Expanded mesoporous silica-encapsulated ultrasmall Pt nanoclusters as artificial enzymes for tracking hydrogen peroxide secretion from live cells.

Design of synthetic structures that possess the similar functions to natural enzymes held great promise in environmental detection and biomedical application. Herein, a new concept for the fabrication of solid-supported catalysts as peroxidase mimic have been proposed to realize high-catalytic activity and stability by utilizing expanded mesoporous silica (EMSN)-encapsulated Pt nanoclusters. Compared with PtNCs, the introduction of amino group modified EMSN would enrich HO on the surface of PtNCs and increase the catalytic sites for HO decomposition, which gave rise to the higher catalytic activity of EMSN-PtNCs over a broad pH range, especially in weakly acidic and neural solutions. This would facilitate their applications for real-time monitoring the secretion of HO from living cancer cells stimulated by various anticancer drugs. Our findings not only pave the way to use porous matrix as the structural component for the design of the biomimetic catalysts, but also provide a simple and reliable platform to monitor HO released from living cells in real time, which holds great potential for elucidating the biological roles of HO and underlying molecular mechanisms of drug cytotoxicity as well as drug therapeutic effects.