Enhancement of electrocatalytic activity in tungsten trioxide nanoparticles by UV-light irradiation: Application for simultaneous detection of tyrosine and tryptophan

Abstract

Electromagnetic radiation is widely used as a tool for grafting or partially modifying materials for specific applications. Here, we demonstrate that the UV-rays irradiation on tungsten trioxide (WO3) nanoparticles, reduces its crystallite size and induces oxygen vacancy, thereby enhancing the catalytic ability significantly. This unique feature of WO3 NPs has been utilised for the development of a novel electrochemical sensor for the simultaneous determination of two important amino acids l-Tyrosine (Tyr) and l-Tryptophan (Trp). Both the Tyr and Trp act as precursors for catecholamine and indolamine neurotransmitters which help neural communication and regulate the psychological, physiological, and behavioural responses in human beings. Therefore, it is important to know the precise amount of these amino acids in the human body fluids, food, and pharmaceutical supplements. Here, we report the fabrication of a simple method for the determination of Tyr and Trp using UV-rays irradiated WO3 nanoparticles modified glassy carbon electrode (GCE) without using any additional surface mediator. Among various exposition times, 4 h irradiated WO3 modified GCE showed an excellent electrocatalytic activity towards the oxidation of Tyr and Trp over wider concentration ranges of 0.01–1100 μM and 0.02–2000 μM for Tyr and Trp with the lowest detection limits of 2.3 nM and 4.4 nM respectively. A good separation in the oxidation potentials was realized during the simultaneous detection of Tyr and Trp from their binary mixture in phosphate buffer saline at pH 6.0. The developed sensor displayed good reproducibility, high sensitivity, and good selectivity towards the determination of the amino acids, making it suitable for the precise determination of Tyr and Trp in farm foods such as milk, curd, and egg.