Study On Measurement And Imaging Of Photon Polarization Status In Nano-Scattering Field And Its Biological Application

Cells,viruses and biomacromolecules have an important influence on life activities.The detection and morphology characterization of these biological samples are the basis of life research.Optical microscopic imaging has great advantages in the characterization and detection of biological samples because of its characteristics of low sample requirements,good environmental adaptability,convenient,fast and non-destructive detection.However,due to the influence of optical diffraction limit,the resolution of optical microscopic imaging method is comparative low and thus limits the applications.Due to the polarization characteristics of the scattering field from scatterer are closely related to the microstructure of the scatterer,the measurement of the polarization characteristics of the scattering field can improve the detection and characterization ability of biological samples.In this paper,based on the measurement and imaging method of photon polarization status in nano-scattering field and numerical simulation of Finite-Difference Time-Domain(FDTD)method,the Au Nanoparticles(Au NPs)and nanopores were used to measure the polarization parameters of scattering field.High sensitive imaging detections of adenovirus and Shp2 protein molecules have been achieved.The multiscale cells with ellipsoidal,long-rod and irregular shapes were imaged with high resolution in the absence of fluorescent labeling.The main contents and results are as follows:According to the Mie scattering theory,the quasi-static approximation,the geometrical optics approximation and the Rayleigh-Debye-Gans approximation,the scattering field expressions of electric dipole,spherical and ellipsoidal particles were summarized and given.Based on the polarization phase delay introduced by scatterers,a method for measuring photon polarization status in scattering field named as Polarization parametric Indirect Microscopic Imaging(PIMI)was proposed.The polarization parameters were calculated through Mueller matrix derivation and Fourier series expansion.The PIMI system was built with Liquid Crystal Variable Retarder(LCVR).The phase retardance of LCVR and the relationship between polarization rotation angle and phase retardance were accurately calibrated.Based on Fresnel’s reflection law,the linear polarization aberrations introduced by the unpolarized beam spliter and the high numerical aperture objective in the system were quantified and calibrated,and the corresponding angle compensation was made for the linear polarization aberration.For the detection of protein molecules,a method of PIMI combining nanopore structures was proposed.Based on the electric dipole approximation and FDTD simulation method,the scattering characteristics of solid-state nanopore and solid-state nanopore modified with Shp2 protein molecules were analyzed.The Shp2 protein molecule detection was realized by distinguishing the difference of distribution of scattering field before and after solid-state nanopore modification.In order to further realize the high-throughput and quantitative detection of Shp2 proteins,a new kind of nano-cylindrical hole array structure was put forward and designed.The nano-cylindrical hole array was then characterized by PIMI method.By using Fourier Ring Correlation(FRC)method,the resolution of PIMI results was calculated as 88 nm.In addition,the effects of the internal structure of the nanocylindrical hole on the scattering distribution were studied by FDTD simulation.And it was also verified by FDTD that a volume difference of 0.01409 fl of Shp2 proteins in the nanocylindrical hole can be detected by PIMI method.Finally,the experimental PIMI results were futher improved by Generative Adversarial Network(GAN).To realize the detection of virus particles under diffraction limit,a method of PIMI combining Au NPs was proposed.Based on the quasi-static approximation method and FDTD simulation,the characteristics of local scattering field of Au NPs were analyzed.By using PIMI method,the characterization of the local scattering field distribution of Au NPs was obtained.FDTD simulations were also verified the above experimental result.By using Au NPs as optical probes to label the adenovirus,Au NP-Virus were then obtained.Based on the difference of scattering distribution of single Au NP and Au NP-Virus,the 80-nm adenovirus was thus distinguished and detected by PIMI method.For further improvement of the above PIMI results,the Neural-Encoded(NE)neural network was used to denoise.The difference of scattering distribution of single Au NP and Au NP-Virus was enhanced after denosing and the accuracy of adenovirus detection was thus improved.Morever,the variation of the scattering distribution corresponding to single Au NP and Au NP-Virus with different sizes was studied by FDTD simulation.The photon polarization status of scattering field of multiscale cells with ellipsoidal,long-rod and irregular shapes were measured.The scattering characteristics of different cells were analyzed first based on different cell models and FDTD simulation.In the absence of fluorescent labeling,the high-resolution images of the microstructures of cervical cells and bacterial cells were obtained through PIMI method,including the morphology of cells,the organelles such as nucleus and mitochondria,the surface folds on bacteria,boundaries positions and so on.It was found that the resolution of PIMI imaging method is higher than that of traditional optical microscopy and Differential Interference Contrast(DIC)microscopy.PIMI method can thus be used as a new observation method for pap smear detection and microbial culture research based on its super-resolution ability in cell microstructures analysis.