Direct and Label-Free Determination of Human Glycated Hemoglobin Levels Using Bacteriorhodopsin as the Biosensor Transducer

Abstract

Glycated hemoglobin (HbA1c) levels are an important index for the diagnosis and long-term control of diabetes. This study is the first to use a direct and label-free photoelectric biosensor to determine HbA1c using bacteriorhodopsin-embedded purple membranes (PM) as a transducer. A biotinylated PM (b-PM) coated electrode that is layered with protein A-oriented antibodies against hemoglobin (Hb) readily captures non-glycated Hb (HbA0) and generates less photocurrent. The spectra of bacteriorhodopsin and Hb overlap so the photocurrent is reduced because of the partial absorption of the incident light by the captured Hb molecules. Two HbA0 and HbA1c aptasensors that are prepared by conjugating specific aptamers on b-PM coated electrodes single-step detect HbA0 and HbA1c in 15 min, without cross reactivity, with detection limits of ≤0.1 μg/mL and a dynamic range of 0.1–100 μg/mL. Both aptasensors exhibit high selectivity and long-term stability. For the clinical samples, HbA0 concentrations and HbA1c levels that are measured with aptasensors correlate well with total Hb concentrations and the HbA1c levels that are determined using standard methods (correlation gradient = 0.915 ± 0.004 and 0.981 ± 0.001, respectively). The use of these aptasensors for diabetes care is demonstrated.

Adsorption Kinetics of Glycated Hemoglobin on Aptamer Microarrays with Antifouling Surface Modification

“…We note that the K D values found for our engineered GHA immobilized on the Type-1 and Type-2 surfaces are similar to those for gHb-targeted aptamer reported in other works. ,,, However, the K D value for our Type-3 surface, 0.32 nM, is substantially lower than many values reported in literature for gHb-targeted aptamers. − Taken together and in the context of previous literature, our results support the assertion that the inclusion of 11MUA and DMOL surface modifications into aptamer-based SPR biosensing surfaces can improve the inherent specific affinities engineered into aptamers, through their aptamer enhancing and antifouling properties.…”

The Combination Clinical Value of Plasma Brain Natriuretic Peptide and Serum HbAlc in the Diagnosis of Chronic Pulmonary Heart Disease

“…After binding with its receptor, BNP can effectively activate intracellular guanosine cyclase, synthesize cGMP to play biological effects, achieve antidiuretic, inhibit sympathetic nervous activity, reduce pulmonary circulation, inhibit the antirenin angiotensin system, reduce peripheral circulation vascular tension ability, and effectively dilate blood vessels [ 33 ]. BNP has a short half-life and is catabolized by neuronal peptidase.…”

Trends in Quantification of HbA1c Using Electrochemical and Point-of-Care Analyzers

“…Among the various transduction methods, electrochemical sensors are widely employed for analytical applications due to the simple operation, rapid response, cost-effectiveness, portability, and ease of fabrication [ 24 ]. Though there are several reports of HbA1c quantification using optical [ 25 ], photoacoustic [ 26 ], electrochemical piezoelectric [ 27 ], chemiluminescence [ 28 ], photoelectric [ 29 ], magnetic immunoassay [ 30 ], etc., majority of the reports have focused on electrochemical methods of transduction owing to their merits. This review focuses only on the progress in electrochemical strategies for HbA1c measurement.…”

“…The sensor performance was validated using 19 human blood samples and the results showed a good agreement with conventional measurements. The detection time of the sensor is 15 min [ 29 ]. Further fine-tuning of the fabrication parameters are required for reducing the response time to under a minute for applications as a point-of-care diagnostic device.…”