Synthesis of WO3 nanoparticles for biosensing applications
Abstract Direct electron transfer with redox proteins, in third generation biosensors, is already proved to be favored on electrodes modified with nanoparticles. In this work, different crystallographic and morphologic structures of tungsten oxide (WO3) nanoparticles are modified by hydrothermal synthesis at 180 degC. The electrochemical properties of WO3 nanoparticles deposit on ITO electrodes are investigated and the analytical performance of the nitrite biosensor is presented as proof of concept. Despite the inherent features of each nanostructure, the heterogeneous electron transfer with the WO3 nanoparticles modified electrodes is thoroughly improved and, very importantly, the cytochrome c nitrite reductase (ccNiR) enzyme is able to keep its biological function. When compared with bare commercial ITO electrodes, the exchange rate constant of WO3/ITO electrodes with cytochrome c increased one order of magnitude, while the analytical parameters of the ccNiR/WO3/ITO electrodes response to nitrite (the Michaelis Menten constant is 47 mM and sensitivity of 2143 mA M 1 cm 2) are comparable to those reported for carbon based electrodes. Therefore, these metal oxide nanoparticles are good alternative materials for electrochemical applications, such as non mediated biosensors.