Design and development of fluorescent probe for sugar sensing

Abstract

An aim of this research is to synthesize the fluorescence sensors Cum_B consisting a coumarin as fluorophore and boronic acid as active site and sensor NBDB_AuNPa containing napthalimide as fluorophore, boronic acid as binding site and dopamine as linker. Initially, the complexation properties of sensor Cum_B toward saccharides in DMSO: phosphate buffer pH 7.4 were investigated by fluorescence spectrophotometry. It was that sensor Cum_B showed high selectivity with fructose over other saccharides under PET process and also the log Ks values and detection limit of Cum_B with fructose were 3.6 and 2.83 mM, respectively. For sensor NBDB, it showed a poor fluorescence change and no selectivity with all saccharides. To improve the sensing ability of this sensor, the fabrication of NBDB on AuNPs was performed to improve the significant change of fluorescence. This approach is based on the energy transfer from NBDB to AuNPs resulting in the fluorescence quenching. As anticipated, the suitable saccharides bind to boronic ester to separate NBD and AuNPs inducing fluorescence enhancement of NBD. As a result, fructose was found to induce a large fluorescence enhancement of Cum_B to AuNPs. The sensor NBDB_ AuNPs demonstrates more excellently sensing ability toward fructose than sensor Cum_B with log Ks values of 4.35 and detection limit of 1.50 mM for NBDB_ AuNPs.