Direct reduction of HAuCl4 for the visual detection of intracellular hydrogen peroxide based on Au-Pt/SiO2 nanospheres

It is attractive but remains challenging to develop nanomaterials-based methods to realize the colorimetric detection of ultratrace biological analytes. In this work, an HAuCl 4 -H 2 O 2 system was developed for the visual detection of intracellular hydrogen peroxide (H 2 O 2 ) based on the Au-Pt/SiO 2 sensing platform. Owing to their excellent intrinsic peroxidase-like activity, Au-Pt/SiO 2 nanospheres were introduced to catalyze the decomposition of H 2 O 2 and then directly reduce HAuCl 4 into gold nanoparticles (Au NPs) for the naked-eye detection. The produced Au NPs behaved color variations from light purple to wine red as H 2 O 2 concentration increased. Under the optimal conditions, this strategy showed excellent sensitivity for H 2 O 2 with a detection limit of 0.1   nM by naked-eye readout and 0.1 pM by UV–vis spectrometer (S/N   =   3), as well as acceptable selectivity for H 2 O 2 , which could meet the demand for the detection of H 2 O 2 in biological systems. The method was further validated by the determination of H 2 O 2 in HeLa cells with low cellular cytotoxicity. Thus, this strategy would provide simple and sensitive detection of H 2 O 2 in biological systems, revealing the potential application in clinical, biological and environmental researches.