Research On Cell Behavior Based On The Nanomechanical Fluctuations

Mechanical phenomena widely exists in living organisms.The study of various mechanical effects in cell growth and development can help human beings better understand how living organisms work,which is important for the prevention and treatment of various diseases.So far,there have been lots of studies on the mechanical characteristics of cells such as traction force,morphological changes,and modulus changes,which are often slow,ranging from a few minutes to several days.In fact,there are many intracellular activities of much shorter time scale,such as the assembly and depolymerization of microfilaments and microtubules,and the transport of intracellular materials between organelles.These activities cause nanomechanical vibrations o rather than changes in force,morphology,or modulus in the cell.Here,we studied nanomechanical vibrations of cells.The main results of this paper are as follows:We built a sensing platform that can detect nanomechanical vibrations of cells and biological samples,the parts of which were introduced in detail.The principle and implementation of the displacement platform were described.The heat transfer model of the temperature control platform was constructed,and the simulation calculations were carried out.We also optimized the vibration isolation of the system.The whole suspension vibration isolation design was analyzed theoretically and the vibration isolation curve was calculated.The results show that the vibration isolation structure we built was able to greatly reduce the influence of external disturbances.We investigated the cellular metabolic activity of oocytes in different stages during meiosis by nanomechanical vibrations.We found that oocytes at germinal vesicle(GV)stage induced significant nanomechanical vibrations,and those with low activity induced less nanomechanical vibrations.The same results were obtained by inhibiting cell metabolism through drugs.We also found that the nanomechanical vibrations induced by oocytes at different stages were different,and the nanomechanical vibrations induced by oocytes at GV stage were significantly more intense than those induced by oocytes at other stages.The staining results of oocytes at different stages showed that the mitochondria and cytoskeleton of GV stage oocytes were significantly different from those of the metaphase stage of the first meiosis(MI)and the metaphase stage of the second meiosis(MII).It was observed that there were a denser distribution of mitochondria and microfilaments under the cell membrane of GV stage oocytes.There were also a large number of microfilament structures inside zona pellucida of oocytes in GV stage,which was not observed in other stages.We suggest that the spatial distribution of the oocyte skeletal structure and metabolic capacity ultimately led to the differences of the nanomechanical vibrations we detected.We proposed a nanomechanical sensing approach to study the early cleavage of human fertilized eggs.We found that both oocytes of failed fertilization and fertilized eggs in the cleavage process can induce significant nanomechanical vibrations.Then we analyzed the differences between oocytes of failed fertilization and fertilized eggs in the cleavage process,and found that the nanomechanical vibrations of fertilized eggs in the cleavage process were significantly stronger than those of oocytes of failed fertilization.This suggest that the nanomechanical vibrations during cleavage have certain characteristic frequency patterns,which we considered may be related to changes in cell structure and metabolism.Epithelial-mesenchymal transition(EMT)is an important step for the initiation of tumor metastasis.We proposed a method to study the process of epithelial mesenchymal transition(EMT)of the cell colony based on nanomechanical vibrations.The nanomechanical vibrations induced by cell colony of different phenotypes were recorded by microcantilever.Contrast experiments showed that cell colony induced significant nanomechanical vibrations,which indicated that microcantilever beam vibrations could detect the nanoactivities of cell colony.It was found that nanomechanical vibrations induced by the cell colony became larger with the occurrence of EMT,and the spectrum of nanomechanical vibrations produced a series of frequency shifts.Furthermore,we investigated the effect of cytoskeletal structure and adhesion of cell colony on nanomechanical vibrations and performed correlational analysis and causal inference of the enhanced nanomechanical vibrations during the EMT process of cell colony.In general,the aim of this paper is to study the behavior of cells through their nanomechanical vibrations.The meiotic process and the oogenesis process after fertilization of germ cells were investigated and the invasion(epithelial mesenchymal transition)process of cell colony was also explored.This is not only a further exploration of the content and research tools of cell mechanics,but also contributes to a deeper understanding of the way cells exist and operate.