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

An enzyme-free sensitive hydrogen peroxide (H2O2) amperometric sensor is developed to detect H2O2 released from living cells using palladium nanoparticles supported on sulfonic acid functionalized mesoporous silica microspheres (Pd@SO3H-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@SO3H-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@SO3H-MSM. GC/Pd@SO3H-MSM electrode demonstrates electrocatalytic activity for H2O2 reduction in phosphate buffer, leading to a sensitive H2O2 amperometric sensor with wide linear range (47.0 nM-1.0 mM), low detection limit (14.0 nM) and high sensitivity (0.36 mu A mM(-1) cm(-2)). It exhibits high selectivity, good reproducibility and long-term stability. More importantly, Pd@SO3H-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 H2O2 released from living tumor cells and healthy normal cells. Thus Pd@SO3H-MSM acts as promising material for amperometric determination of H2O2 as well as used to accomplish real-time quantitative detection of H2O2 in biological environment.