In Situ Quantification Of Living Cell Nucleus Mechanical Propertity With Atomic Force Microscope

The mechanical properties of biological cells are related to the structure, function and the birth and death of the cell closely. The cell is composed of many organelles,in which the nucleus is the main carrier of the genetic materials, and the nucleus plays a vital role in the whole cell life cycle. The study of nuclear mechanical properties can provide insights into nuclear mythical life. While several methods have been developed to characterize nuclear mechanical properties, a AFM(atomic force microscopy) needle penetration technique is demonstrated to mechanically characterize cell nuclei in situ with much higher accuracy and used more widely, and becomes one of the most important methods of exploring the Nano biomechanics field.Here, a self-developed AFM nano-robot system, incorporated a modified AFM needle penetration, is demonstrated to analysis and test the mechanical properties of the cell nuclei in situ, this method can directly measure the viscoelastic properties of nuclei in situ,and can provide a new measure tool and method of studying the mechanical propertity of the nuclei. The main research contents include:First, in this paper, we designed a new modified AFM needle penetration. we considered the issues about how to keep the nuclei in situ, how to measure the stiffness, and the frequency mode and etc. So we can make the AFM needle penetration to have reasonable structure and morphology pattern. This nano robot system can directly measure the mechanical characters of the intact cell nuclei in situ under with minimal damage introduced to the cell.Secondly, in order to gain better experiment data, and improve the visibility of the experiment, we modified the pro-AFM nano robot system, design build and adjust lateral view bottom view observation system, improve the use of left-right operated arm and cell culture substrate for the cell testing. The relationship between the lateral and the longitudinal position of the probe and nucleus can be observed directly during the process of the cell measurement by using the improved system.Then, we used the improved system to measure the nuclei in situ, and the cell was carried on the indentation experiment by using different probes at the same speed, we got the AFM force-displacement data, and gain the cell stress response at the different probes and more reliable results of static mechanical properties of cell by analyzing the data.The new modified AFM probe penetration and the measure methods can measure the mechanical characterizes of the intact cell nuclei in situ with minimal damage introduced to the cell, and change the single view to multi views of simultaneous observation. This can impetus the study for nano biomechanics and provide a new way for the research the cell interior.