Self-Assembled Triphenylphosphonium-Conjugated Dicyanostilbene Nanoparticles and Their Fluorescence Probes for Reactive Oxygen Species

We report self-assembled novel triphenylphosphonium-conjugated dicyanostilbene-based as selective fluorescence turn-on probes for (1)O(2) and ClO(−). Mono- or di-triphenylphosphonium-conjugated dicyanostilbene derivatives 1 and 2 formed spherical structures with diameters of ca. 27 and 56.5 nm, respectively, through π-π interaction between dicyanostilbene groups. Self-assembled 1 showed strong fluorescent emission upon the addition of (1)O(2) and ClO(−) compared to other ROS (O(2)(−), (•)OH, NO, TBHP, H(2)O(2), GSH), metal ions (K(+), Na(+)), and amino acids (cysteine and histidine). Upon addition of (1)O(2) and ClO(−), the spherical structure of 1 changed to a fiber structure (8-nm wide; 300-nm long). Upon addition of (1)O(2) and ClO(−), the chemical structural conversion of 1 was determined by FAB-Mass, NMR, IR and Zeta potential analysis, and the strong emission of the self-assembled 1 was due to an aggregation-induced emission enhancement. This self-assembled material was the first for selective ROS as a fluorescence turn-on probe. Thus, a nanostructure change-derived turn-on sensing strategy for (1)O(2) or ClO(−) may offer a new approach to developing methods for specific guest molecules in biological and environmental subjects.