Boronate-functionalized hydrogel as a novel biosensing interface for the glycated hemoglobin A1c (HbA) based on the competitive binding with signaling glycoprotein.

According to recent increases in public healthcare costs associated with diabetes mellitus, the development of new glycemic monitoring techniques based on the biosensing of glycated hemoglobin A1c (HbA), a promising long-term glycemic biomarker, has become a major challenge. In the development of HbA biosensors for point-of-care applications, the selection of an effective biorecognition layer that provides a high reaction yield and specificity toward HbA is regarded as the most significant issue. To address this, we developed a novel HbA biosensing interfacial material by the integration of boronate hydrogel with glass fiber membrane.

Bioelectrocatalytic detection of glycated hemoglobin (HbA1c) based on the competitive binding of target and signaling glycoproteins to a boronate-modified surface.

We developed an electrochemical glycated hemoglobin (HbA(1c)) biosensor for diagnosing diabetes in whole human blood based on the competitive binding reaction of glycated proteins. Until now, no studies have reported a simple and accurate electrochemical biosensor for the quantification of HbA(1c) in whole blood. This is because it is very difficult to correctly distinguish HbA(1c) from large amounts of hemoglobin and other components in whole blood.

Rheological characteristics of erythrocytes incubated in glucose media.

Glucose-rich plasma is commonly observed in diabetes mellitus and in-vitro incubation of erythrocytes in glucose-rich media may produce the non-enzymatic glycosylation of erythrocyte proteins. The present study investigates the effects of an increased concentration of glucose in a suspending medium on erythrocyte rheological parameters. Erythrocytes, which were obtained from ten healthy volunteers, were washed and incubated in vitro with glucose solutions at different concentrations and incubation times.

Progressive impairment of erythrocyte deformability as indicator of microangiopathy in type 2 diabetes mellitus.

The erythrocyte deformability of blood samples, of diabetes mellitus (DM) patients with and without microangiopathic complications such as nephropathy and retinopathy, is determined and is compared with that of healthy control. The erythrocyte deformability is measured in terms of elongation index (EI) with microfluidic ektacytometer, which is very sensitive to detect changes in EI of erythrocytes due to hyperglycemic process. Each measurement of diffraction pattern of erythrocyte suspension in a highly viscous polyvinyl pyrroridone (PVP) solution in a disposable microchannel is carried out.

Erythrocyte deformability and its variation in diabetes mellitus.

Erythrocyte deformability improves blood flow in the microvessels and in large arteries at high shear rate. The major determinants of RBC deformability include cell geometry, cell shape and internal viscosity (i.e.

Slit-flow ektacytometry: laser diffraction in a slit rheometer.

Background: Deformability of red blood cells (RBCs) is a determinant of blood flow resistance as RBCs pass through small capillaries of the microcirculation. Available techniques for measuring RBC deformability often require a washing process after each measurement, which is not optimal for day-to-day clinical use.

Methods: A laser diffraction technique has been combined with slit-flow rheometry, which shows significant advances in ektacytometric design, operation, and data analysis.

Rapid cell-deformability sensing system based on slit-flow laser diffractometry with decreasing pressure differential.

A slit-flow apparatus with a laser-diffraction method has been developed with significant advances in ektacytometry design, operation and data analysis. In the slit-flow ektacytometry, the deformation of red blood cells subjected to continuously decreasing shear stress in slit-flow can be quickly measured with adopting a laser-diffraction technique. Both the laser-diffraction image and pressure were measured with respect to time, which enable to determine the elongation index (EI) and the shear stress.

Measurement of blood viscosity using a pressure-scanning capillary viscometer.

A newly designed pressure-scanning capillary viscometer is extended to measure the viscosity of whole blood over a range of shear rates without the use of anticoagulants in a clinical setting. In the present study, a single measurement of pressure variation with time replaces the flow rate and pressure drop measurements that are usually required for the operation of a capillary tube viscometer. Using a pressure transducer and capillary, we measured the variation of pressure flowing through capillary tube with respect to time, p(t), from which viscosity and the shear rate were mathematically calculated.

Blood flow resistance with vibration and its effect on blood cell migration.

The present study investigated the effect of transverse vibration on the hemo-rheological characteristics of blood flow using a newly designed pressure-scanning capillary viscometer. As a transverse vibration was applied, aggregated blood cells become disaggregated. Frequency of vibration was found to be the main parameter causing hemo-rheological changes.

Characteristics of blood flow resistance under transverse vibration: red blood cell suspension in Dextran-40.

Vibration under shear flow causes the reduction of flow resistance for shear-thinning fluids. The present study investigates the effect of vibration on the flow resistance of a nonaggregating red blood cell (RBC) suspension with a newly designed pressure-scanning capillary viscometer (PSCV). The PSCV was originally designed to measure non-Newtonian viscosity continuously over a range of shear rates at a time, which was slightly modified and used for the present study.