Multifunctional MOF: Cold/hot adapted sustainable oxidase-like MOF nanozyme with ratiometric and color tonality for nitrite ions detection

Integrating multiple functionalities into a single entity is highly important, especially when a broad spectrum of application is required. In the present work, we synthesized a novel manganese-based MOF (denoted as UoZ-6) that functions as a cold/hot-adapted and recyclable oxidase nanozyme (Km 0.085 mM) further developed for ratiometric-based colorimetric and color tonality visual-mode detection of nitrite in water and food. Nitrite ions promote the diazotization process of the oxTMB product, resulting in a decay in the absorbance signal at 652 nm and the emergence of a new signal at 461 nm. The dual-absorbance ratiometric platform for nitrite ion detection functions effectively across a wide temperature range (0 °C to 100 °C), offering a linear detection range of 5–45 μM with a detection limit of 0.15 μM using visual-mode. This approach is sensitive, reliable, and selective, making it effective for detecting nitrite ions in processed meat and water. [Display omitted] •Preparation of multi-functional MOF (UoZ-6) with efficient MOF oxidase activity.•UoZ-6 showed Cold and hot adapted MOF enzyme mimics activity from 0 °C to 100 °C.•UoZ-6 displayed magnetic property and with potential to be re-used up to seven times.•UoZ-6 was used for conventional ratiometric-based colorimetry and color tonality-based visual detection for detection of nitrite in environmental and food samples.