Visible Raman excitation laser induced power and exposure dependent effects in red blood cells

Abstract

We present results of Raman spectroscopic studies carried out on optically trapped red blood cells with Raman excitation wavelength in Q-band region of the hemoglobin (Hb) absorption spectrum. The results obtained suggest that when exposed to the Raman excitation laser the RBCs get deoxygenated due to photo-dissociation of oxygen from hemoglobin. For smaller exposure durations (5 s) the level of deoxygenation increases with an increase in power. However, for longer exposure durations the deoxygenated hemoglobin in the cells gets irreversibly oxidized to form a low spin ferric derivative of hemoglobin. The rate of oxidation depends upon the initial level of deoxygenation; higher the initial level of deoxygenation, higher is the rate of oxidation. However, the RBCs deoxygenated via oxygen deprivation (i.e. N purging) were found to be very stable against any laser induced effect. These observations suggests that in case of laser induced deoxygenation of RBCs the free oxygen generated by photo-dissociation acts as the oxidizing agent and leads to oxidative damage of the RBCs.

Optical tweezers combined with micro‐Raman investigation of alcohol‐induced changes on single, live red blood cells in blood plasma

“…have used this technique to probe the laser power‐induced deoxygenation in RBCs. They have reported the photodissociation of oxygen from hemoglobin in high laser beam power . The possibility of using Raman tweezers setup in forensic applications was also investigated.…”

“…They have reported the photodissociation of oxygen from hemoglobin in high laser beam power. [18] The possibility of using Raman tweezers setup in forensic applications was also investigated. Experiments were performed on both fresh and old blood, where as a decrease in two oxyhemoglobin markers (1,369 and 1,636 cm -1 ) was observed in case of dry blood sample.…”

Raman Spectroscopy of Blood and Blood Components

“…59 Laser tweezers Raman spectroscopy has become an increasingly important technique in the study of living RBCs, for investigations of oxygenation within single cells, [60][61][62] and for investigation of the effects of laser light on RBC biology. [63][64][65] The method has also been integral for characterizing red cell response to stimulus/ stress (e.g., alcohol-induced denaturation, 66 electrical current, 67 oxidative stress, 68 and pH changes 69 ), and has been deployed to compare oxygen uptake of different globin-containing cells. 70 Workers at the Center for Biophotonics, Science and Technology, UC Davis, who contributed to developing the LTRS capability, have studied a number of these phenomena.…”

Development of a flow cell based Raman spectroscopy technique to overcome photodegradation in human blood

“…4(e) and 4(f) which displays the mean of (n = 14 time series) difference spectra between the mean of the first 10 spectra and the last 10 spectra for each time series, along with 95% confidence interval, for static and flowed blood respectively. The longer laser exposure time of 200 s for the static blood volume could be causing photoinduced oxidation in the static blood as shown in previous reports [21,[36][37][38]. In contrast each flowed blood volume is exposed to the focused laser spot for only 0.4 s at the 100 µm depth inside the quartz flow cell.…”

“…There are very small differences noticeable in Fig. 5(a) at 1212, 1224, 1375, 1549, 1604 and 1637 cm 1 which are known to be Raman biomarkers for oxidation [38]. Figure 5(b) is a compilation of Tukey style box plots using this data to show the variation in the ratio of the intensity of Raman bands at: 1212 cm 1 and 1224 cm 1 ; 1340 cm 1 and 1375 cm 1 ; 1549 and 1582 cm 1 ; and 1604 cm 1 and 1637 cm 1 .…”