Development of single-use thin film electrodes based on Zn2SnO4 on In2O3:SnO2 substrates with their biosensing applications

Abstract

Dopamine (DA) has a significant impact on the emergence and treatment of certain diseases (e.g., Alzheimer’s and Parkinson’s diseases). Therefore, monitoring of DA is important, and using biosensors is a favorable option instead of time-consuming and expensive conventional methods. In biosensor manufacturing, thin films have become a rapidly emerging field. In this study, a non-enzymatic electrochemical biosensor based on thin film electrodes is developed for monitoring DA levels. The thin film electrodes (ZTO/ITO) are developed by deposition of Zn 2 SnO 4 (ZTO) on In 2 O 3 :SnO 2 (ITO) substrates by magnetron sputtering. 3-aminopropyltriethoxysilane (APTES) is used to modify the surface of these electrodes. Physical, optical, and structural properties of the electrodes are determined by applying surface profilometry, UV-VIS-NIR spectrophotometry, X-ray diffraction (XRD), and scanning electron microscopy (SEM) measurements. According to these measurements, it has been observed that the ZTO/ITO combination has a higher optical transmission value than the bare ITO, depending on the deposition time and the oxygen concentration used during ZTO deposition. In addition, the ITO thin film has a crystalline structure, while the ZTO thin film has an amorphous structure and both thin films have a good surface morphology. As electrochemical analysis, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) measurements are performed. As a result of CV and EIS measurements, a remarkable change (63.54%) was observed after applying APTES modification onto the surface of ZTO/ITO electrode, and the ones obtained by DPV showed successful detection of DA by APTES modified ZTO/ITO. In addition, the experiments in the presence of interferences such as ascorbic acid (AA), uric acid (UA), bovine serum albumin (BSA), and fish sperm double-stranded DNA (fsDNA) show that the electrodes can be successfully applied for voltammetric determination of DA. The detection limit of DA was estimated to be 0.013 µM in the range of DA between 0.1 – 1 µM, and sensitivity was calculated and found to be 11.057 μA μg −1 mL cm −2 , which means ZTO/ITO electrodes have a good sensitivity. • ZTO/ITO thin film electrodes are fabricated by DC magnetron sputtering. • Surface of the ZTO/ITO electrodes are modified with APTES. • Single-use transparent APTES/ZTO/ITO electrodes are used for voltammetric detection of dopamine (DA). • APTES/ZTO/ITO electrodes have been used for the first time for detection of DA. • APTES/ZTO/ITO electrodes provided a low detection limit and good selectivity on DA detection.