Hydrogel Microbead-Confined Nanozyme-SERS Sensor for Robust Detection of Hydrogen Peroxide in Complex Biological Systems.

Inflammation-associated oxidative stress is critically involved in the initiation and progression of numerous pathological processes, yet its reliable detection in complex biological environments remains a major analytical challenge. Herein, we present a hydrogel-confined nanozyme-SERS sensing microbead platform that enables sensitive and interference-resistant detection of H2O2, a central oxidative biomarker of inflammation. Au@Pt nanozymes are encapsulated in poly(ethylene glycol) diacrylate (PEGDA) hydrogel microbeads to form size-selective microreactors with a well-defined reaction microenvironment for direct SERS readout. Within this confined architecture, the Au@Pt nanozymes efficiently catalyze the H2O2-driven oxidation of TMB to a Raman-active product, yielding pronounced signal amplification through the plasmonic Au core. The PEGDA hydrogel matrix permits the rapid diffusion of small molecular reactants while effectively excluding macromolecular interferents, thereby substantially improving signal stability and measurement reproducibility in complex biological matrices. The platform enables H2O2 detection under physiologically relevant conditions, discriminates oxidative signatures among glioma-related cell types, and allows in situ monitoring during murine wound healing. This work establishes a hydrogel-nanozyme analytical paradigm that integrates microenvironment confinement with pore-size-mediated exclusion of macromolecules, providing a generalizable strategy for robust detection of diverse analytes in complex biological systems.