Nanostructured ZnO Interfaces for Highly Sensitive and Selective Dopamine Sensing
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A tyrosinase-functionalized electrochemical biosensor based on vertically aligned ZnO nanorods (NRs) wasdeveloped for the selective and sensitive detection of dopamine. The sensor architecture features an Au working electrode modifiedwith ZnO NRs, followed by sequential surface treatments using tetraethyl orthosilicate, 3-aminopropyl triethoxysilane, andglutaraldehyde to immobilize tyrosinase. Structural and chemical modifications were confirmed via scanning electron microscopy,energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. Chronoamperometric measurementsdemonstrated a significant enhancement in sensing performance for the ZnO NRs-based sensor (3.6114 nA/μM) compared to aplanar ZnO thin-film electrode (0.4318 nA/μM), with a nine-fold increase in sensitivity attributed to the larger enzyme loading areaprovided by the three-dimensional nanostructure. The sensor exhibited excellent linearity and a pronounced response at a lowoperating potential of -250 mV. Interference studies with ascorbic acid and norepinephrine confirmed high selectivity towarddopamine. These findings underscore the utility of nanostructured ZnO interfaces in advancing enzyme-based electrochemicalbiosensing platforms for neurotransmitter detection under physiologically relevant conditions
Abstract
A tyrosinase-functionalized electrochemical biosensor based on vertically aligned ZnO nanorods (NRs) wasdeveloped for the selective and sensitive detection of dopamine. The sensor architecture features an Au working electrode modifiedwith ZnO NRs, followed by sequential surface treatments using tetraethyl orthosilicate, 3-aminopropyl triethoxysilane, andglutaraldehyde to immobilize tyrosinase. Structural and chemical modifications were confirmed via scanning electron microscopy,energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. Chronoamperometric measurementsdemonstrated a significant enhancement in sensing performance for the ZnO NRs-based sensor (3.6114 nA/μM) compared to aplanar ZnO thin-film electrode (0.4318 nA/μM), with a nine-fold increase in sensitivity attributed to the larger enzyme loading areaprovided by the three-dimensional nanostructure. The sensor exhibited excellent linearity and a pronounced response at a lowoperating potential of -250 mV. Interference studies with ascorbic acid and norepinephrine confirmed high selectivity towarddopamine. These findings underscore the utility of nanostructured ZnO interfaces in advancing enzyme-based electrochemicalbiosensing platforms for neurotransmitter detection under physiologically relevant conditions