Hydrophilic Shape‐Memory Nanozyme Aerogel for the Development of a Reusable and Signal‐Amplified Sensor

Abstract Nanozymes hold great promise for biosensing applications, yet their practical implementation is hampered by limitations in signal enhancement, reusability, and device integration. Herein, the development of a hydrophilic shape‐memory nanozyme aerogel that addresses these challenges is reported. The aerogel platform is constructed by embedding chitosan‐protected platinum nanoparticles (Pt‐CS NPs), which exhibit intrinsic peroxidase (POD) activity, within a polyacrylic acid (PAA) aerogel matrix. This hybrid Pt‐CS/PAA aerogel retains the shape‐memory effect of the PAA component as well as the POD activity of the Pt‐CS NPs. Importantly, the aerogel exhibits differential adsorption behaviors toward the two distinct POD oxidation products, oxidized 3,3′,5,5′‐tetramethyl‐benzidine (oxTMB) and oxidized 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (oxABTS), driven by their differing electrostatic potentials with the aerogel. By integrating the shape‐memory effect, nanozyme catalysis, and exceptional probe adsorption performance, the aerogel enables the realization of the signal‐amplified or reusable nanozyme‐based assay, when employing TMB and ABTS as chromogenic substrates, respectively. Furthermore, the aerogel architecture allows for straightforward deviceization, transforming nanozyme‐based analysis from conventional test paper formats into practical, reusable sensing devices. This work establishes a generalizable blueprint for engineering smart nanozyme materials with shape memory characteristics, opening up new avenues for developing advanced biosensing platforms with enhanced performance and user‐friendly operability.