The ability of membranes of native human red blood cells (RBCs) to bend into the cell to a depth comparable in size with physiological deformations was evaluated. For this, the methods of atomic force microscopy and atomic force spectroscopy were used. Nonlinear patterns of deep deformation (up to 600 nm) of RBC membranes were studied in normal state and under the action of modifiers: fixator (glutaraldehyde), natural oxidant (hemin), and exogenous intoxicator (zinc ions), in vitro. The experimental dependences of membrane bending for control RBC (normal) were approximated by the Hertz model to a depth up to 600 nm. The glutaraldehyde fixator and modifiers increased the absolute value of Young's modulus of membranes and changed the experimental dependences of probe indentation into the cells. Up to some depth h Hz, the force curves were approximated by the Hertz model, and for deeper indentations h > h Hz, the degree of the polynomial function was changed, the membrane stiffness increased, and the pattern of indentation became another and did not obey the Hertz model. Quantitative characteristics of nonlinear experimental dependences were calculated for deep bending of RBC membranes by approximating them by the degree polynomial function.

中文翻译：

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正常状态和改性剂作用下天然红细胞膜深度变形的非线性生物力学特性

评估了天然人类红细胞 (RBC) 的膜向细胞内弯曲到与生理变形大小相当的深度的能力。为此，使用了原子力显微镜和原子力光谱的方法。在体外研究了在正常状态下和在改性剂的作用下红细胞膜深度变形（高达 600 nm）的非线性模式：固定剂（戊二醛）、天然氧化剂（血红素）和外源性中毒剂（锌离子）。赫兹模型将膜弯曲对控制 RBC（正常）的实验依赖性近似到高达 600 nm 的深度。戊二醛固定剂和改性剂增加了膜的杨氏模量的绝对值，并改变了探针压入细胞的实验依赖性。达到一定深度 h Hz，力曲线采用赫兹模型近似，对于更深的压痕 h > h Hz，多项式函数的次数发生变化，膜刚度增加，压痕模式变为另一种，不服从赫兹模型。通过用次数多项式函数逼近 RBC 膜的深度弯曲，计算非线性实验相关性的定量特征。