Biomechanics Group, Institute for Bio-Economy and Agri-Technology, Centre for Research and Technology Hellas (CERTH), 38333 Volos, Greece.
Department of Mechanical Engineering, University of West Attica, 12210 Athens, Greece.
Comput Methods Programs Biomed. 2019 Apr;172:79-85. doi: 10.1016/j.cmpb.2019.02.008. Epub 2019 Feb 13.
The present study deals with the hyperthermia therapy, which is the type of treatment in which tissues are exposed to high temperatures in order to destroy cancer cells with minimal injury to healthy tissues. In particular, it focuses on glioblastoma multiform, which is the most aggressive cancer that begins within the brain. Conventional treatments display limitations that can be overcome by using nanoparticles for targeted heating. Out of the proposed nanoparticles, this investigation focuses on a new field that utilizes carbon nanotubes (CNTs) which are able to selectively heat the cancer cells since they can convert near infrared light into heat. In the absence of any experiment or theoretical model for the estimation of an effective thermal conductivity of blood and CNTs, a first principle model is developed in this study which takes into account the blood micro-structure. Besides, a number of factors are included, namely the shape and the size of the nanoparticles, the interfacial layer formed around them and their volume fraction.
Firstly, assuming that the blood consists of blood cells and plasma, the thermal conductivity of the former is estimated. Then, the effective thermal conductivity of plasma/CNTs is calculated for various parameters. Finally, the resulting "bio-nanofluid" consisting of plasma/CNTs and blood cells is formed.
It is ascertained that thin and elongated CNTs with relatively large nanolayer thickness as well as large concentrations of CNTs contribute to the increase of the thermal conductivity and, thus, in the enhancement of the heat transfer.
Investigating of how design parameters pertaining to CNTs, such as their size and shape, affect the effective thermal conductivity of blood-CNTs, possible regulating ways are suggested regarding the hyperthermic treatment. Finally, the present simple estimation of the effective thermal conductivity can be used as an effective property of the nanofluid when it comes to numerical investigations regarding heat transfer occurring during hyperthermia or other potential clinical uses (for example targeted heat of living tissues).
本研究涉及热疗，这是一种通过将组织暴露在高温下来破坏癌细胞而对健康组织造成最小损伤的治疗类型。特别是，它专注于多形性胶质母细胞瘤，这是一种最具侵袭性的癌症，始于大脑内部。常规治疗存在局限性，而使用纳米颗粒进行靶向加热可以克服这些局限性。在提出的纳米颗粒中，本研究专注于一个新领域，该领域利用能够选择性加热癌细胞的碳纳米管（CNT），因为它们能够将近红外光转化为热量。由于缺乏用于估计血液和 CNT 的有效热导率的实验或理论模型，本研究中开发了一种第一性原理模型，该模型考虑了血液的微观结构。此外，还包括许多因素，例如纳米颗粒的形状和尺寸、它们周围形成的界面层及其体积分数。
首先，假设血液由血细胞和血浆组成，估算前者的导热系数。然后，计算各种参数下的等离子体/CNT 的有效导热系数。最后，形成由等离子体/CNT 和血细胞组成的“生物纳米流体”。
确定具有相对较大纳米层厚度和较大 CNT 浓度的薄而细长的 CNT 有助于导热系数的增加，从而增强了传热。
研究与 CNT 相关的设计参数（例如其尺寸和形状）如何影响血液-CNT 的有效导热系数，可以提出关于热疗的可能调节方法。最后，目前对有效导热系数的简单估计可作为纳米流体的有效特性，用于涉及热疗期间传热的数值研究或其他潜在的临床用途（例如活组织的靶向加热）。
