Application of synchrotron radiation confocal micro X-ray fluorescence technique in the in-situ study of biology

Abstract

BackgroundSynchrotron radiation confocal micro X-ray fluorescence (confocal μ-SRXRF) micro-probe is a three dimensional analytical method for detecting chemical elements with depth resolution. It can be used to obtain the chemical element information at different depths of samples in situ, which is suitable in the fields of life and environmental sciences.PurposeThis study aims to apply the confocal μ-SRXRF device and in-situ cryogenic device, developed at the hard X-ray micro-focusing beamline (BL15U1) of Shanghai Synchrotron Radiation Facility (SSRF), to analyze the in vivo chemical elemental imaging of biological samples.MethodsConfocal μ-SRXRF was based on K-B mirrors and polycapillary X-ray optics. The foci of the polycapillary X-ray optics and the incident X-ray beam were coincident by continuous scanning and position modification. The confocal μ-SRXRF was used for in-situ XRF imaging analysis of Arabidopsis thaliana seeds and Daphnia magna, and compared with that of conventional μ-SRXRF. The confocal volume was submerged at different depths within the samples to obtain the depth-dependent information. In addition, an in-situ cryogenic device was used to keep Daphnia magna under the cryogenic environment.ResultsThe spatial distributions of chemical elements for in vivo biological samples were directly obtained by confocal μ-SRXRF, without slicing or drying. The specific distribution of chemical elements in plant tissues or organs is more accurately obtained while the absorption and distribution characteristics of chemical elements in organisms are observed more carefully.ConclusionsConfocal μ-SRXRF can be used to directly and effectively analyze the spatial distribution of chemical elements within biological samples. Meanwhile, it can be expanded to analyze the heat-sensitive biological samples and chemical elements by equipping with in-situ cryogenic device, providing a powerful in-situ characterization technique for the life and environment research.

Keywords

• synchrotron radiation
• confocal micro x-ray fluorescence technique
• in-situ cryogenic device