Effect of N-ethylmaleimide, chymotrypsin, and H₂O₂ on the viscoelasticity of human erythrocytes: experimental measurement and theoretical analysis.

The physiological functions of erythrocytes depend critically on their morphology, deformability, and aggregation capability in response to external physical and chemical stimuli. The dynamic deformability can be described in terms of their viscoelasticity. We applied jumping optical tweezers to trap and stretch individual red blood cells (RBCs) to characterize its viscoelasticity in terms of the Young's modulus and viscosity by analyzing the experimental data of dynamic deformation using a 2-parameter Kelvin solid model. The effects of three chemical agents (N-ethylmaleimide, Chymotrypsin, and Hydrogen peroxide) on RBC's mechanical properties were studied by comparing the Young's modulus and viscosity of RBCs with and without these chemical treatments. Although the effects of each of these chemicals on the molecular structures of RBC may not be exclusive, based on the dominant effect of each chemical, we attempted to dissect the main contributions of different constituents of the RBC membrane to its viscosity and elasticity. [GRAPHICS] . A summary of the effects of these three chemical agents on the mean values of E and h (obtained by averaging over 90 RBCs) is shown on a E-eta plane. The lengths of the horizontal and the vertical bars around each point represent the corresponding SEMs of E and eta, respectively.