Effect of hydrogen ion implantation on cholesterol sensing using enzyme-free LAPONITE®-montmorillonite electrodes

Abstract

Ion irradiation experiments were performed on LAPONITE®-montmorillonite/indium tin oxide (L-MMT/ITO) films using a 20 keV H₂⁺ ion beam with variable fluence ranging from 10¹² to 10¹⁶ ions per cm², and the electrochemical profiling of these irradiated electrodes was done using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used for pre and post-irradiation morphology study and binding analysis. FTIR spectroscopy indicated the implantation of low-energy H₂⁺ ions resulting in the formation of new bonds. The enhanced cholesterol sensitivity of irradiated films up to a fluence of 10¹³ ions per cm² was observed due to morphological changes taking place in L-MMT films. Close to 20% enhancement in cholesterol sensitivity was noticed, when the ion fluence was ≈10¹³ ions per cm². The sensitivity for cholesterol detection of the L-MMT electrode formed through H₂⁺ ion implantation clearly exhibited a strong dependence on the fluence of the ion beam. The radiation-induced enhanced sensitivity can be proposed as a platform for development of a more effective enzyme-free strip sensor.