Studies On The Differences In Electrical Conductivity And Surface Components Of Normal And Cancer Breast Cells By Atomic Force Microscopy

Objective:This paper has studied the differences in electrical conductivity,the distribution of sodium channels on the cell membrane,and the force and binding kinetics of sodium channel-antibody complexes between normal and breast cancer cells.The differences in the electrical characteristics of the cells will lead to a direct understanding of the changes in the physiological and pathological states of the cells,and the differences in the distribution of sodium channels on the cell membrane,the force and binding kinetics between Na _V1.5-antibody complexes will lead to a better comprehension of the role of ion channels in the metastasis and invasion of cancer cells,and will open up new research ideas for the early diagnosis and targeted therapy of breast cancer.Methods:This paper focuses on the differences in electrical conductivity and surface components of normal and breast cancer cells using Conductive Atomic Force Microscopy（CAFM）,Single Molecule Recognition Imaging（SMRI）and Single Molecule Force Spectroscopy（SMFS）.（1）The difference in electrical conductivity between normal and breast cancer cell were investigated at the nanometer spatial level and picoampere current level by CAFM.（2）Voltage-gated sodium channel was detected and localized on the surfaces of normal and cancer breast cells by the SMRI mode of AFM,The specific interaction forces and binding kinetics in the Na _V1.5-antibody complex system were investigated with the SMFS mode of AFM.Results:1.The maximum current distribution of Hs578Bst cell bodies was 1.8632±0.0008p A with a capacitance of 2.38 p F;the maximum current distribution of the processes was 0.4484±0.0003 p A with a capacitance of 2.38 p F.The maximum current distribution of MCF 10A cells was 0.3129±0.0006 p A with a capacitance of 2.78 p F-14.4 p F.The maximum current distribution in the bodies of MD-MAB-231 cells was at 0.1534±0.0009 p A with a capacitance of 1.88 p F;The maximum current distribution of the processes is 78.1226±0.3818 p A and the Schottky barrierφ_βis 0.8391±0.03352.The amplification of the recognition signal on the surface of Hs578Bst cells accounted for（0.6±0.2）%of the cell membrane area（N=5）,while the percentage of the recognition region on the surface of MDA-MB-231 cells was（7.2±1.7）%（N=5）.3.The maximum force distribution of s578Bst cells at a tip loading rate of 0.4n N/s was 52.8±10.3 p N.The binding probability was 19.6%.After blocking with free anti-Na _V1.5 antibody,the binding probability has dramatically decreased to 2.8%.MDA-MB-231 cells showed a maximum force distribution at 35.2±12.5 p N at a tip loading rate of 0.40 n N/s.After blocking,the binding probability has decreased from20.3%to 4.3%.The separation energy barrier from the equilibrium positionх_β=0.20nm and dissociation rate constant at zero force k_off=1.59 s^-1 on Hs578Bst cells,andх_β=0.25 nm and k_off=2.50 s^-1 on MDA-MB-231 cells.Δ（ΔE）for sodium channel-antibody complexes on Hs578Bst and MDA-MB-231 cells was 0.45 k_ВТ.Conclusion:In the conductivity,the bodies of Hs578Bst cells,MCF 10A cells and MDA-MB-231 cells all exhibited typical capacitor behavior with weak conductivity.the cell body capacitance of MDA-MB-231 cells was smaller and slightly more conductive compared to normal breast cells.The processes of normal breast cells also exhibited capacitor behavior,while the processes of breast cancer cells were highly conductive in the micron length range,exhibiting semiconductor-like conductive properties.These suggest that the conductivity of breast cancer cells is superior to that of normal breast cells.In terms of components,the sodium ion channel Na _V1.5 is not distributed uniformly on the cell surface,with approximately 12 times more Na _V1.5 on cancer cells than on normal cells.Thus quantitative information on Na _V1.5 in normal and breast cancer cells is given for the first time by SMRI.Na _V1.5-antibodies are more stable on normal breast cells than on cancer cells.In summary,this paper investigated the differences in electrical conductivity and surface Na _V1.5 distribution between normal and breast cancer cells by AFM.This work has advanced the study of the differences between normal and breast cancer cells to the level of nanospatial resolution,picoamperial current resolution,pico-capacitance resolution and pico-mechanical resolution which will help to further investigate the electrical conductivity of normal and cancer cells at the nanoscale level,and will also help to further investigate study the interactions of other ion channel-antibody systems,and will also be useful to understand the role of sodium channels in tumor metastasis and invasion.