A side-chain engineering strategy for constructing fluorescent dyes with direct and ultrafast self-delivery to living cells.

Organic fluorescent dyes with excellent self-delivery to living cells are always difficult to find due to the limitation of the plasma membrane having rigorous selectivity. Herein, in order to improve the permeability of dyes, we utilize a side-chain engineering strategy (SCES): adjusting the side-chain length of dyes to fine-tune the adsorption and desorption processes on the membrane-aqueous phase interfaces of the outer and inner leaflets of the plasma membrane. For this, a family of fluorescent derivatives () was prepared by functionalizing a styryl-pyridinium fluorophore with alkyl side-chains containing a different carbon number from 1 to 22.