Fast P-THG microscopy for the characterization of biomaterials

摘要

The application range of P-THG microscopy has been so far restricted to studies on molecular order and anisotropy ofstatic specimen removed from their biological environment. Slow polarization commutation limits the investigation ofhighly dynamic systems because of motion artifacts. Here we have developed a new fast-P-THG microscope enablingefficient in vivo studies in dynamic biological samples. Our P-THG scheme benefits from a built-in EOM that switchpolarization states at kilohertz between image lines to provide artefact-free P-THG images with micrometric resolution.Furthermore, we have developed a fast Fourier analysis enabling rapid P-THG processing to quantify lipid order andangular maps. We demonstrated that fast-P-THG is suitable in two major applications. Using first a linear polarizationconfiguration, fast P-THG imaging revealed molecular order changes in MLVs undergoing phase-transition upon heatingdespite sample distortions. Anisotropy properties of small endogenous microparticles swimming in the otolith cavityembryos were also reported in early zebrafish embryos. A second configuration with linear-circular polarizationcommutation enabled efficient detection of birefringent media such as anisotropic vesicles in C-elegans gut cells.