Wearable sweat monitoring of cholesterol using icosahedral hollow PdIr nanocages as highly efficient nanozymes

The ability to monitor cholesterol in biofluids is essential for health management, including the prevention of chronic diseases. Wearable sweat biosensors offer a noninvasive and continuous means of monitoring disease biomarkers, however, the inherently low cholesterol concentration in sweat poses a significant challenge for sensitive detection. In this study, a wearable cholesterol biosensor combining cholesterol oxidase with Pd Ir nanozymes as a cascade sensing unit was developed for continuous monitoring of cholesterol in sweat. The Pd Ir nanozyme, synthesized via seed-mediated growth and selective etching, has a unique icosahedral hollow cage structure and exhibits peroxidase-mimicking activity with catalytic efficiency much higher than its core-shell and natural counterparts. A detection limit of 0.22 μM with a dynamic range of 0–15.5 μM was achieved by the developed cholesterol biosensor in artificial sweat, covering the physiological range in human sweat. Furthermore, the integrated device was validated through volunteer testing after dietary cholesterol intake and exercise, confirming its effectiveness for real-time, dynamic monitoring of sweat cholesterol during daily activities. The wearable sensing strategy based on coupling the nanozyme and enzymes holds great promise for noninvasive and sensitive lipid monitoring and personalized health management across a range of physiological and pathological conditions.