Analysis Of The Dielectric Spectral Characteristics Of Human Lung Squamous Carcinoma Cell Suspensions

Objective: As a mature spectroscopy technique with elaborate measurement and complete analytical methods,the dielectric spectrum has broadened its application scope from physics to biology and medicine immensely.This thesis focused on investigating the dielectric response to the biological changes of human lung cancer cell in suspension,and the feasibility of utilizing the technique of dielectric spectrum for human lung cancer screening and cancer cell identification.Method: Firstly,the dielectric spectra in the frequency range from 100 Hz to 100 MHz of two human lung cell lines,the normal human bronchial epithelial cell BEAS-2B,and the human lung squamous carcinoma cell SK-MES-1,were measured in suspensions of different volume fractions utilizing an Agilent 4294 A impedance analyzer and a two-electrode measuring chamber.Then,a three-term Cole-Cole analytical model and a single spherical shell model were adopted to further analyze the measured dielectric spectra of SK-MES-1 and BEAS-2B suspensions.The Cole-Cole model parameters,such as the relaxation intensities,the characteristic frequencies,and the low-frequency limit of conductivity can be obtained by the nonlinear least square curve fitting technique.Finally,the feasibility and implementation detail of human lung cancer cell identification under laboratory conditions based on the discrepancy illustrated in the dielectric spectra and model parameters were analyzed.This thesis also discussed the pathology study of human lung cancer from the perspective of biophysics,and established the relationship between the differences in dielectric spectrum and the morphological change of cells.Results: 1.The dielectric spectra of the cancerous SK-MES-1 cell and the normal BEAS-2B cell suspensions were significantly different.The permittivity of the cancerous SK-MES-1 cell was smaller than the normal BEAS-2B(5.81%),while the conductivity of SK-MES-1 was higher(12.25%).2.The volume fractions of cell suspensions influenced the shape of dielectric spectra.3.Both Alpha and Beta dielectric relaxation can be observed in the dielectric spectra of cell suspensions measured in the frequency range from 100 Hz to 100 MHz.4.A three-term Cole-Cole model had to be adopted to fit the measured dielectric spectra accurately for both the cancerous SK-MES-1 and BEAS-2B cell suspensions.This result illustrated that all of the dielectric spectra of the suspensions were synthetized by three dielectric relaxations of different characteristic frequencies and relaxation intensities.The three dielectric relaxations were induced by interfacial polarization and ionic polarization separately which occur in different frequency ranges.5.The characteristic frequencies differentiated significantly between SK-MES-1 and BEAS-2B,and were not influenced by the volume fractions of cell suspensions according to the statistical analysis using the one variable linear regression model.This finding illustrated that it was feasible to distinguish the cancerous SK-MES cell from the normal BEAS-2B cell based on both the graphic dielectric spectra and the numerical Cole-Cole model parameters which was more intuitively.6.The single spherical shell model can be adopted to analyze the measured dielectric spectra.The model parameters can be utilized not only to distinguish the cancerous and normal cells,but also to explain the morphological differences observed in the stereoscan photographs of the cancerous SK-MES-1 and the normal BEAS-2B cells.Conclusion: In summary,the feasibility,implementation details,and significance of employing the comprehensive dielectric spectrum measurement and analytical technique to distinguish the human lung cancer cell from the normal cell in suspensions were investigated and revealed in this thesis.