Bremmell Kristen E, Evans Allan, Prestidge Clive A
Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
Colloids Surf B Biointerfaces. 2006 Jun 1;50(1):43-8. doi: 10.1016/j.colsurfb.2006.03.002. Epub 2006 May 15.
Interaction forces, deformation and nano-rheology of individual red blood cells in physiologically relevant solution conditions have been determined by colloid probe atomic force microscopy (AFM). On approach of the physically immobilised cell and silica glass spherical probe surfaces, deformation of the red blood cell was observed in the force curves. At low levels of deformation, spring constants were determined in the range 3-6 m Nm(-1), whereas for higher levels of deformation, the forces increase non-linearly and on retraction, significant force curve hysteresis is observed (i.e. lower forces upon retraction). The extent of force curve hysteresis was dependent on both the drive velocity and loading force, typical of a viscoelastic system. The response of the red blood cell has been described by viscoelastic theory, where the short and long time scale elastic moduli and relaxation times are determined, i.e. the cell's nano-rheological properties elucidated. In addition to a time independent elastic modulus of 4.0 x 10(3)Nm(-2) at low levels of deformation, time-dependent elastic moduli ranges are observed (3.5 x 10(4) to 5.5 x 10(4)Nm(-2) at intermediate levels of deformation and 1.5 x 10(5) to 3.0 x 10(5)Nm(-2) at higher levels of deformation). That is, one elastic and more than one viscoelastic response to the red blood cell deformation is evident, which is considered to reflect the cellular structure.
通过胶体探针原子力显微镜（AFM）测定了生理相关溶液条件下单个红细胞的相互作用力、变形和纳米流变学。在物理固定的细胞与二氧化硅玻璃球形探针表面靠近时，在力曲线中观察到红细胞的变形。在低变形水平下，测得的弹簧常数范围为3 - 6 mN/m，而在较高变形水平下，力呈非线性增加，并且在回缩时观察到明显的力曲线滞后现象（即回缩时力较低）。力曲线滞后的程度取决于驱动速度和加载力，这是粘弹性系统的典型特征。红细胞的响应已用粘弹性理论进行描述，其中确定了短时间和长时间尺度的弹性模量以及弛豫时间，即阐明了细胞的纳米流变学特性。除了在低变形水平下有一个与时间无关的4.0×10³ N/m²的弹性模量外，还观察到了与时间相关的弹性模量范围（在中等变形水平下为3.5×10⁴至5.5×10⁴ N/m²，在较高变形水平下为1.5×10⁵至3.0×10⁵ N/m²）。也就是说，对红细胞变形存在一种弹性响应和一种以上的粘弹性响应，这被认为反映了细胞结构。
