Palladium nanoparticles supported on mesoporous silica microspheres for enzyme-free amperometric detection of H2O2 released from living cells

Abstract An enzyme-free sensitive hydrogen peroxide (H 2 O 2 ) amperometric sensor is developed to detect H 2 O 2 released from living cells using palladium nanoparticles supported on sulfonic acid functionalized mesoporous silica microspheres (Pd@SO 3 H-MSM). It is synthesized by an easy and facile method and is subsequently used for fabrication of an electrochemical sensing scaffold via drop-casting modification of a glassy carbon electrode (represented as GC/Pd@SO 3 H-MSM). Comprehensive characterizations including transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis spectrophotometry and electrochemical impedance spectroscopy to confirm the existence and nature of Pd nanoparticles in Pd@SO 3 H-MSM. GC/Pd@SO 3 H-MSM electrode demonstrates electrocatalytic activity for H 2 O 2 reduction in phosphate buffer, leading to a sensitive H 2 O 2 amperometric sensor with wide linear range (47.0 nM-1.0 mM), low detection limit (14.0 nM) and high sensitivity (0.36 μA mM −1  cm -2 ). It exhibits high selectivity, good reproducibility and long-term stability. More importantly, Pd@SO 3 H-MSM exhibits no toxicity to living cells and based on its remarkable analytical advantages, it is further unswervingly used to execute real-time detection of H 2 O 2 released from living tumor cells and healthy normal cells. Thus Pd@SO 3 H-MSM acts as promising material for amperometric determination of H 2 O 2 as well as used to accomplish real-time quantitative detection of H 2 O 2 in biological environment.