A new PET fluorescent sensor for Zn2+

A new Zn2+ fluorescent sensor NIDPA, with 1,8-naphthalimide as reporting group and di-2-picolylamine (DPA) as recognizing group, has been synthesized via simple steps. Based on photo-induced electron transfer (PET) mechanism, NIDPA has a five-fold fluorescent enhancement and 10 nm absorption blue-shift under simulated physiological conditions corresponding to the binding of Zn2+. Apparent dissociation constant for Zn2+ (Kd) is 0.83 nM, and Ca2+, Mg2+, Fe2+, Ni2+ and Cr3+have little influence on fluorescent enhancement. These results suggest that NIDPA can be used to quantitatively and selectively measure the concentration of Zn2+ around sub-nanomolar range.