Raman spectroscopy for a rapid diagnosis of sickle cell disease in human blood samples: a preliminary study

Raman spectroscopy has been proposed as a tool for diagnosis of human blood diseases aiming a quick and accurate diagnosis. Sickle cell disease arises in infancy and causes a severe anemia; thus, an early diagnosis may avoid pathological complications such as vasoocclusion, hemolytic anemia, retinopathy, cardiovascular disease, and infections. This work evaluated spectral differences between hemoglobin S (HbS) and hemoglobin A (HbA) to be used in a diagnostic model based on principal components analysis. Blood samples of patients with a previous diagnosis of sickle cell disease were hemolyzed with water, centrifuged, and the pellet was collected with a pipette. Near-infrared Raman spectra (830 nm, 200 mW) were obtained from these samples, and a model based on principal components analysis and Mahalanobis distance were used to discriminate HbA from HbS. Differences were found in the spectra of HbS and HbA, mainly in the 882 and 1,373 cm⁻¹ (valine, HbA) and 1,547 and 1,622 cm⁻¹ (glutamic acid, HbS). The spectral model could correctly discriminate 100 % of the samples in the correspondent groups. Raman spectroscopy was able to detect the subtle changes in the polypeptide chain (valine and glutamic acid substitution) due to the sickle cell disease and could be used to discriminate blood samples with HbS from HbA with minimum sample preparations (hemolysis with water and centrifugation).