Blood analysis by Raman spectroscopy

Abstract

Concentrations of multiple analytes were simultaneously measured in whole blood with clinical accuracy, without sample processing, using near-infrared Raman spectroscopy. Spectra were acquired with an instrument employing nonimaging optics, designed using Monte Carlo simulations of the influence of light-scattering-absorbing blood cells on the excitation and emission of Raman light in turbid medium. Raman spectra were collected from whole blood drawn from 31 individuals. Quantitative predictions of glucose, urea, total protein, albumin, triglycerides, hematocrit, and hemoglobin were made by means of partial least-squares (PLS) analysis with clinically relevant precision (r(2) values >0.93). The similarity of the features of the PLS calibration spectra to those of the respective analyte spectra illustrates that the predictions are based on molecular information carried by the Raman light. This demonstrates the feasibility of using Raman spectroscopy for quantitative measurements of biomolecular contents in highly light-scattering and absorbing media.

Noninvasive Glucose Sensing with Raman Spectroscopy

“…A subsequent whole blood study by Enejder et al 22 in our laboratory confirmed this hypothesis and they were able to demonstrate the feasibility of measuring multiple analytes in 31 whole blood samples with laser intensity and integration time similar to the previously mentioned serum study. 23 A 4X increase in Raman signal collection was achieved by employing a paraboloidal mirror and a shape-transforming fiber bundle for better collection efficiency, as depicted in Figure 5.…”

“…17 With the advent of high quantum efficiency CCD detectors and holographic diffractive optical elements, researchers have increasingly employed CCD-based dispersive spectrometers. 3,[18][19][20][21][22][23][24] The advantages of dispersive NIR Raman spectroscopy are that compact solid-state diode lasers can be used for excitation, the imaging spectrograph can be f-number matched with optical fibers for better throughput, and cooled CCD detectors offer shot-noise limited detection.…”

Optical Investigation of Hematocrit Level in Human Blood

“…The Raman spectroscopy is powerful and versatile technique that enables investigation of molecular composition of human tissues, including measurement of blood parameters [4,8,9]. This method is based on the recording and analysis of light scattered inelastically by the investigated object.…”

“…However, the influence of fluorescence induced by a laser beam, which is usually the strongest for the excitation wavelength range from 270 to 700 nm, must also be taken to account. Commonly used 830 nm laser [4,9], although is good solution when need of reduction of the fluorescence is considered, has also serious drawbacks. Respective Raman signal is generated in a spectral range where sensitivity of CCD arrays is poor as well as absorption of the radiation in water can be serious problem.…”

“…Xu and Chen applied optical coherence tomography for investigating the HCT value [3]. Enejder et al [4] used the Raman spectroscopy and partial least squares (PLS) data analysis for simultaneous measurement of concentrations of multiple analytes in whole blood, including the hematocrit and hemoglobin. There are also works in which authors tried to find correlation between oxygen saturation of whole blood and hematocrit value [5].…”