Far infrared spectroscopy of biomolecules: a THz-TDS, FTIR and computational study

The long range, large scale molecular motions within biological materials are of great interest in many facets of biochemistry, while there are only limited experimental methods available for characterizing these motions. With the advent of Terahertz time-domain spectroscopy (THz-TDS) and synchrotron based Fourier transform infrared spectroscopy (FTIR), far infrared spectroscopy became one of the emerging techniques that illustrated great potential for this purpose. To fully realize the potential of this part of electromagnetic spectra and overcome the current hurdles in experimentation, this project exploits the parallel advancements in measurement technology, theoretical study and analytical technique to establish an effective research framework. We initially applied the far infrared measurement to a group of model polypeptide molecules using both THz-TDS and synchrotron based FTIR measurement setup, which was followed up by a detailed computational study. With the success in this preliminary study, we further applied the measurement to other biological samples. Such research activities allow us to gain deeper insights, and ultimately find possible applications for these techniques. The major research outcomes for this project were: (1) established a low temperature measurement technique for liquid biological sample; (2) Analysed the whole far infrared spectra and exploited absorption level quantitatively for distinctive spectral features; (3) Revealed the origin of experimental observables through theoretical studies; and (4) Tested the applicability of low temperature measurement technique for other biological systems. These research outcomes collectively enhance the fundamental understanding in far infrared absorption spectra of biological sample and may enable the development of a novel biomolecular fingerprinting technique through structure recognition. From a biochemistry perspective, this research validated a robust measurement scheme and proved the usefulness of far infrared spectra in liquid biological samples. Such technique, when correlated with theoretical studies, may provide unique information for intermolecular and intermolecular dynamics in a system, which opens up great opportunities for developing further biochemistry applications