A FRET assembly of fluorescent gold nanoclusters for ratiometric monitoring peroxynitrite in living cells and zebrafish

摘要

Developing reliable probes for accurate monitoring peroxynitrite (ONOO-) in living systems with high sensitivity and selectivity is imperative for both elucidating its functions in many life-threatening diseases and improving therapeutic interventions. Herein, a novel nano-assembly structure (D-AuGP) was developed by electrostatic interaction-induced assembly between dichromatic gold nanoclusters (Au NCs). The assembly further induced fluorescence resonance energy transfer (FRET) and endowed D-AuGP with a well single-excitation, dual-emission fluorescence characteristic. The prepared nanostructure showed a quantitative ratiometric fluorescence response toward ONOO- with a remarkable decrease of emission peak at 685 nm and a stable peak at 470 nm. A good linear relationship between the ratio of emission intensities at 685 and 470 nm (I685/I470) with ONOO- con-centration in the range of 0-100 mu M was achieved and the limit of detection (LOD) was 0.39 mu M. The possible fluorescence response mechanism was ascribed to the combined effects of dissociation-disturbed FRET and surface structure reconstruction. The Au NCs-based probe was demonstrated to possess high stability, low cytotoxicity, good cell and tissue permeability and high biocompatibility. It was effectively employed for bio-logical imaging and monitoring exogenous and endogenous ONOO- levels in living cells and zebrafish with high contrast.

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