热疗用葡聚糖磁流体的升温特性研究

Study on Heating Properties of Water-based Dextran-coated Magnetic Fluid for Hyperthermia

用不同浓度的葡聚糖40000和20000水溶液制备纳米铁氧体磁流体,检测磁流体在交变磁场中的升温情况,计算升温速率和特异性吸收值(SAR值)。结果显示,磁流体在磁场中的升温速率与铁氧体的浓度和磁场强度成正线性相关。磁场强度一定时,磁流体的SAR值与铁氧体浓度成负线性相关;铁氧体浓度一定时,磁流体的SAR值与磁场强度成正线性相关。磁流体的升温速率和SAR值与葡聚糖相对分子质量和浓度无关。瘤内及瘤周注射24.16 mg/0.2 mL磁流体在55 kHz,20kA/m磁场中作用10 min,移值瘤中心的平均升温速率为1.5°C/min,温度可以达到并维持在46°C左右,而注射相同体积生理盐水的移植瘤,温度几乎没有变化。

Water-based magnetic fluids were prepared by using dextran 40000 and 20000 solution of different concentrations as coating agents. The temperature of the magnetic fluid under alternating magnetic field was detected, then, the heating rate and specific absorption rate（SAR） were calculated. It was found that the heating rates of the magnetic fluids were in direct linear proportion to the density of magnetic field and concentration of particles, however, the SAR of the magnetic fluids were in direct linear proportion to the density of magnetic field and in inverse linear proportion to the concentration of particles. Not only the heating rate but also the SAR were independent of the relative molecular mass and concentration of dextran. Being dealt with 55 kHz, 20 kA/m magnetic field for 10 min, the temperature of center of the grafted tumor infiltrated with 24.16 mg/0.2 mL fluid was elevating at 1.5 ℃/min and it could be raised to about 46℃ and retained this level, whereas the temperature in the tumor injected with the same volume of physiological saline was almost unchanged.