MoS2 nanosheet–Au nanorod hybrids for highly sensitive amperometric detection of H2O2 in living cells

Abstract

MoS₂ nanosheet–Au nanorod (MoS₂–Au) hybrids were utilized to immobilize catalase (CAT) to construct a sensitive hydrogen peroxide (H₂O₂) electrochemical biosensor for the reliable determination of H₂O₂ released from living cells. The fabricated biosensor was characterized by transmission electron microscopy (TEM), UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy, it was observed that the MoS₂–Au hybrid provides excellent matrixes for the adsorption of CAT and the entrapped CAT maintains its native structure and bioactivity. The results of direct electrochemical measurements indicate that on the CAT/MoS₂–Au modified electrode, CAT exhibits a surface controlled and fast electron transfer process towards H₂O₂ reduction. The MoS₂–Au hybrid has a large surface area and provides a biocompatible microenvironment for accelerating direct electron transfer between the enzyme and the electrode. The detection limit of the constructed H₂O₂ biosensor is 1 × 10⁻⁷ M (signal-to-noise = 3) with a wide linear range from 5 × 10⁻⁷ M to 2 × 10⁻⁴ M and a high sensitivity of 187.4 mA M⁻¹ cm⁻². The fabricated H₂O₂ biosensor also exhibits excellent selectivity, good reproducibility and long-time stability. Furthermore, the biosensor was used to perform real-time monitoring of H₂O₂ released from SP2/0 cells, indicating the MoS₂–Au hybrid is an attractive material for application in the efficient immobilization of biomolecules and construction of high-performance biosensors.