SnO2 nanowires for Electrochemical Detection of Riboflavin
Authors: Arya Sandeep , Singh Anoop , Sharma Asha , Khosla Ajit 
Published: May 2020

Introduction
There are few selected nanomaterials that are being used as base materials in emerging technologies for possessing exceptional potential. Among such materials, tin oxide (SnO2) is a material with exciting sensing properties such as high sensitivity, good chemical stability, high electron mobility, fast response, and good recovery speed [1]. Electrochemical analysis using SnO2 nanomaterial has been used for the qualitative and quantitative determination of amount of electro active analytes. This method is reported to be highly accurate, reliable and cheap. Several characterization techniques are used to investigate the electrochemical response like Cyclic voltammetry (CV), Differential Pulse Voltammetry (DPV), Square Wave Voltammetry (SWV) or Pulsed Amperiometry (PA) [2]. SnO2 nanowires are hereby reported for the detection of Riboflavin (RF). It is observed that the synthesized nanowires can detect the analyte efficiently.

Method

SnO2 nanowires were synthesized by template-directed electrodeposition. Copper foil was used as the substrate. The Sn nanowires were electrodeposited into the nanoholes of the polycarbonate membranes by a three-electrode system in a solution containing 0.05 M SnCl2.2H2O and HCl at room temperature. The electrochemical synthesis was performed on a CHI660 electrochemical Workstation. The electrodeposition was performed at -0.7 V (vs saturated Ag/AgCl), with platinum serving as the counter electrode. After SnO2 nanowires were electrodeposited into track etch polycarbonate membranes, the assembly system was annealed in the air at 85oC to form an ordered SnO2 nanowire array. Ag/AgCl as a reference electrode and gold as an auxillary electrode were used to set up the modifications in detection technique. CV, DPV and EIS techniques were used for the successful detection of RF. Moreover, for measuring the pH values, a pH meter with a combined electrode (glass-reference electrode) was used. All potentials are measured against the Ag/AgCl reference electrode at room temperature.

Results and Conclusions

Field-emission scanning electron microscopy (FE-SEM) is used to characterize the morphologies of the as-prepared products. To demonstrate the chemical composition, EDS analysis was performed. The crystal structure of the as-prepared samples is determined by X-ray diffraction (XRD) with Cu Kα radiation. All these results showed that the nanowires are successfully synthesized in their pure form. Electrochemical studies were carried out by CV and DPV studies. EIS technique also verified about the successful determination of analytes. The developed sensor exhibits good stability, reproducibility and efficiency. Moreover, its practical application was also checked in pharmaceutical samples by the recovery test. For RF content in pharmaceutical samples in the range from 52-150 μM, the developed sensor retains its linearity which indicates that the fabricated sensor not only works well in 0-13 μM range but beyond that range also. Compared with all other existing electrodes reported in the literature, the reported work not only showed remarkably lower detection limit but also the cheapest electrode ever synthesized.

References

[1] Soumen Das, V. Jayaraman, SnO2: A comprehensive review on structures and gas sensors, Progress in Materials Science, 66 (2014) 112–255. doi: 10.1016/j.pmatsci.2014.06.003.
[2] Asha Sharma and Sandeep Arya, Economical and Efficient Electrochemical Sensing of Folic Acid using a Platinum Electrode Modified with Hydrothermally Synthesized Pd and Ag Co-Doped SnO2 Nanoparticles, Journal of The Electrochemical Society, 166 (2019), B1107-B1115. doi: 0.1149/2.0261913jes.