Power dependent oxygenation state transition of red blood cells in a single beam optical trap

Laser tweezers Raman spectroscopy (LTRS) was used to demonstrate that a red blood cell (RBC) in a single beam optical trap transitions from an oxygenated to a partially deoxygenated state with increasing trapping power. Continuous switching between the two states is possible by repeatedly cycling between low and high trapping powers. Alterations in the hemoglobin conformation and interactions due to cell folding in the trap are proposed to be responsible for the transition. This study demonstrates that mechanically induced biochemical changes by optical forces need to be considered when applying single beam optical tweezers for cell analysis. LTRS holds promise as a functional assay to characterize normal and diseased RBCs based on their biochemical response to the forces of a single beam optical trap. (C) 2011 American Institute of Physics. [doi:10.1063/1.3617467]