Organic Nanoprobe Cocktails for Multilocal and Multicolor Fluorescence Imaging of Reactive Oxygen Species

Hypochlorite (ClO⁻) as a highly reactive oxygen species not only acts as a powerful “guarder” in innate host defense but also regulates inflammation-related pathological conditions. Despite the availability of fluorescence probes for detection of ClO⁻ in cells, most of them can only detect ClO⁻ in single cellular organelle, limiting the capability to fully elucidate the synergistic effect of different organelles on the generation of ClO⁻. This study proposes a nanoprobe cocktail approach for multicolor and multiorganelle imaging of ClO⁻ in cells. Two semiconducting oligomers with different π-conjugation length are synthesized, both of which contain phenothiazine to specifically react with ClO⁻ but show different fluorescent color responses. These sensing components are self-assembled into the nanoprobes with the ability to target cellular lysosome and mitochondria, respectively. The mixture of these nanoprobes forms a nano-cocktail that allows for simultaneous imaging of elevated level of ClO⁻ in lysosome and mitochondria according to fluorescence color variations under selective excitation of each nanoprobe. Thus, this study provides a general concept to design probe cocktails for multilocal and multicolor imaging.