Application Of Nonlinear Optical Imaging In Biology And Materials

Nonlinear optical imaging can realize the non-marking and non-contact imaging of samples,and has the characteristics of high spatial resolution,tomographic imaging and large penetration depth.With its excellent characteristics,it has broad application prospects in the fields of biomedicine,life sciences,and materials science.This paper mainly applies it to the imaging research of snail bone tissue,porous carbon materials and white lily pollen grains to observe the biological evolution relationship between collagen and mineral components during the process of bone tissue formation by nonlinear microscopic imaging of snails,to reveal its ability to characterize the structure of porous carbon materials and to study its role in visualization research of pollen grains.In this paper,coherent anti-Stokes Raman scattering?CARS?,second harmonic generation?SHG?,and two-photon excited fluorescence?TPEF?imaging of snail have been performed.The spatial distribution relationship between ions(Carbonate ion(CO₃^2-)and phosphate ion(PO₄^3-)related to the mineral component and collagen has been observed.During the occurrence of snail bone tissue,it is observed that the ions related to the mineral components are first dispersed in the liquid environment,and collagen are observed two days later,and then the ions gradually approached the collagen,and finally formed minerals.As bone tissue matures,collagen gradually fades.The experimental results show that CARS and SHG can well reveal the biological evolution relationship between collagen and mineral components in snail bone tissue,and can clearly observe the biological evolution of snail structure and morphology day by day.The CARS,SHG and TPEF imaging have been performed on porous carbon materials.The 2D CARS imaging pictures have been obtained through Z-scan technology.The 3D CARS imaging pictures have been gained by reconstructing the 2D CARS pictures,and the3D rotating CARS imaging pictures have been also acquired.The 2D and 3D CARS images with rotations can clearly characterize the structures and properties of porous carbon materials,including the surface and inner parts.SHG proves the inversion symmetry breaking of porous carbon materials,which is not centrosymmetric materials.TPEF imaging picture shows autofluorescence signal of porous carbon material,which provides direct evidence for the transfer of photon momentum to the electronic system.Experimental results demonstrate that the nonlinear optical microscopy is a great optical analysis method for the study of porous carbon materials,and it can be potentially used for the optical characterization on the materials at micro-nano scale.The CARS and TPEF images of the white lily pollen grains including 2D and 3D images have been obtained.The distribution patterns and spatial position relationships of lipid,fluorescent substance and carotenoid in the lily pollen have been observed.2D imaging pictures at different depths show that the lipid is located inside and partially intersects with the fluorescent substance and carotenoid and the carotenoid is contained in the fluorescent substance on the side of the pollen wall surface layer.The 3D and its rotation images can observe the network morphology of the surface and internal texture of the pollen wall.The experimental results show that the nonlinear microscope can be used to visualize pollen.In conclusion,our research shows that nonlinear optical imaging provides detailed information on the relationship between mineral composition and collagen in bone tissue,characterizes the structure and performance of porous carbon materials,and visualize the morphological structure of pollen.With the development of technology,nonlinear optical imaging may become an important method in bone repair research.