Gold nanoparticle assimilated polymer layer on carbon nanotube matrices for sensitive detection of serotonin in presence of dopamine in-vitro

Abstract

A biosensor has been developed based on simple electrodeposition of 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) and gold nanoparticles (nAu) on functionalized carbon nanotube (f-CNT) coated glassy carbon electrode for sensitive detection of an important neurotransmitter, serotonin (5-HT). The glassy carbon electrode was coated with f-CNT, and then deposition of a thin layer of poly-AMT (pAMT) followed by nAu was electrochemically carried out by applying an oxidation potential first and then a reduction potential. The fabricated sensor has been characterized by scanning electron microscopy (SEM) and EDX to realize the sensor system’s surface morphological and chemical properties. Electrochemical responses of serotonin at nAu/pAMT/f-CNT/GCE sensor were investigated by cyclic voltammetry (CV), square wave voltammetry (SWV) and i-t amperometric analysis. The fabricated nAu/pAMT/f-CNT electrode showed high electrocatalytic performance towards the oxidation of 5-HT compared to pAMT/f-CNT and bare GCE, and it exhibited the highest oxidation peak current. At the optimized conditions of SWV, a linear calibration plot was achieved between the peak current against 5-HT concentration, and the detection limit was as low as 7.8 nM. The nAu/pAMT incorporated f-CNT electrode has been investigated for selectivity towards 5-HT in presence of an important electroactive interferent, dopamine (DA). We determined 5-HT from human serum for the practical utility of the sensor and have observed good recovery limits of 96.3 to 103.6 %.