Fructosyl valine (Fru-Val) is a glycosylated component of hemoglobin (HbA 1c ) that can serve as a diagnostic target for type 2 diabetes. While average blood glucose levels fluctuate significantly, the more stable levels of HbA 1c can serve as a better long-term diagnostic marker. Here a diagnostic system, incorporating an amperometric method, for detecting Fru-Val (at + 0.1 V vs. Ag/AgCl), using ferrocene boronic acid (FcBA) is presented. FcBA can complex diols, and has easily detectable redox properties. The boronic acid group in FcBA mediates complexation, while the Fe(II)/Fe(III) couple serves as a transducer. The diagnostic system, based on a miniaturized bare glassy carbon paste electrode (GCPE), has a fast response time.

Nearly 200 million people worldwide have type-2 diabetes. Glucose sensors are routinely used for diagnosis; however, the relative amount of glycosylated hemoglobin (HbA1c) may be a better marker. A working electrode made from bare glassy carbon paste was used for sensing fructosyl valine (Fru-Val), a component of HbA1c. Amperometric measurements revealed a linear relationship between Fru-Val concentration and the sensing current. The square correlation coefficient and the sensitivity were 0.999 and 5.26 mA mM À1, respectively. The minimum detection limit was less than 0.05 mM.

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This article reports a new miniature electrochemical detection system integrating a sample pretreatment device for fast detection of glycosylated hemoglobin (HbA 1C ), which is a common indicator for diabetes mellitus. In this system, circular micropumps, normally closed microvalves, dielectrophoretic (DEP) electrodes, and electrochemical sensing electrode are integrated to perform several crucial processes. These processes include separation of red blood cells (RBCs), sample/reagent transportation, mixing, cell lysis, and electrochemical sensing. For the HbA 1C measurement, the RBCs are separated and are collected from whole human blood by using a positive DEP force generated by the DEP electrodes. The collected RBCs are then lysed to release HbA 1C for the subsequent electrochemical detection processes. Experimental data show that the RBCs are successfully separated and are collected using the developed system with a RBCs capture rate of 84.2%. The subsequent detection of HbA 1C is automatically completed by utilizing electrochemical sensing electrode. The microfluidic system only consumes a sample volume of 200 ll. The entire process is automatically performed within a short period of time (10 min). The development of this integrated microfluidic system may be promising for the clinical monitoring of diabetes mellitus.

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