DESIGN AND FABRICATION OF ELECTROCHEMICAL BIOSENSOR BASED ON NANO-GRAPHENE TO DETECT SEROTONIN IN DIABETIC ZEBRA FISH

Background: A novel nanocomposite-modified electrode based on reduced graphene oxide (rGO) decorated with crown-ether and gold nanoparticles (GNPs) on the surface of a glassy carbon electrode (GCE) was fabricated to investigate 5-HT determination. Methods: The morphology of nanocomposite was characterized by scaning electron microscopy (SEM). Diabetic zebrafish was obtained by overfeeding via glucose. 5-HT was successfully determined in the presence of dopamine (DA), ascorbic acid (AA), urea, glucose, and L-tryptophan (L-Trp) by using electrochemical methods. Results: The nanocomposite exhibited satisfactory electrochemical catalytic activity for 5-HT determination using square-wave voltammetry (SWV). The electrochemical behavior of 5-HT at the nanocomposite/GCE displayed reasonable oxidation current and potential. The limit of detection (LOD) of 5-HT obtained from the real samples, containing the control and diabetic group by using the proposed system and HPLC method, was calculated to be about 0.3 and 0.1 µg/L, respectively. The prposed system also demonstrated high selectivity, reasonable sensitivity, and good stability and reproducibility for 5-HT sensing. The nanocomposite was applied for the determination of the biomarker 5-HT in the diabetic and control groups of zebrafish and displayed excellent recoveries about 93 and low relative error about 3% while compared with standard method. Conclusions: It seems that the 5-HT level can be used for earlier diagnosis of diabetes.