A multichromatic colorimetric detection method for Vibrio parahaemolyticus based on Fe ₃ O ₄ -Zn-Mn nanoenzyme and dual substrates

Abstract

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.