Glycated Albumin Measurement Using an Electrochemical Aptasensor for Screening and Monitoring of Diabetes Mellitus

Glycated albumin (GHSA) is a medium-term glycaemic control marker of diabetes, which can be used as an alternative to or together with glycated haemoglobin (HbA1c). Currently available methods for the measurement of GHSA are limited in clinical practice because they involve slow and cumbersome processes of sample preparation, proteolytic digestion, and thermal incubation, and they suffer from limited analytical performance, and/or a lack of normalization to total albumin (HSA) levels. In this paper, we developed a simple electrochemical biosensor to measure GHSA values based on two DNA aptamers that specifically bind to GHSA and HSA. We used square wave voltammetry (SWV) to measure binding of the target proteins to their specific biotinylated aptamers, which had been immobilised on separate streptavidin (STR)-modified screen-printed carbon electrodes (SPCEs), in the presence of the redox mediator ferricyanide (Fe(CN)(6)(3-)). This electrochemical aptasensing system had a detection limit of 3 ng/ml for GHSA and 0.2 mu g/ml for HSA. The results exhibited high selectivity for GHSA over other molecules present in the blood. The developed sensor was able to measure the amount of GHSA in plasma samples. A statistically significant difference was observed in the elevated plasma GHSA levels in diabetic versus non-diabetic patients. Moreover, the trends in these GHSA levels were consistent with those obtained using the HbA1c test. The sensing system reported herein could be applied as a point-of-care-testing (POCT) device for measurements of clinically relevant GHSA values.