A series of water-soluble fluorescent probe for viscosity detection and their biological application

Abstract

A series of novel quinoline derivatives L1–L3 with a DπA type were developed as a fluorescent viscosity probe in vitro. L1–L3 displayed very weak emission in nonviscous media and remarkable fluorescence enhancement with the viscosity augment in the water/glycerol system, especially for L2. Different substituent units exhibit a considerable influence on the photophysical properties and response sensitivity of the probes to viscosity. Probes L1–L3 exhibited a direct linear relationship well between log (I/I0) and the log η, which allowed us to quantitatively measure the environmental viscosity. Moreover, L2 modified with 1-butoxy-2-methoxybenzene has been certified to be more sensitive to viscosity because of moderate electron-donating ability. Cell imaging experiments illustrated that L1–L3 is suitable for visualizing the viscosity changes in living cells. As a result, the present work offers a strategy for rationally designing fluorescence probe for viscosity detection in living cells.