An attenuated total reflection (ATR) and Raman spectroscopic investigation into the effects of chloroquine on Plasmodium falciparum-infected red blood cells

Abstract

Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) and Raman spectroscopy were used to compare chloroquine (CQ)-treated and untreated cultured Plasmodium falciparum-infected human red blood cells (iRBCs). The studies were carried out in parallel from the same starting cultures using both spectroscopic techniques, in duplicate. ATR FTIR spectra showed modifications in the heme vibrational bands as well as increases in the CH2/CH3 stretching bands in the 3100-2800 cm(-1) region of CQ-treated iRBCs consistent with an increase in lipid content. Other changes consisted of secondary structural variations including shifts in the amide I and II modes, along with changes in RNA and carbohydrate bands. Raman microspectroscopy of single red blood cells using 532 nm revealed subtle changes in the positions and intensity of ν37 of the core size region marker band and ν4 in the pyrrole ring-stretching region between untreated and CQ-treated iRBCs. Similar patterns in the corresponding relations were also observed in the non-fundamental (overtone region) between the control and treated cells. These differences were consistent with higher levels of oxygenated hemoglobin (oxyHb) in the treated cells as shown in a Principle Component Analysis (PCA) loadings plot. The results obtained demonstrate that vibrational spectroscopic techniques can provide insight into the effect of quinolines on iRBCs and thus may assist understanding the sensitivity and resistance of new and existing anti-malarial drugs.

Single red blood cell analysis reveals elevated hemoglobin in poikilocytes

“…Therefore, oxygenation causes an increase in the intensity of this band. 44 The 1585-cm −1 band assigned to v 37 is larger in the oxygenated state than in the deoxygenated state in RBCs. 44 The 1559-cm −1 band assigned to v 2 only appears in RBCs in arterioles and is absent in venules.…”

“…44 The 1585-cm −1 band assigned to v 37 is larger in the oxygenated state than in the deoxygenated state in RBCs. 44 The 1559-cm −1 band assigned to v 2 only appears in RBCs in arterioles and is absent in venules. 24 The 1372-cm −1 band is the so-called oxidation state marker and appears in the spectra of RBCs in arterioles but is absent in venules.…”

Lymphocytes Studied by Raman Microspectroscopy

“…The explanation of the immunological synapse function, which influences the B cell acquisition of membrane-attached antigens, was explained with the use of three-dimensional confocal microscopy (3D-CM) [5]. Infrared microspectroscopy and Raman microspectroscopy are new methods that give the opportunity to observe human cells, tissues at the molecular level, and give the opportunity to examine physiological and pathological changes [6][7][8][9][10][11][12][13][14][15][16][17]. Revealing even small spectral differences between distinct regions of a cell, vibrational spectroscopy provides considerable potential as a rapid screening method [8,18].…”

Age-Related Changes in FTIR and Raman Spectra of Human Blood

“…One of the important issues in biology could be also solved by spectroscopy -it is the age-related changes of body's indices. Some authors manage to correlate spectral data and the age of donors [10,11]. Agerelated changes were found in UV Raman spectra (amide-I region) of human humerus bone [12].…”