Two-photon probes for Zn²⁺ ions with various dissociation constants. Detection of Zn²⁺ ions in live cells and tissues by two-photon microscopy

A series of Zn²⁺-selective two-photon fluorescent probes (AZnM1-AZnN) that had a wide range of dissociation constants (K_d ^TP=8 nm-12 νM) were synthesized. These probes showed appreciable water solubility (>3 νM), cell permeability, high photostability, pH insensitivity at pH>7, significant two-photon action cross-sections (86-110 GM) upon complexation with Zn²⁺, and can detect the Zn²⁺ ions in HeLa cells and in living tissue slices of rat hippocampal at a depth of >80 νm without mistargeting and photobleaching problems. These probes can potentially find application in the detection of various amounts of Zn ²⁺ ions in live cells and intact tissues. A-tissue a-tissue, we all fall down: A series of Zn²⁺-ion selective two-photon fluorescent probes with a wide range of dissociation constants (K_d^TP=8 nM-12 νM) were developed to be able to detect the Zn²⁺ ions in live cells and intact tissues at a depth of>80 νm without the drawbacks of mistargeting and photobleaching.