Kilbride Peter, Rull Marina Vazquez, Townsend Adam, Wilson Helen, Morris John
Asymptote Ltd., General Electric Healthcare, Cambridge, UK.
Department of Mathematics, University College London, London, UK.
Biorheology. 2019;56(1):39-50. doi: 10.3233/BIR-180196.
The rheology of shear thickening fluids is well characterized for many physical applications, however the literature surrounding biologically or cryobiologically compatible shear thickening fluids is less well understood.
This study examined fluids consisting of corn-derived hydroxyethyl starch with a variety of sugars and cryoprotectants to characterize their shear-rate viscosity relationship. The objective was to establish if cryobiologically relevant materials could be used to afford biologics protection through shear-thickening.
Fluids consisting of 50% hydroxyethyl starch by weight exhibited shear thickening with a variety of cryoprotectants. Lowering the temperature of the fluid both reduced critical shear rates and enhanced thickening magnitude. Starch derived from corn, wheat, and rice all exhibited non-Newtonian shear-dependent viscosity behaviour at 50% by weight in water. Between the starch sources however, the shear-rate viscosity relationship varied widely, with wheat-derived starch shear thinning, and the remaining starches forming shear thickening fluids. Different starch sources had different baseline viscosities, critical shear rates, and rates of viscosity increase.
This study established that shear thickening is compatible with cryobiologically relevant agents, particularly so at lower temperatures. This forms the basis for harnessing these phenomena in biological processes such as cryopreservation.
剪切增稠流体的流变学在许多物理应用中已有充分表征，然而，关于生物或低温生物学兼容的剪切增稠流体的文献却了解较少。
本研究考察了由玉米衍生的羟乙基淀粉与多种糖类和冷冻保护剂组成的流体，以表征其剪切速率与粘度的关系。目的是确定与低温生物学相关的材料是否可用于通过剪切增稠为生物制品提供保护。
由重量比为50%的羟乙基淀粉组成的流体与多种冷冻保护剂表现出剪切增稠现象。降低流体温度既降低了临界剪切速率，又增强了增稠幅度。玉米、小麦和大米衍生的淀粉在水中重量比为50%时均表现出非牛顿剪切依赖型粘度行为。然而，在不同淀粉来源之间，剪切速率与粘度的关系差异很大，小麦衍生的淀粉表现出剪切变稀，其余淀粉形成剪切增稠流体。不同淀粉来源具有不同的基线粘度、临界剪切速率和粘度增加速率。
本研究证实剪切增稠与低温生物学相关试剂兼容，尤其是在较低温度下。这为在诸如冷冻保存等生物过程中利用这些现象奠定了基础。
