Label-free nanostructured sensor for the simple determination of glycosylated hemoglobin (HbA1c)

Abstract

One of the main confirmatory metabolites of diabetes mellitus is known as glycosylated hemoglobin (HbA1c), a hemoglobin modified with cis-diol sugars. This work presents an optical detection of this metabolite via the preparation and characterization of glass surfaces coated with gold nanoparticles (AuNPs) and subsequently modified with boronic acid to enhance specificity. Through the localized surface plasmon resonance intrinsic to the AuNPs an absorbance enhancement (82×) of the Soret band was obtained due to local electric field enhancement. As a consequence, determination of HbA1c can be performed by absorption spectroscopy in the UV–vis range by monitoring the Soret band, at 409 nm. The analytical performance of the label-free, nanostructured sensor is studied using univariate and multivariate calibration. The absorbance dependence of the Soret band as a function of HbA1c concentration showed a linear regression in the clinically relevant range of 0.09–2.35 g/L with a detection limit of 0.03 g/L. The method matches up well analytically when compared to other standard tests and has the advantage of simplicity (sample analysis and signal readout), low cost and fast detection (time of assay completion on the order of 10 s of minutes).