CC BY
15B-P-18
Refractive properties of glycated albumin and hemoglobin in a wide range of wavelengths and temperatures
Ekaterina N.Lazareva1'2 , Andrey Y. Zyubin3, Ilya G. Samusev 3, Valery V. Tuchin 124
1Saratov State University, Saratov, 410012, Russia 2Tomsk State University, Tomsk, 634050, Russia 3Immanuel Kant Baltic Federal University, 236041, Kaliningrad, Russia 4 Lboratory of Laser Diagnostics of Technical and Living Systems, Institute of Precision Mechanics and
Control RAS, Saratov, Russia lazarevaen@list.ru
Most modern diagnostic methods for detecting diabetes mellitus and controlling the degree of its compensation are associated with the determination of fasting blood glucose. Whereas blood, plasma, or serum glucose measurements are short-term and reflect diabetic status over a 24-hour period, glycated protein levels are long-term glycemic indicators.The main glycated blood proteins are glycated hemoglobin HbAlc and glycated albumin. The HbAlc test measures the average blood glucose level over the past 2-3 months in relation to the concentration of hemoglobin (Hb) molecules that have a glucose molecule attached to them [1, 2]. Glycated albumin has been proposed as an additional marker for the control of glycemic status in people with type II diabetes [3]. In vivo, the proportion of glycated albumin in healthy people ranges from 1% to 10% [4], and in the case of diabetes mellitus, this proportion can increase two to three times [5].
Optical research methods occupy a special place and are widely used in the field of medical diagnostics and therapy [6]. Many of the studies demonstrate the possibility of using optical methods for the determination of glycated proteins [7]. In most cases, the application of optical methods requires complex calculations and requires accurate information about optical parameters, such as refractive index, absorption coefficient, scattering coefficient, and others, under various environmental conditions.
This study presents data on the measurement of the refractive index of glycated hemoglobin and glycated albumin in the spectral range of 480-1550 nm at room, physiological and high temperatures. The graphs of dispersion and temperature dependences and comparison with data for non-glycated forms of hemoglobin and albumin are presented.
Basing on the results obtained, we found an increase of the modulus of temperature increment for the glycated form of hemoglobin by an average of (0.34 ± 0.02)x10-4°C1 for the wavelengths 546, 589, and 644 nm. The total derivative of the RI with respect to temperature is related to the effect of thermal expansion and the temperature dependence of the molecular polarizability. In this case, the total polarizability is considered equal to sum of the polarizability of each of molecules. Thus, the molecular complex of hemoglobin with glucose has a larger molecular polarizability and RI depends on the content of charged amino acids in the molecule. The dependence of the RI of dry erythrocytes from diabetic patients on pH (pH = 2-13) and, consequently, on the charge of the protein R-group was shown by Mazarevica et al. by using polarization-sensitive interference microscopy for the wavelength 550 nm[8].
The reported study was funded by RFBR, project number 20-32-90058 and a grant under the Decree of the Government of the Russian Federation No. 220 of 09 April 2010 (Agreement No. 075-15-2021-615 of 04 June 2021).
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[3] Ph. Rondeau, E. Bourdon, "The glycation of albumin: Structural and functional impacts," Biochimie, vol. 93 (2011)
[4] H.V. Roohk, A.R. Zaidi, "A review of glycated albumin as an intermediate glycation index for controlling diabetes," J. Diabet. Sci. Technol., vol. 2 (2008)
[5] E. Bourdon, N. Loreau, D. Blache, "Glucose and free radicals impair the antioxidant properties of serum albumin," FASEB J., vol. 13(1999)
[6] V. V. Tuchin, Tissue Optics: Light Scattering Methods and Instruments for Medical Diagnostics, 3rd ed., PM 254, p. 988, SPIE Press, Bellingham, Washington (2015)
[7]O.A. Smolyanskaya et al., "Multimodal Optical Diagnostics of Glycated Biological Tissues," Biochemistry (Moscow), vol. 84 (1), p. 124-143 (2019)
