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

Alcohol is commonly used as sterilizing agent in hospital settings. Alcohol abuse is also associated with numerous medical complications. It influences the coagulation mechanics and erythropoiesis. Optical tweezers are being extensively used in research labs for the trapping as well as manipulation of biological cells. The biochemical investigation of trapped biological cells can be realized with the integration of Raman spectroscopic technique with optical tweezers, which is termed as Raman tweezers. In this work, we interrogate the influence of ethanol exposure on human red blood cells at single cell level using micro-Raman spectroscopy. In order to mimic in vivo condition to an extent, the experiment is performed by optically trapping the live cell in blood plasma. In the present work, a 785-nm diode laser was used for trapping and probing of single, live red blood cell. An intensity deduction was noted for porphyrin breathing mode at 752 cm^-1 in the Raman spectra as a function of ethanol concentration, which indicates the depletion in hemoglobin. Hemoglobin deoxygenation process in the presence of alcohol is also evident from the variations in major oxygenation marker bands at 1,209; 1,222; 1,544; 1,561 cm^-1, etc., in the Raman spectrum of red blood cell. The effect of alcohol on red blood cells in blood plasma induces membrane depletion and hemoglobin degradation. This is also accompanied by the conversion of oxygenated hemoglobin to more deoxygenated state. Present study has also demonstrated the capability of micro-Raman spectroscopy as a promising tool for probing red blood cell oxygenation status.