Electrical and electrochemical strategies for enzyme assay and molecular diagnostics

Abstract

Electrochemical sensing methods have the great potential to achieve simple, sensitive, selective, and cost-effec-tive detection of biomolecules to diagnose and monitor various diseases. In this regard, we have developed DNA and protein diagnostic system based on electrochemical analytical method. In chapter 2, we developed a novel alkaline phosphatase (ALP) determination system based on the $Cu^{2+}$-mediated oxidation which could be detected by impedimetric detection method. It causes change of the interfacial properties of the electrodes and increased interfacial electron-transfer resistance is detected by electrochemical impedance spectroscopy (EIS). In chapter 3, we have developed a novel strategy to achieve label-free multiplex DNA detection system based on the projected capacitive touchscreen. The hybridization event significantly enhanced the capacitance on the electrode, which can be very conveniently detected by the projected capacitive touchscreen. In chapter 4, we developed an electrochem-ical real-time PCR method using aptamer-modified primer. As the elongation is completed including aptamer part at the 5’ end, $Hg^{2+}$ ions are released from the aptamer-modified primers. Since the free ions show higher diffusion rate than the captured ions, the release of $Hg^{2+}$ ions can be measured by squarewave voltammetry (SWV). In chapter 5, we have developed an isothermal real-time nucleic acid amplification monitoring method using aptamer-based RCA. Since the captured ions show lower diffusion rate than the free ions, the binding of $Hg^{2+}$ ions can be measuredby squarewave voltammetry (SWV).