Mechanistic and Fluorometric Investigations of Asparagine Sensing via Catalytic Hydrolysis Mediated by 2D-IMCR for Zn(II)-Bipyridine Nanosheets

Abstract

A novel fluorescence sensor based on 2D ion molecule chelation reaction (2D-IMCR), leveraging the unique coordination chemistry of Zn and 2,2’-bipyridine, has been developed to produce a significant fluorescence quenching response via the strong interaction with L-Asparagine (L-Asp). The importance of asparagine in various metabolic pathways and protein synthesis makes it significantly important as a biomarker and numerous reports indicate the need for its detection. The sensor exhibits an emission peak at 455 nm at an excitation wavelength of 365 nm, providing a robust signal for the detection of L-Asp. The fluorescence quenching mechanism is due to the hydrolysis of L-Asp by Zn(II)-OH species, which are formed by the deprotonation of a Zn(II)-bound water molecule within the Zn-Bpy nanosheets. This Zn(II)-OH species acts as a nucleophile, catalyzing the reaction and producing ammonia, resulting in decreased fluorescence intensity. Remarkably, the developed sensor has a limit of detection of 10.07 nM across a linear range of 20-100 nM. The high selectivity and sensitivity of Zn-Bpy nanosheets to L-Asp when compared to previously developed sensors make it a superior tool for biochemical analysis and diagnostic applications, providing rapid and precise monitoring of L-Asp levels. Furthermore, the novel approach developed in this study emphasizes the potential of metal-ligand complexes in the 2D world in advancing.