Electrocatalytic oxidation of carbohydrates and dopamine in alkaline and neutral medium using CuO nanoplatelets Sathiyanathan Felix a , Pratap Kollu b , Bala P.C. Raghupathy c,⇑ , Soon Kwan Jeong d,⇑ , Andrews Nirmala Grace a,⇑ a Centre for Nanotechnology Research, VIT University, Vellore 632014, Tamil Nadu, India b Thin Film Magnetism Group, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, United Kingdom c Research & Advanced Engineering Division (Materials), Renault Nissan Technology & Business Center India (P) Ltd., Chennai 603002, India d Climate Change Technology Research Division, Korea Institute of Energy Research, Yuseong-gu, Daejeon 305-343, South Korea article info Article history: Received 9 September 2014 Received in revised form 4 December 2014 Accepted 5 December 2014 Available online 13 December 2014 Keywords: Copper oxide Carbohydrates Dopamine Electro-oxidation Nanoplatelets abstract Platelet-like copper oxide nanostructures were prepared by a hydrothermal method. Various techniques like X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) were used to characterize the structure and morphology of the as-prepared products. The electrocatalytic oxidation of carbohydrates and dopamine on the surface of the modified electrode were studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chrono- amperometry (CA). Under the optimal experimental condition, the CuO nanoplatelets (CuO NPlts) loaded on glassy carbon electrode (GCE) exhibited excellent sensitivity in the linear concentration range of carbohydrates, good stability and reproducibility. Interferences from other biological compounds were studied and results indicated good selectivity for glucose, sucrose, and fructose. Apart from the detection of carbohydrates, the electrode was tested for detection possibility of dopamine in the range of 10–80 lM in phosphate buffer solution (PBS) with a detection limit of 8.25 lM. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction Carbohydrates are the most abundant class of organic com- pounds in living organisms. So, much attention has been focused on developing a fast, low cost and high sensitive technique to mon- itor the carbohydrates in diverse fields, ranging from biological process [1], medical diagnostics [2], and food industries [3] to eco- logical applications of industrial waste water treatment [4]. There are now so many methods to measure the carbohydrate concentra- tions, such as liquid chromatography [5], Raman spectroscopy [6], capillary electrophorolysis [7], colorimetry [8], electrochemical technique [9] and so forth. Compared to all these techniques, the electrochemical approach has attracted significant attention and is promising due its simplicity, high sensitivity and possibility of continuous detection of analyte [10]. Electrochemical sensors are divided into conductometric, potentiometric and amperometric biosensors. Among these, amperometric sensors have been used in diverse areas due to its capability to directly transduce the rate of reaction to current [11]. Electrochemical detection of glucose is classified into two groups. One is enzyme glucose oxidase (GOx) based biosensor, which is widely used to detect glucose because of its high selectivity, wherein enzyme oxidizes the glucose to glucolactone and reduces oxygen to hydrogen peroxide [12]. Gen- erally, the detection based on this type of sensor depends on the response from the oxidation of H 2 O 2 or reduction of O 2 . Moreover, the activity of the sensor was easily affected by factors like humid- ity, temperature, pH and toxic chemicals [13]. In other case non- enzymatic sensor (without use of enzymes) the majority of these sensors rely on the current response of glucose oxidation directly at the electrode surface. For the oxidation of carbohydrates, the electrode based on oxide materials are suitable since the analyte of interest gets easily absorbed on the oxide layer through the for- mation of hydrogen bonds via OH  groups, which improves elec- tron transfer [14,15]. Numerous noble metals (e.g. Pd [16], Pt [17], Au [18]) and alloys (e.g. Pt–Pd [19], CuO–TiO 2 [20]) have been investigated in the development of effective non-enzymatic glucose sensors. Though, these nanomaterials show good electrochemical activity towards glucose oxidation, they were easily fouled by the chemisorbed intermediates, which block the electrocatalysts surface and absorbed chlorine ions that caused a hindrance in good operational http://dx.doi.org/10.1016/j.jelechem.2014.12.006 1572-6657/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding authors. Tel.: +91 416 2202412, +82 42 860 3367; fax: +91 416 2243092, +82 42 860 3134. E-mail addresses: balapraveen2000@yahoo.com (B.P.C. Raghupathy), jeongsk@kier.re.kr (S.K. Jeong), anirmalagrace@vit.ac.in (A.N. Grace). Journal of Electroanalytical Chemistry 739 (2015) 1–9 Contents lists available at ScienceDirect Journal of Electroanalytical Chemistry journal homepage: www.elsevier.com/locate/jelechem