Glycated hemoglobin (HbA(1c)) is one of the most important diagnostic assays for the long-term mark of glycaemic control in diabetes. This study presents an affinity biosensor for HbA(1c) detection which is label-free based on the impedance measurement, and it features low cost, low sample volume, and requires no additional reagent in experiments. The ring-shaped interdigital electrodes (RSIDEs) are designed to promote the distribution uniformity and immobilization efficiency of HbA(1c), and are further employed to characterize the impedance change and identify various concentrations of HbA(1c). The self-assembled monolayer (SAM) of thiophene-3-boronic acid (T3BA) is provided to modify the gold electrode surface. Afterwards, the esterification reaction between HbA(1c), and T3BA produces a relative change of electrical property on the electrode surface. The RSIDEs with SAM of T3BA exhibit a wide range from 100 to 10 ng/mu L., producing an approximate logarithmic decrease of impedance, a low detection limit of 1 ng/mu L, a good selectivity and short-term stability for HbA(1c) determination. The remarkable advantages (miniaturization and low-cost) fill the bill of point-care diagnostics for portable sensor development. (C) 2013 Elsevier B.V. All rights reserved.
