MnO2 nanoparticles as tandem nano-enzyme for colorimetric flexible sensor in sweat

The emergence of flexible, painless sensors for biomolecule measurement represents a growing trend in biomedical research. In this context, a highly sensitive flexible sweat sensor, incorporating MnO 2 -TMB@PAM aggregates employing dual-detection routes via visualization and UV–vis spectrometry, has been developed. The sensor utilizes bovine serum albumin (BSA) templated MnO 2 nanoparticles (NPs) as a catalyst for glucose detection. Unlike natural enzymes, this nanozyme is not only cost-effective and stable but also exhibits tandem enzyme-like activities, which facilitates quick and straightforward glucose detection. MnO 2 NPs are synthesized in situ on the surface of polyacrylamide (PAM), ensuring high stability and increasing the contact area of reactors, thereby enhancing the catalytic efficiency of MnO 2 NPs . Additionally, 3,3′,5,5′-tetramethylbenzidine (TMB) is modified on the hydrogel to create an integrated sensing patch (referred to as MnO 2 -TMB@PAM). This patch enables fast and convenient sensing routes, positioning it as a potential candidate for point-of-care testing (POCT) devices. Due to the excellent flexibility and transmittance of PAM , the sensing patch allows for rapid colorimetric analysis of biomolecules such as glucose and dopamine via UV–vis spectrophotometry, as well as visual detection with the naked eyes. Consequently, a high-sensitive, selective, and visually active flexible sensor has been established based on colorimetric and visual methods, facilitating efficient sensing of biomarkers from in vitro biological fluids.