Microrheology of human lung epithelial cells measured by atomic force microscopy
Microrheology of human lung epithelial cells measured by atomic force microscopy
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DOI：
10.1016/s0006-3495(03)75014-0
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发表时间：
2003-03-01
影响因子：
3.4
通讯作者：
Navajas, D
中科院分区：
文献类型：
--
作者：
Alcaraz, J;Buscemi, L;Navajas, D
肺上皮细胞受到来自呼吸的大的循环力。然而，它们对动态应力的反应定义不清。我们用原子力显微镜测量了人肺泡（A549）和支气管（BEAS-2B）上皮细胞在三个频率十年（0.1-100 Hz）和不同加载力（0.1-0.9 nN）下的复合剪切模量（G*（Ω））。G*（Ω）的计算通过修正力压痕振荡数据的尖端细胞接触几何形状和流体动力学粘性阻力。两种细胞类型显示出相似的粘弹性。储能模量G ′（ω）随频率的增加符合幂律，指数近似为0.2。损耗模量G”（ω）比G '（ω）低2/3，并且与G'（ω）类似地增加，直到接近10 Hz，但是在较高频率下表现出更陡的上升。细胞显示出对G '（ω）和G”（ω）的弱力依赖性。G*（Ω）符合幂律模型，结构阻尼系数接近0.3，表明细胞内弹性和耗散过程的耦合。幂律行为意味着应力松弛时间常数的连续分布。这种复杂的动力学与接近玻璃化转变的软玻璃质材料的流变学是一致的，从而表明结构紊乱和亚稳性可能是细胞结构的基本特征。
Lung epithelial cells are subjected to large cyclic forces from breathing. However, their response to dynamic stresses is poorly defined. We measured the complex shear modulus (G*(omega)) of human alveolar (A549) and bronchial (BEAS-2B) epithelial cells over three frequency decades (0.1-100 Hz) and at different loading forces (0.1-0.9 nN) with atomic force microscopy. G*(omega) was computed by correcting force-indentation oscillatory data for the tip-cell contact geometry and for the hydrodynamic viscous drag. Both cell types displayed similar viscoelastic properties. The storage modulus G'(omega) increased with frequency following a power law with exponent similar to0.2. The loss modulus G"(omega) was similar to2/3 lower and increased similarly to G'(omega) up to similar to10 Hz, but exhibited a steeper rise at higher frequencies. The cells showed a weak force dependence of G'(omega) and G"(omega). G*(omega) conformed to the power-law model with a structural damping coefficient of similar to0.3, indicating a coupling of elastic and dissipative processes within the cell. Power-law behavior implies a continuum distribution of stress relaxation time constants. This complex dynamics is consistent with the rheology of soft glassy materials close to a glass transition, thereby suggesting that structural disorder and metastability may be fundamental features of cell architecture.