Interfacial Water Mediated Biological Macromolecule Interaction Characterizing By Terahertz Spectroscopy

As an important prerequisite for life,biomolecules under physiological conditions are surrounded by interface water in the spatial confinement of aqueous microenvironment,and perform their functions.The biological macromolecules and interface water involved in the biochemical process have collective dynamics characteristics in the terahertz frequency range.In principle,terahertz spectroscopy can provide dynamics on picosecond time scale of the interface water and biological process mediated by it.However,the biological characterization by terahertz spectroscopy is limited to some extent: terahertz spectroscopy mainly focuses on the detection of single biomolecules,and there is still a large distance from the biological detection of real environment of biological processes;under the existing technical conditions,the strong terahertz absorption of water molecules all over the living system hinders the terahertz detections of complex biological system in detail.In order to expand the application scope of terahertz detection of biomolecules,revealing the dynamical characteristics of complex biological system in terahertz range,this thesis has developed a terahertz spectroscopic characterization method for the interaction of biological macromolecules mediated by interface water.The research consists of the following three parts:In the first part,based on the self-assembly properties of amphiphilic phospholipid molecules,a phospholipid reverse micellar droplet system is constructed in a continuous phase with high terahertz transmittance and applied to biological terahertz detections.This droplet system takes the advantages of spatial confinement water dispersed phase to solve the huge obstacle to the absorption of a large number of water molecules in terahertz detections,and at the same time provides a celllike aqueous microenvironment for biological characterization.Subsequently,the droplet system has been applied to interfacial ion-lipid interaction confined in phospholipid reverse micelles,and discovering a specific binding of copper ion to phosphatidylglycerol phospholipid headgroup.These findings proved that the metal ion effects on water dynamics confined in phospholipid reverse micelles can be detected by using terahertz spectroscopy,thus providing a new view and sensitive tool for the investigation of the interaction between trace metal ions and the biological membrane.the detection of the influence of copper ions on the hydrodynamics of the cell membrane interface.The detection revealed the specific interaction of copper ion-phosphatidylglycerol phospholipid membrane,and it was found that copper ions destroyed the hydrogen bond network structure of the phosphatidylglycerol phospholipid membrane hydration layer,and restored the rotational rearrangement kinetics of part of the interfacial water.In the second part,the droplet terahertz strategy is applied to probe the low frequency collective hydration dynamics of multidomain proteins and phospholipid-protein interactions,and the terahertz spectra of protein molecules in the interfacial aqueous solution are analyzed.The terahertz spectra have revealed the internal conformational changes of coagulation factor proteins induced by calcium ions and the interaction between the phosphatidylserine phospholipid and the coagulation factor ?.Based on the terahertz results,the low-frequency collective vibration modes of protein in the terahertz frequency band have been calculated and elucidated depending on the interface property of aqueous microenvironment.Furthermore,the terahertz signal variations of lactadherin induced by calcium ions and hydrogen are compared to the coagulation factor ?,implying the relationship between the biomolecule terahertz characteristics and their biological functions.In the third part,the droplet system is innovatively integrated with terahertz metamaterial.Taking advantages of terahertz metamaterial to enhance the localized electric field of terahertz waves and the light-matter interaction with adjacent analytes,the biomolecule detection sensitivity is further improved.Based on this biomolecule detection strategy,the combination of the water nanodroplet with metamaterial surface allows terahertz spectroscopy to sensitively determine trace amyloid ? aggregates in aqueous liquids,offering a valuable toolkit towards bioanalytical applications in AD and other brain-related diseases.In summary,interface water has been employed as medium for the terahertz spectroscopy of biological macromolecules to develop and improve the terahertz characterization of biological macromolecule interactions based on the water droplet system.Focused on specific biological interests,the phenomenon of biomolecules at terahertz frequency scale is elucidated.These results help reveal the dynamical characteristics of the interaction of biomolecules in aqueous environment at the low-frequency collective field,and increase the understanding of terahertz biology.