Q-Switched UV Laser Interactions with the Human Blood in Vitro

Abstract

A Q-switched UV laser beam emitting wavelength at 355 nm with different energy densities (fluence, J/cm²) was used for shining sixty human blood samples in vitro. Absorption spectra of hemoglobin were measured for the first time for the samples that exposed to 500 laser pulses in comparison to control samples. It was found that the peak absorbance decreases as the laser fluence increases. This decrease in the peak absorption has been found to be due to the red blood cells deformation and aggregation resulting from the effect of the laser pulses. This phenomenon has been confirmed by examination of the blood cells slides after exposing to the laser radiation. Furthermore, the red blood cells (RBCs) counts were found to be decreased with increasing the laser fluence. The decrease in the RBCs after the irradiation explains the decrease in the hemoglobin absorbance and that represents additional evidence to the structural change according to the optical microscope images. The changes in hemoglobin absorbance are used in a clinically available optical oxymeters. The immediate hematology measurements of the blood samples after the exposure to the laser pulses indicate an increase in the white blood cells (WBCs) of the type basophiles. The measurements were obtained with a significant difference with the level of probability (p≤ 0.05) between the laser exposed samples and the control samples. This laser effect is also due to structural changes in the WBCs. The changes in mitochondria resulting in cells division are in a good agreement with many results in the literature for other types of laser irradiation and other types of the WBCs. The proliferation of the basophiles upon laser photolysis plays a vital role in the activation of the immune system and a consequent destruction of pathogens by these cells.