Evaluation of Molybdenum as an Electrode Material for Affinity Based Urine Dipstick Biosensing

The work presented in this dissertation focuses on evaluation and characterization of molybdenum (Mo) as an electrode material for affinity based biosensing applications. The material properties of the electrode material dictate the performance of electrochemical biosensors. Mo demonstrates electrochemical properties upon its interaction with electrolytes. Here, we have evaluated the electrochemical properties of Mo for use in affinity based biosensors. Surface characterization of deposited Mo electrode helps us to evaluate the efficiency of fabrication process conditions. The deposition profile of Mo on the flexible polyamide (PA) substrate was characterized through Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques. A label-free immunoassay was designed for detection of target biomolecules. A monolayer of crosslinker was formed on the Mo electrode surface. Thiol and carbodiimide crosslinker chemistries were evaluated with Mo electrode. The characterization of chemical affinity between Mo and crosslinker molecules is required to understand the effectiveness of crosslinker monolayer formation on the electrode surface. The affinity between electrode and crosslinker molecules were characterized through Fourier Transform Infrared Spectroscopy (FTIR), Fluorescence microscopy and X-ray photoelectron spectroscopy (XPS). The binding affinity between antibody and crosslinker molecules was also characterized using FTIR technique. The form factor of the biosensor was modified as a dipstick to detect inflammatory biomarkers namely Interleukin (IL-6) and C-reactive protein (CRP). The effect of variable pH of the synthetic urine on the detection of CRP and Il-6 was evaluated using Electrochemical Impedance Spectroscopy (EIS) technique. The portability of the biosensor was demonstrated using customized electronics hardware assembly. The impedance response from the electronics hardware was compared against standard potentiostat systems.