| Brain science is a frontier scientific research worldwide.Studies on brain structures and brain diseases are important contents of brain science.Conventional imaging techniques such as computed tomography,magnetic resonance imaging,fluorescence molecular imaging and positron emission tomography are largely dependent on externally introduced materials(e.g.,contrast agents,fluorophores and radioactive chemicals),which hindered us to a certain degree,to in-depth recognition of brain structures and diseases.Thence,new techniques are urgently needed to precisely detect brain structures and brain diseases,which should be,ideally,independent on any externally introduced materials.Synchrotron radiation-based Fourier transform infrared(SR-FTIR)and terahertz time-domain spectroscopic imaging techniques are newly developed label-free spectral imaging approaches that can be used to precisely detect chemical,physical and structural properties of biological samples,and the two techniques are well complementary to each other in revealing material properties.The above methods can be utilized to accurately obtain the intrinsic compositional and structural properties of biological samples without bringing in any externally materials.Unfortunately,although SR-FTIR and/or THz imaging techniques can provide an ideal platform to probe the brain structure and brain diseases,hitherto only relatively little attention has been received by the scientific community,and have not been properly applied to brain science research.For the above reasons,in this project,we employed SR-FTIR and THz spectroscopic imaging techniques to investigate the slices of normal and diseased mouse brain tissues(traumatic injured brain tissue and brain glioma tissue,to reveal their structural and chemical information.This research has been carried out by implementing the following work:(1)Normal,traumatic brain injury(TBI)and glioma mouse models were established,respectively;and brain tissue slice samples were obtained.(2)The slice samples were examined by conventional histopathological techniques including hematoxylin and eosin staining,and 2,3,5-triphenyltetrazolium chloride staining,from which the normal region could be differentiated from the injured region or from the glioma by different stained colors.Afterwards,the slices were imaged by SR-FTIR microspectroscopy.By analyzing the SR-FTIR data using image reconstruction and principal component analysis classification,it was found that the contents of lipid,protein and/or nucleic acid was different in the normal and injured regions,as well as in the normal and glioma regions.The results show that lipid,protein and nucleic acid can be used as biomarkers to unambiguously distinguish the normal and injured regions or normal and glioma regions.(3)The samples were also imaged by terahertz(THz)time-domain spectroscopy.The results show that the normal and injured regions,or the normal and glioma regions can be successfully distinguished with the frequency amplitude imaging technique,and the calculated THz refractive index and absorption coefficient are different in different regions.Through systematic study carried out in this project,it was proved that the SRFTIR and/or THz spectral imaging technique could be used to detect brain structures and identify brain diseases.The two techniques can reveal the structural,chemical and physical properties of the examined brain tissue samples from different aspects.The results of our work provided useful information on in-depth understanding of brain structures and diseases,and laid a preliminary foundation for the practical application of SR-FTIR and/or THz techniques in biological detection. |
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