Effect of magneto-thermal conditions on blood viscosity: An experimental study

The effects of the combined magneto-thermal conditions on blood viscosity and the underlying mechanisms of the key factors were elucidated. An integrated magneto-thermal experimental apparatus was devised to measure the viscosity of blood samples sourced from healthy blood donors subject to various non-thermal alternating magnetic fields (AMF), temperature, and magneto-thermal conditions. Mechanisms governing the influence of different factors on blood viscosity were further probed by assessing the viscoelastic modulus of red blood cells (RBCs) and observing RBC morphology. Results show that the hierarchy of significance of three main factors in magnetic hyperthermia on blood viscosity is as follows: temperature > AMF intensity > AMF frequency. Both heightened AMF field strength and elevated temperature led to a nonlinear decrease in blood viscosity, particularly in blood samples with higher hematocrit levels. This is associated with enhanced rheological characteristics of RBCs at increased temperatures and alterations in the repulsive forces between RBCs owing to changes in the cell surface charge induced by AMF. These changes ultimately reduce the flow resistance. However, when the temperature exceeded 46 °C, the deterioration of spectrin on the RBC membrane, coupled with the formation of spicules on the cell membrane surface and subsequent RBC rupture, contributed to increased blood viscosity at higher temperatures.