A pH-resistant Zn(ii) sensor derived from 4-aminonaphthalimide: design, synthesis and intracellular applications

Abstract

The development and intracellular applications of a water-soluble Zn(II) sensor (WZS) are described. 4-Aminonaphthalimide is used as the fluorophore of WZS for its high photostability, long excitation and emission wavelength, large Stokes' shift and inert response to pH. N,N-Bis(2-pyridylmethyl)ethylenediamine (BPEN), used as a receptor for Zn(II), is attached to the fluorophore through a rigid benzene framework on the imide moiety. Spectroscopic studies indicate that this fluorophore–receptor linking strategy could be used for the development of effective photoinduced electron transfer (PET) sensors. WZS is pH-insensitive and shows high selectivity for Zn(II) against other biologically relevant metal ions. Cellular applications revealed that WZS could be used for the imaging of intracellular Zn(II).