Wang Tao, Zhao Gang
Cryo Letters. 2015 May-Jun;36(3):213-20.
Rewarming cryopreserved organs without detrimental damages is a task full of challenging, since devitrification-associated thermal stresses can cause uncontrollable injuries. The ideal rewarming method should obtain a uniform thermal field with a rapid warming rate enough to avoid devitrification. Microwave rewarming is considered to be the most promising method to rewarm cryopreserved organs safely. However, it is difficult to accurately predict the rewarming rates and temperature gradients in cryopreserved organs since the coupling of electromagnetic field and temperature field is changing during microwave rewarming process.
This study is to evaluate the feasibility of microwave rewarming of cryopreserved rabbit kidney embedded with superparamagnetic nanoparticles in a single-mode resonant cavity (434MHz, TE101 mode).
The Finite Element Method (FEM) was used to calculate the coupling of the electromagnetic field and temperature field in a microwave system composed of a rectangular resonant cavity, an antenna source, and a frozen rabbit kidney with temperature-dependent properties. Heat generated by water molecules and nanoparticles in the electromagnetic field of microwave cavity was calculated.
The simulation results showed that, during the rewarming process of the sample phantom without nanoparticles, the rewarming rate was 29.45 degrees C/min and the maximum temperature gradient in the sample was 2.23 degrees C/mm. With nanoparticles embedded in the sample at the same power input to the microwave cavity, the rewarming rate was increased to be 41.38 degrees C/min and the maximum temperature gradient in the sample was 1.93 degrees C/mm.
The study indicates that the use of nanoparticles increases the rewarming rate and temperature uniformity.
在不对冷冻保存的器官造成有害损伤的情况下进行复温是一项极具挑战性的任务，因为与脱玻化相关的热应力可能会导致无法控制的损伤。理想的复温方法应获得均匀的热场，且升温速率要足够快以避免脱玻化。微波复温被认为是安全复温冷冻保存器官最具前景的方法。然而，由于在微波复温过程中电磁场与温度场的耦合不断变化，难以准确预测冷冻保存器官中的复温速率和温度梯度。
本研究旨在评估在单模谐振腔（434MHz，TE101模式）中对嵌入超顺磁性纳米颗粒的冷冻保存兔肾进行微波复温的可行性。
采用有限元方法（FEM）计算由矩形谐振腔、天线源和具有温度依赖性特性的冷冻兔肾组成的微波系统中电磁场与温度场的耦合。计算了微波腔电磁场中水分子和纳米颗粒产生的热量。
模拟结果表明，在无纳米颗粒的样品模型复温过程中，复温速率为29.45℃/min，样品中的最大温度梯度为2.23℃/mm。在向微波腔输入相同功率的情况下，样品中嵌入纳米颗粒时，复温速率提高到41.38℃/min，样品中的最大温度梯度为1.93℃/mm。
该研究表明，使用纳米颗粒可提高复温速率和温度均匀性。
