One-pot synthesis of a photostable green fluorescent probe for biological imaging

An excited state intramolecular proton transfer fluorogen, 2-(4-(benzo[d]thiazol-2-yl)-4-hydroxyphenylcarbamoyl) benzoic acid (T4BA), has been synthesized via one-pot reaction for the first time. The cellular imaging effect of T4BA was investigated on human cervical carcinoma cell line HeLa. The fluorescence stability and cellular uptake mechanism of T4BA were also investigated. T4BA exhibits a typical fluorescent characteristic of organic small molecule and the carboxyl group of T4BA can easily form hydrogen bond with the active constituents in cytoplasm which leads to rapid (as quick as 30 s) and selective light-up of the cytoplasm of HeLa cells. Survival rate reached more than 85 % with the cultural concentration up to 100 μM, indicating almost no toxicity of T4BA to the living cells at the working concentration. Results revealed that fluorescence intensity of T4BA decreased less than 10 % after 10 min continuous laser illumination and this dye acts well over a wide pH range, indicating a significant photostability and great potential of it for commercializing as a highly attractive cell imaging agent.