Rheology of biocompatible ferrofluids in blood

在过去的几十年里，磁性颗粒悬浮液在生物医学应用中的应用--特别是在癌症治疗中的应用--吸引了越来越多的兴趣。在此背景下，基础研究表明，特别是通常被称为磁性药物靶向的方法的流体力学方面，即向肿瘤区域的磁控递送，仍然需要澄清许多基本方面。在这方面特别令人感兴趣的是各个悬浮液在磁场存在下的粘性行为的变化，这是澄清基本流体力学问题所需的。初步实验表明，即使在弱磁场中，生物相容磁流体的粘度也会显着增加，同时其流动行为也会发生变化。这是因为这样一个事实，即在这种生物兼容的磁流体中存在相对较大的磁性颗粒簇，表现出强烈的磁矩，这导致了强烈的颗粒间相互作用。此外，初步调查表明，即使用水或血液稀释液体，观察到的影响仍然存在。因此，澄清血液中磁性粒子悬浮液的流变性，即医疗应用中存在的这些混合物的流动行为，是该项目的中心目标。在毛细管流变学的流变学实验中，可以预见在很宽的场强、剪切速率和流体组成范围内研究流体的流变行为。这些研究的最终目标将是为这种悬浮液在磁场中的流动行为建立一个本构的材料定律，这将使生物医学应用的模拟成为可能。

The use of suspensions of magnetic particles in biomedical applications - especially in cancer therapy has attracted growing interest in the past decades. In this context basic investigations have shown, that especially the fluid mechanics aspects of an approach commonly called magnetic drug targeting, i.e. a magnetically controlled delivery towards a tumor zone, still require the clarification of numerous fundamental aspects. Of particular interest in this respect are changes of the viscous behavior of the respective suspensions in the presence of magnetic fields that are needed for the clarification of basic fluid mechanical questions. Preliminary experiments have shown that biocompatible ferrofluids show a significant increase in their viscosity accompanied by the appearance of changes in their flow behavior even in weak magnetic fields. This is forced by the fact that comparably large clusters of magnetic particles exist in such biocompatible ferrofluids exhibiting a strong magnetic moment, which gives rise to strong interparticle interaction. The preliminary investigations have moreover shown that the observed effects subsist even if the fluids are diluted with water or blood. Thus, it is the central objective of project to clarify the rheology of suspensions of magnetic particles in blood, i.e. the flow behavior of those mixtures present in medical applications in detail. It is foreseen to investigate the rheological behavior over a wide range of field strength, shear rate and fluid composition in rheological experiments using capillary rheology. The final goal of these investigations will be the establishment of a constitutive material law for the flow behavior of such suspensions in a magnetic field, which will allow simulations of biomedical applications.