Nanostructured Sensors for Non-Enzymatic Detection of Hydrogen Peroxide and Glucose

Abstract

The problem of sensing and detection of small molecules, such as glucose or hydrogen peroxide, is of importance in a variety of areas including fuel cells, energy storage, organic synthesis, wastewater treatment, as well as medical, food or environmental analysis [1]. Although enzymatic sensors of above-mentioned compounds possess high sensitivity, they suffer from instability, complicated modification procedures, and critical microenvironmental factors. Therefore, the development of new simple methods for fabrication of non-enzymatic electrochemical sensors offering good stability and selectivity is highly demanded [2].A large number of electrodes composed of metals (e.g., Au, Ni, Pt, Ru, Co, In, Ir, Cu) and their oxides/hydroxides have been used as enzyme-free electrochemical sensors of glucose and H2O2 [1]. Furthermore, the use of nanomaterials is one of the most promising strategies to replace bulk electrodes because they can decrease the overpotential of reduction/oxidation of many analytes due to the large surface to volume ratio and prolonged entrapment of the analyte in nanostructures electrodes [3]. Nanomaterial-based electrochemical sensors have a great potential to improve both sensitivity and selectivity of sensing devices. This is due to the fact that nanostructures can produce a synergetic effect on catalytic activity, conductivity, and biocompatibility [2].Many efforts have been done to develop non-enzymatic portable sensors for monitoring glucose or hydrogen peroxide. Among others, silver particles [4], silver nanowire arrays [4], copper nanocone arrays [5], and copper oxide/hydroxide nanoflakes/nanowires have been already proposed by our group as enzyme-free electrochemical sensors for detection of these compounds.For the past few years, we have been focused on the synthesis of three types of nanomaterials, i.e., (i) metal nanoparticles, (ii) metal oxide nanostructures, and (iii) template-based metallic nanowires and nanocones. Examples of nanostructures formed by electrodeposition and anodization are shown in Fig. 1. All of these groups of nanomaterials have found applications as enzyme-free, highly-sensitive, and selective sensors for hydrogen peroxide and glucose detection. Therefore, this presentation aims to give a brief overview of the most recent achievements in the synthesis of metallic and oxides nanostructured sensors and their applications. Fig. 1. FE-SEM images of Ag nanoparticles (A), CuO/Cu(OH)2 nanoflakes (B), Ag nanowire arrays (C), and Cu nanocone arrays (D) electrodes obtained by electrodeposition (A, C, D) and anodization (B). Acknowledgements The authors acknowledge Mikołaj Kozak, Milena Kucharska, Anna Brudzisz, Magdalena Jarosz, Elżbieta Kurowska-Tabor, Daria Szeliga, Karolina Gawlak, Marlena Nowak, and Anna Jeleń for their significant contribution to this work. This work was partially supported by National Science Centre, Poland (Project no. 2017/26/M/ST5/00715).