Mechanical fluidity of fully suspended biological cells.
Mechanical fluidity of fully suspended biological cells.
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完全悬浮的生物细胞的机械流动性。
DOI：
10.1016/j.bpj.2013.08.040
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发表时间：
2013
影响因子：
3.4
通讯作者：
VanVliet,KrystynJ
中科院分区：
文献类型：
--
作者：
Maloney,JohnM;Lehnhardt,Eric;Long,AlexandraF;VanVliet,KrystynJ
单个生物细胞的机械特性被用来识别和可能利用细胞或细胞群体之间有趣的差异。流动性--归一化到弹性固体或粘性液体的极值的滞后性--可以从细胞的多种流变学测量中提取并在其中进行比较：蠕变柔量与时间、复数模数与频率以及相位滞后与频率。由于有多种策略可用于获取这种无量纲特性，流动性可以作为区分细胞群体和理解软物质中变形能力的物理起源的有用和稳健的参数。在这里，对于三种不同的真核细胞类型，通过光学拉伸，我们在∼1 S的时间尺度上考察了流动性对化学和环境影响的依赖性。我们发现，在结构阻尼(幂定律或分数导数)模型下，流动性估计在时间域和频域中是一致的，但在等价复杂性的集总分量(弹簧-Dashpot)模型下则不一致；后者预测的是虚假的时间常数。尽管化学交联抑制了流动性，但我们发现细胞中的ATP耗尽并不能显著改变参数，因此我们得出结论，在悬浮细胞的线性粘弹性变形过程中，活跃的ATP驱动事件不是流动性的关键使能因素。最后，通过使用光学拉伸的能力来产生细胞温度的近乎瞬时的上升，我们建立了流动性随温度的增加-现在在完全悬浮的、可分选的细胞中测量，没有细胞-基质粘附性的复杂因素。
Mechanical characteristics of single biological cells are used to identify and possibly leverage interesting differences among cells or cell populations. Fluidity—hysteresivity normalized to the extremes of an elastic solid or a viscous liquid—can be extracted from, and compared among, multiple rheological measurements of cells: creep compliance versus time, complex modulus versus frequency, and phase lag versus frequency. With multiple strategies available for acquisition of this nondimensional property, fluidity may serve as a useful and robust parameter for distinguishing cell populations, and for understanding the physical origins of deformability in soft matter. Here, for three disparate eukaryotic cell types deformed in the suspended state via optical stretching, we examine the dependence of fluidity on chemical and environmental influences at a timescale of ∼1 s. We find that fluidity estimates are consistent in the time and frequency domains under a structural damping (power-law or fractional-derivative) model, but not under an equivalent-complexity, lumped-component (spring-dashpot) model; the latter predicts spurious time constants. Although fluidity is suppressed by chemical cross-linking, we find that ATP depletion in the cell does not measurably alter the parameter, and we thus conclude that active ATP-driven events are not a crucial enabler of fluidity during linear viscoelastic deformation of a suspended cell. Finally, by using the capacity of optical stretching to produce near-instantaneous increases in cell temperature, we establish that fluidity increases with temperature—now measured in a fully suspended, sortable cell without the complicating factor of cell-substratum adhesion.