Abstract
This study demonstrates a highly stable, selective and sensitive uric acid (UA) biosensor based on high aspect ratio zinc oxide nanorods (ZNRs) vertical grown on electrode surface via a simple one-step low temperature solution route. Uricase enzyme was immobilized on the ZNRs followed by Nafion covering to fabricate UA sensing electrodes (Nafion/Uricase-ZNRs/Ag). The fabricated electrodes showed enhanced performance with attractive analytical response, such as a high sensitivity of 239.67 μA cm−2 mM−1 in wide-linear range (0.01–4.56 mM), rapid response time (~3 s), low detection limit (5 nM), and low value of apparent Michaelis-Menten constant (Kmapp, 0.025 mM). In addition, selectivity, reproducibility and long-term storage stability of biosensor was also demonstrated. These results can be attributed to the high aspect ratio of vertically grown ZNRs which provides high surface area leading to enhanced enzyme immobilization, high electrocatalytic activity, and direct electron transfer during electrochemical detection of UA. We expect that this biosensor platform will be advantageous to fabricate ultrasensitive, robust, low-cost sensing device for numerous analyte detection.
Highlights
Ref. 33 34 35 36 37 38 39 40 This work nanostructures on electrode surface is needed to keep their morphology, so that same kind of nanostructure can be available in the applications
The vertical growth was further confirmed by cross-sectional analysis of zinc oxide nanorods (ZNRs) grown on Ag electrode (Fig. 1d) which shows ZNRs were relatively well-grown on Ag electrode with ~3.6 μm average length of ZNRs
The aspect ratio of ZNRs was calculated by taking the ratios of average length and average diameter (L/D), which shows as-synthesized ZNRs were of high aspect ratio (~80) that is significantly higher for solution based synthesis method
Summary
Ref. 33 34 35 36 37 38 39 40 This work nanostructures on electrode surface is needed to keep their morphology, so that same kind of nanostructure can be available in the applications. Uniform vertical grown ZnO NRs with high aspect ratio were synthesized via a simple one-step low temperature solution route on a ZnO seeded silver (Ag) electrode surface. The uricase enzyme was immobilized on the ZnO NRs/Ag electrode to fabricate UA sensing device. The biosensor showed enhanced sensing performance for UA detection which can be attributed to the high surface area of vertical grown ZnO NRs leading to abundant enzyme immobilization and direct electron transfer. This sensing system was designed to enable the fabrication of robust, ultrasensitive and highly reproducible UA biosensor device
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