecule weight glucuronoxylans were obtained through xylanase hydrolysis. Dodecenyl succinic anhydride (DDSA) was used as a modifying agent to functionalize glucuronoxylans. At the same degree of substitution (DS), higher molecule weight glucuronoxylans led to better emulsifying properties and emulsion stability. Higher molecule weight DDSA modified glucuronoxylans showed smaller droplets size, lower zeta potential, higher EA (emulsifying activity) and better emulsion stability. These results suggested that molecule weight has positive impact on the emulsifying properties of DDSA modified glucuronoxylans. Furthermore, DS had positive impact on the emulsifying properties of DDSA modified glucuronoxylans.

BACKGROUND: Phenolic endocrine‐disrupting chemicals (EDCs) are widespread and easily ingested through the food chain. They pose a serious threat to human health. Magnetic solid‐phase extraction (MSPE) is an effective sample pre‐treatment technology to determine traces of phenolic EDCs.RESULTS: Magnetic covalent organic framework (COF) (Fe₃O₄@COF) nanospheres were prepared and characterized. The efficient and selective extraction of phenolic EDCs relies on a large specific surface and the inherent porosity of COFs and hydrogen bonding, π–π, and hydrophobic interactions between COF shells and phenolic EDCs. Under optimal conditions, the proposed magnetic solid‐phase extraction‐high‐performance liquid chromatography–ultra violet (MSPE‐HPLC‐UV) based on the metallic covalent organic framework method for phenolic EDCs shows good linearities (0.002–6 μg mL⁻¹), with R² of 0.995 or higher, and low limits of detection (6–1.200 ng mL⁻¹).CONCLUSION: Magnetic covalent organic frameworks (Fe₃O₄@COFs) with good MSPE performance for phenolic EDCs were synthesized by the solvothermal method. The magnetic covalent organic framework‐based MSPE‐HPLC‐UV method was applied successfully to determine phenolic EDCs in beverage and water samples with satisfactory recoveries (90.200%–123%) and relative standard deviations (2.100%–12.100%). © 2023 Society of Chemical Industry.

Staphylococcus aureus (S. aureus) is a pathogen closely associated with foodborne diseases. We prepared a reliable colorimetric sensor to detect S. aureus using click chemical reaction and immunomagnetic separation. Aptamer-functionalized and ALP-labeled Fe₃O₄ NPs act as separation and signal transduction elements. Under the optimized conditions, the Cu⁺ generated by signal transduction triggers a click chemistry reaction, which causes the aggregation of azides and alkyne-AuNPs and a color change. The net extinction ratio of Δ(A₅₃₀/A₇₆₀) was linearly correlated with the S. aureus concentration from 10 to 10⁶ cfu mL⁻¹, and the limit detection was 2.4 cfu mL⁻¹. The recoveries were 91.15 ~ 106.36% for the analysis of spiked food and water samples without pre-enrichment. Therefore, we believe that the detection platform can be easily and accurately used for S. aureus detection, providing a broad prospect for on-site visual detection. Graphical abstract