Flower-like NiO as an oxidase-like nanozyme for the colorimetric and smartphone-assisted detection of nitrite in food

• Published in: Microchemical journal Vol. 208; p. 112584
• Main Authors: Huang, Yihong, Fu, Ning, Liu, Yujia, Zhang, Hanqiang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2025
• Subjects: Colorimetric detection; Flower-like NiO; Nitrite; Oxidase-like nanozyme; Smartphone; Flower-like NiO; Nitrite; Smartphone; Oxidase-like nanozyme; Colorimetric detection
• DOI: 10.1016/j.microc.2024.112584
• ISSN: 0026-265X

Schematic diagram of colorimetric and smartphone-assisted detection of nitrite in food. [Display omitted] •A simple, rapid, and large-scale method for the synthesis of NiO mimetic oxidase was developed.•The NiO nanozyme exhibits ultrafast catalytic kinetics and long-term catalytic platform.•The NiO nanozyme has a very small kinetic constant (0.0337 mM) for TMB.•Colorimetric and smartphone-assisted methods were developed for NO2− detection.•Good NO2− detection performance in food was achieved. Nitrite (NO2−), a common food preservative and additive, is extensively used in the production of meat products. However, prolonged consumption of NO2− can cause irreparable harm to the human body; therefore, quantitative detection of NO2− in food is essential for the protection of human health. In this study, nickel oxide (NiO) nanomaterials with a distinctive flower-like morphology and large specific surface area (238.5 m2/g) were synthesized in large quantities using a straightforward stirring method. The NiO nanomaterials exhibited oxidase-like catalytic properties, enabling the rapid oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) (in less than 1 min) with long-term catalytic stability (for 30 min). Moreover, the NiO nanomaterials showed remarkable nanozyme activity, with a kinetic constant as low as 0.0337 mM for TMB. Based on changes in absorbance and color induced by the diazotization reaction between NO2− and oxidized TMB, colorimetric and smartphone-assisted identification methods were developed for the quantitative detection of NO2− with broad linear detection ranges and low detection limits. Finally, the two developed methods were used for the detection of NO2− in food samples, achieving similar results and indicating their high accuracy and feasibility.