Peroxidase-AgAu hybrid nanocages as signal transducers for sensitive plasmonic colorimetric sensing

Abstract

In this work, we report a type of highly sensitive signal transducer – HRP-AgAu hybrid cages – for plasmonic colorimetric sensing which was constructed by functionalizing silver–gold nanocages (AgAu cages) with horseradish peroxidase (HRP). The high sensitivity of this signal transducer is ascribed to the fact that the immobilized HRP molecules on the AgAu cage surface can substantially promote the etching of Ag from the cages using H₂O₂ as an etchant, which induces sensitive multicolor changes. Compared to pristine AgAu cages, the HRP-AgAu hybrid cages were over 800 times more sensitive in response to H₂O₂. In addition to high sensitivity, the signal transducer features rapidity, simplicity, and visualization. Moreover, the signal transducer is compatible with the procedures and instruments of existing biosensing technologies, making it straightforward for practical applications. As a proof-of-concept demonstration, we applied the signal transducer in colorimetric sensing of glucose which showed a limit of detection as low as 0.5 μM.