Nano-enhanced Fenton/Fenton-like chemistry: integrating peroxidase nanozymes, MOFs, and MXenes for next-generation colorimetric biosensors.

Colorimetric biosensors exhibit promising potential toward molecular analysis with a wide range of sample types such as clinical, environmental, animal, and plant samples due to their high portability, sensitivity, specificity, and accuracy. Colorimetric biosensors rely on chromogenic reactions to transduce biochemical signals into visible color changes. Among the various signal transduction mechanisms, the Fenton/Fenton-like reaction is an outstanding reaction that can be used to detect a broad spectrum of analytes under diverse conditions. The ability to detect a wide range of analytes expands the application of the Fenton/Fenton-like reaction; this comes at the cost of specificity. This review highlights how integrating nanomaterials, such as peroxidase nanozymes, metal-organic frameworks (MOFs), and MXenes, can improve conventional Fenton/Fenton-like reactions, significantly enhancing specificity, selectivity, and catalytic efficiency. Besides, we demonstrated that the terms "Fenton/Fenton-like reaction" and "peroxidase-mimic nanozyme activity" fundamentally describe the same catalytic process, providing a unified perspective for researchers in the field. Moreover, the incorporation of MOFs and MXenes offers abundant active sites and enhanced electron transfer, resulting in improved sensitivity and selectivity in Fenton-based colorimetric assays.