Catecholamine detection by artificial sensors under fluorescence spectrophotometry

Abstract

A goal of this research is to synthesize the chemosensors NB containing a napthalimide and boronic acid group and CC consisting coumarin and 18-crown-6 moieties for detection of catecholamine neurotransmitters. Initially, the complexation properties of sensor NB with biogenic amines in DMSO: phosphate buffer pH 7.4 (1:9) were investigated by fluorescence spectrophotometry. It was found that sensor NB exhibited a fluorescence quenching at 384 nm in the presence of DA and NE under PET process and a large red shift along with the fluorescent enhancement at 475 nm by PCT mechanism for EPI binding. Then, the log Ks values evaluated by fluorescence titration of sensor NB with three catecholamines including DA, NE and EPI were 4.01, 4.08 and 3.00, respectively. The detection limit of sensor NB serves as the catecholamines sensing in a low concentration of micromolar range. Moreover, the combination of two sensing elements NB and CC is capable of classification of DA and NE with dual emission bands under PET mechanism. Interestingly, the dual emission ratio (I475/I384) of NB-DA-CC complex of 4.84 showed a slight larger value than that of NB-NE-CC complex showing 4.28. The PCA analysis was applied to address the effective differentiation of DA and NE. The PCA score plot of both sensors NB and CC toward biogenic amines obviously separated DA and NE in the different quadrant better than a single sensing element in the case of excluding EPI sensing. We have utilized the sensor NB to detect EPI in real biological system of human urine samples. The % recovery for EPI exhibits in the range of 100.14% to 101.06%.