Electrochemical Sensing of Uric Acid with Zinc Oxide Nanorods Decorated with Copper Oxide Nanoseeds

Abstract

The use of hybrid nanostructured nanomaterials in sensor development has the potential to overcome the sensitivity issue due to the combination of different nanoscale features of the desired nanomaterials that are accumulated together and offer entirely different characteristics. The sensitive quantification of biomolecules is required for early disease diagnosis. Herein, a hybrid (zinc oxide nanorods modified with copper oxide nanoseeds (ZnO NRs-CuO NSs)) nanostructured nanomaterial-integrated sensor that detects uric acid (UA) is reported. A low-temperature solution-based method was described for ZnO NR and ZnO NR-CuO NS hybrid nanomaterial syntheses. The use of the ZnO NR-CuO NS hybrid nanomaterial resulted in ultra-high sensitivity (1477.88 μA/mM cm 2 ) toward UA detection using the differential pulse voltammetry (DPV) technique. DPV resulted in ∼7.7 times better sensitivity compared to cyclic voltammetry (CV)-measured sensitivity (187.32 μA/mM cm 2 ). The surface modification of ZnO NRs with CuO NS "hybrid nanostructures" showed a significant impact and synergistic effect that enhanced the sensing performance. Furthermore, selectivity, stability, fabrication reproducibility, and applicability in the real sample are other crucial factors of this ZnO NR-CuO NS hybrid nanomaterial-based UA sensor.

Review—Electrochemical Sensing of Uric Acid: Methods and Recent Materials

“…The ZnO NR-CuO NS sensor displayed an LOD of 0.5 μM (S/N = 3). 42 The stable amperometric response in Fig. 5c has a short response time of ∼3 s for reaching the steady state current to sense UA using Nafion/ uricase-ZNRs/Ag electrode.…”

“…41 The CV response current of ZnO NR-CuO NS/GC electrodes were measured in an electrochemical solution of PBS (pH ∼ 7) with K 4 Fe(CN) 6 -K 3 Fe(CN) 6 (1:1; 5 mM) and 100 mM of KCl. 42 The CV graph as displayed in Fig. 1g shows a shift in peak potential as well as an increase in peak redox current.…”

“…The ZnO NRs exhibit R ct ∼ 2200 Ω which is reduced to 980 Ω when it is combines as a hybrid with CuO NS. 42 This reduction in R ct may be due to the morphology where CuO nano sheets are attached to the surface of ZnO nano rods. Also, CuO is a p-type material whereas ZnO is an n-type material.…”

“…The calculated sensitivity and LOD are 1447.9 μAmM −1 cm 2 and 0.28 μM respectively. 42 CuO exhibits a p-type semi conducting nature thereby producing excessive holes which boot the catalytic properties of the sensor. Comparing the sensitivity of ZnO NR-CuO NS modified GCE towards UA via CV and DPV, it can be concluded that DPV technique shows better results with sensitivity almost ∼7.7 times greater than that obtained through CV.…”

“…Figure 1. (a) Cyclic voltammograms of GCE modified with different aerogel materials in 0.1 M KCl at 50 mV s −1 ; 37 (b) The electron-transfer capabilities of electrodes at the scan-rate of 50 mV s −1 during each modification step in 5 mM [Fe(CN) 6 ] 3−/4− containing 0.1 M KCl solution via CV; 38 (c) Cyclic voltammogram of Nafion/Uricase ZNRs/Ag electrode recorded with a scan rate of 100 mV s −1 in the potential range of − 0.1-+ 0.8 V in 0.05 M PBS solution (pH 7.0) without (black line) and with 0.5 and 1.0 mM UA, Inset shows the CV response in only 0.05 M PBS solution (without UA); 39 (d) Cyclic voltammetry curve for Ag/Fe 2 O 3 @PANI modified GCE with different scan rates (from 50-400 mV s −1 ) in the presence of 10 μM of UA (e) the calibration plot for the linear dependence of oxidation and reduction peak current vs square root of scan rate; 40 (f) CV of HADC-BIL electrode in 0.05 mM UA and 0.1 M PBS at different scan rates (20−200 mV s −1 ) (g) with the respective calibration plot of current vs scan rate;41 CV of ZnO NR-CuO NS/GC electrode (h) at different scan rates (i) respective calibrated CV plot 42. …”