Professor C.C. Liu, Wallace R. Persons Professor of Sensor Technology and Control of Case Western Reserve University, presented “Single-Use Disposable Electrochemical Label-Free Immunosensor for Dectection of Glycated Hemoglobic (HbA1c) Using Differential Pulse Voltammetry” on November 7th, 2016.

 

Abstract:
A single-use disposable in-vitro electrochemical immunosensor for the detection of HbA1c in undiluted human serum using differential pulse voltammetry (DPV) was developed. The biosensor has a three-electrode configuration: 10 nm thin gold film working and counter electrodes and a thick-film printed Ag/AgCl refer-ence electrode which was fabricated on a polyethylene terephthalate (PET) sub-strate. Micro-fabrication techniques including sputtering vapor deposition, laser ablation and thick film printing were used in manufacturing process. This was a roll-to-roll cost effective manufacturing process making the single use, disposa-ble in vitro HbA1c biosensor a reality. Self-assembled monolayers of 3-Mercaptopropionic acid (MPA) was employed to covalently immobilize anti-HbA1c on the surface of gold electrode. A carbodiimide conjugation approach using N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC) and N–hydroxysuccinimide (NHS) was undertaken for cross-linking anti-HbA1c to the carboxylic groups on one end of the MPA. Electrochemical Impedance Spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) confirmed the excellent coverage of MPA-SAM and upward orientation of carboxylic groups. The hindering effect of HbA1c on ferricyanide/ferrocyanide electron transfer reaction was exploited as HbA1c detection mechanism. The biosensor showed a linear range of 7.5-25 μg/mL of HbA1c in 0.1M PBS. Using undiluted human serum as the test medium, the biosensor presented an excellent linear behavior (R2=0.999) in the range of 0.1-0.25 mg/mL of HbA1c. The potential application of this biosensor for in vitro measurement of HbA1c for diabetic management was demonstrated.