Synthesis of metal ion-tolerant Mn-doped fluorescence silicon quantum dots with green emission and its application for selective imaging of ·OH in living cells.

Abstract

Monitoring hydroxyl radical (·OH) in living cells remains a big challenge on account of its high reactivity and short half-life. In this work, we designed a fluorescent probe based on manganese-doped silicon quantum dots (Mn-SiQDs) for detecting and imaging of ·OH with good water solubility. The manganese was doped in its ethylene diamine tetra-acetic acid (EDTA) complex form and effectively improved the metal ion tolerance of fluorescence of SiQDs. And m-dihydroxybenzene was used as the reductant to extend the emission of SiQDs to the green region at 515nm when the excitation wavelength was 424nm. Basing on the fluorescence quenching of Mn-SiQDs, a linear response of ·OH was observed in the range 0.8-50μM with alimit of detection (LOD) of 88.4nM, which is lower than thosereported with SiQDs. The interference from other ROS or RNS has been assessed and no impact was found. In fully aqueous systems, the Mn-SiQDs have been applied to monitor and image the endogenous ·OH in HeLa cells. Our work provided a newstrategy for designing SiQDs with good biocompatibility, high selectivity and long monitoringwavelength. Synthesis of green-emitting silicon quantum dots withN-[3 -(trimethoxysilyl) propyl] ethylenediamine (DAMO), Ethylenediamine tetraacetic acid disodium salt dehydrate (EDTA-2Na·2H2O), manganese acetate tetrahydrate (Mn(CH3COO)2·4H20) and m-dihydroxybenzene. The green fluorescence of the silicon quantum dots can be selectively quenched by hydroxyl radicals.