Siddheswar Maikap
Chang Gung University, Taiwan
Title: Detection of pH/H2O2 and prostrate/breast cancer biomarker by using nickel-oxide/iridium-oxide sensing membrane in electrolyte-insulator-semiconductor structure
Biography
Biography: Siddheswar Maikap
Abstract
Quantification of pH/H2O2 attracts a lot of attentions due to its importance in chemical industries as well as biomedical diagnostic. For the detection of pH and H2O2 by using electrolyte-insulator-semiconductor (EIS) is preferred due to label-free detection, easy fabrication process, and low cost. The NiOx based sensor has shown good pH sensitivity of 50.25 mV/pH. X-ray photo-electron spectroscopy of Ni 2p3/2 has shown two different oxidation states of NiOx membrane and those are Ni2+ and Ni3+ having binding energy 854.5 eV and 856.5 eV, respectively. Existence of these two oxidation states resembles the reduction-oxidation (redox) characteristics of NiOx membrane toward the electroactive species like H2O2. A reference voltage shift of 41 mV is obtained for H2O2 concentration of 10 µM and has shown good linearity up to 100 µM for the first time. In addition, the IrOx membrane shows a record pH sensitivity of 150.4 mV/pH for the first time. This IrOx sensor demonstrated good catalytic behavior as well as the breast cancer biomarker LOXL2 with a concentration of approximately 150 nM is detected. This IrOx nano-net sensor demonstrates good catalytic behavior for H2O2 reduction with a concentration of 100 fM because the oxidation state changes from Ir3+ to Ir4+, whereas a pure SiO2 membrane could not sense H2O2. The oxidation states are confirmed by X-ray photo-electron spectroscopy (XPS). Similarly, prostate cancer is also detected by using NiOx membrane. Therefore, good pH response and redox characteristics of the IrOx/NiOx sensing membrane allow it to diagnosis human disease in future.