Ligand engineering of luminescent AuAg nanoclusters for targeted mitochondrial and brain imaging

Abstract

Developing luminescent probes for targeted subcellular mitochondrial and in vivo brain imaging is meaningful but very challenging. Herein we report the design of a novel luminescent AuAg nanocluster (NC)-based probe with aggregation-induced emission (AIE) for targeted mitochondrial and brain imaging based on ligand engineering via conjugating (4-carboxybutyl)triphenylphophonium bromide (TPP) on the surface. Upon conjugating TPP with a mitochondria-targeting function, the as-designed AuAg NCs@TPP probe exhibits several merits such as ultrasmall size (<3 nm), strong luminescence with 610 nm emission, long luminescence lifetime (7.193 μs), amphiphilic surface chemistry, and excellent stability, which make it suitable for both targeted mitochondrial imaging and in vivo brain imaging of living mice. In addition, the AuAg NCs@TPP probe has also been demonstrated to have low cytotoxicity and good in vivo biocompatibility, which are helpful for biomedical applications. This study provides a “killing two birds with one stone” strategy for fabricating metal NC-based probes for both mitochondrial and brain imaging, which may stimulate more research activities in the design and biomedical applications of ultrasmall metal NCs.