This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2019 New J. Chem., 2019, 43, 8651--8659 | 8651 Cite this: New J. Chem., 2019, 43, 8651 Detection of uric acid based on doped ZnO/Ag 2 O/ Co 3 O 4 nanoparticle loaded glassy carbon electrode† M. M. Alam, a Abdullah M. Asiri, bc M. T. Uddin, a M. A. Islam, a Md. Rabiul Awual c and Mohammed M. Rahman * bc A highly sensitive uric acid (UA) sensor was fabricated using a wet-chemical (co-precipitation) method to prepare doped ZnO/Ag 2 O/Co 3 O 4 nanoparticles (NPs) and load them onto a glassy carbon electrode (GCE) by an electrochemical approach. The detailed characterization of the NPs was performed by using conventional methods, such as X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV-vis.), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), Tunneling electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray powder diffraction (XRD) analysis. Thermal gravimetric analysis (TGA) of the as-prepared ternary NPs was performed in order to study the stability of NPs in different temperature ranges over which the weight loss and thermal effect are significant. During the electrochemical analysis, the proposed UA sensor was found to be linear over a large linear dynamic range (LRD; 0.1 nM–0.01 mM). The analytical performance of the sensor such as sensitivity (82.3323 mA mM À1 cm À2 ) was estimated from the slope of the calibration curve and the detection limit (89.14 Æ 4.46 pM) was calculated at a signal to noise ratio of 3. The proposed UA biosensor showed reliable reproducibility, a short response time (22.0 s), long-term stability, and no interference effects. The ZnO/Ag 2 O/Co 3 O 4 NPs/GCE sensor was also validated with real biological samples. Thus, this method might be a prospective and reliable method for the future development of enzyme-free biosensors using doped ternary metal oxides in broad scales. 1. Introduction During purine metabolism in humans, uric acid (UA) is pro- duced and exists in body fluids such as serum and urine. For a healthy life, UA is necessary and the normal level of UA in human serum and urine are 0.13 to 0.46 mM and 2.49 to 4.46 mM, respectively. 1–3 An abnormal level of UA in the human fluid may cause a number of pathological syndromes including high blood pressure, atherosclerosis, gout, Parkinson disease, high blood lipids, kidney and Alzheimer disease. 4–6 A number of researchers have claimed that mental disorders, diabetes and cardiovascular diseases are caused by UA deficiency. 7–10 Similar syndromes like kidney and liver damage, neurological disorders, Parkinson’s and Alzheimer’s diseases are also perceived to be caused by the exposure to various heavy metal ions such as Cu 2+ , Hg 2+ , Pd 2+ , Ln 3+ , Cs 2+ , Ce 3+ and Co 2+ . 11–24 To monitor and control these toxic metal ions, various approaches have been reported. 25–36 Conversely, only a limited number of researches have been reported on the development of UA detection methods including enzymatic methods, 37 electro- chemical methods, 38,39 chemiluminescence 40 and high perfor- mance liquid chromatography. 41,42 Among the detection methods, the electrochemical method is more advantageous and in recent years, a number of researches have been executed to detect numerous chemicals and biochemicals using metal oxides loaded onto a GCE in an electrochemical (I–V methods) approach. 43–50 Nowadays, metal oxides, including transition and semi- conducting metal oxides, have been implemented to detect biochemicals and toxic chemicals. 51–54 The aim of this study is to develop an electrochemical sensor by an electrochemical approach to detect UA using a ternary combination of metal oxides on a GCE. ZnO is a p-type semi-conducting metal oxide with a band gap energy of 3.3 eV and it shows promising a Department of Chemical Engineering and Polymer Science, Shahjalal University of Science and Technology, Sylhet 3100, Bangladesh b Chemistry Department, King Abdulaziz University, Faculty of Science, P. O. Box 80203, Jeddah 21589, Saudi Arabia c Center of Excellence for Advanced Materials Research, Chemistry Department, Faculty of Science, King Abdulaziz University, P. O. Box 80203, Jeddah 21589, Saudi Arabia. E-mail: mmrahman@kau.edu.sa, mmrahmanh@gmail.com; Fax: +966-12-695-2292; Tel: +966-59-642-1830 † Electronic supplementary information (ESI) available. See DOI: 10.1039/ c9nj01287g Received 11th March 2019, Accepted 18th April 2019 DOI: 10.1039/c9nj01287g rsc.li/njc NJC PAPER Published on 03 May 2019. Downloaded by University of Jeddah on 7/10/2020 9:51:39 AM. View Article Online View Journal | View Issue