A novel quinoline-based two-photonfluorescent probe for detecting Cd2+in vitro and in vivo

Abstract

A new two-photon fluorescent Cd²⁺ probe APQ is developed by introducing a N¹,N¹-dimethyl-N²-(pyridin-2-ylmethyl)ethane-1,2-diamine binding group and a 4-methoxyphenylvinyl conjugation-enhancing group to the 2- and 6-positions of quinoline. This probe shows a large red shift and good emission enhancement under Cd²⁺ binding. It also exhibits a high ion selectivity for Cd²⁺ (especially over Zn²⁺) and a large two-photon absorption cross section at 710 nm. Two-photon microscopy imaging studies reveal that the new probe is non-toxic and cell-permeable and can be used to detect intracellular Cd²⁺ under two-photon excitation.