Featured Application: This biosensor was used for the detection of dopamine without interference from high concentrations (0.5 mM) of ascorbic acid. In addition, the electrode developed in this study presented a great sensitivity (22 nM) and a broad linear range compared with existing electrochemical sensors in the detection of dopamine. Moreover, the analysis of dopamine in physiological samples was examined.Abstract: Tyrosinase, chitosan, and reduced graphene oxide (rGO) are sequentially used to modify a screen-printed carbon electrode (SPCE) for the detection of dopamine (DA), without interference from uric acid (UA) or ascorbic acid (AA). The use of tyrosinase significantly improves the detection's specificity. Cyclic voltammetry (CV) measurements demonstrate the high sensitivity and selectivity of the proposed electrochemical sensors, with detection limits of 22 nM and broad linear ranges of 0.4-8 µM and 40-500 µM. The fabricated tyrosinase/chitosan/rGO/SPCE electrodes achieve satisfactory results when applied to human urine samples, thereby demonstrating their feasibility for analyzing DA in physiological samples.
ZnO thin films were deposited on simple glass substrate by sol-gel technique. The structure, morphology and luminescence of the annealed ZnO thin films were characterized by X-ray diffraction (XRD), atomic force microscope (AFM), ultra-violet spectrometer (UVS) and photoluminescence (PL) spectroscopy, respectively. The XRD experiments shows that all of the samples annealed at 300°C, 400°C, 500°C have a hexagonal wurtzite structure. Absorption spectrum shows that all the samples have high transmittance in the visible range and have a strong absorption near the band edge of ZnO. The morphology of the samples studied by the AFM shows an increase in the annealing temperature causes the surface flatter and the grain size larger. The PL spectrum shows obvious peak near 380nm.
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