Hydrogel patch doped with nanoenzyme for SERS detection of hydrogen peroxide in complex body fluids.

Abnormally elevated levels of HO in body fluids are strongly correlated with various diseases, particularly cancers. Consequently, there is a significant need to develop a simple and efficient method for direct detection of HO in body fluids. This study presents an economical and feasible hydrogel patch doped with nanoenzyme, specifically gold nanoparticles assembled on the surface of magnetic nanoparticles (Au@FeO NPs), as a sensing platform for HO in complex body fluids. The hydrogel surface-enhanced Raman spectroscopy (SERS) patch demonstrates ultra-high sensitivity for HO in vitro with a detection limit of 10 nM, which is attributed to the excellent catalytic efficiency of Au@FeO NPs and the rich distribution of SERS "hot spots" on the nanoenzyme. Notably, the hydrogel SERS patch exhibits superior specificity, repeatability, and background-free detection of HO in complex body fluids without pre-treatment. Importantly, the HO levels within cancerous cells were observed to gradually increase during the cell death process, as measured using the hydrogel SERS patch developed for practical application. This SERS patch provides a promising, cost-effective strategy for HO detection in complex samples such as body fluids, food, and environmental samples in future applications.