Terahertz TimeDomain Spectroscopy of Glucose and Uric Acid

Terahertz Time-Domain Spectroscopy of Glucose and Uric Acid Prashanth Upadhya, Yao-Chun Shen, Giles Davies & Edmund Linfield Cavendish Laboratory, Cambridge University

Contents Introduction Experiment Far-infrared absorption Glucose and sucrose Uric Acid & its derivative Temperature & structural dependent absorption Conclusions

Introduction many intrinsic resonances predicted in the THz regime vibrational modes in polynucleotides …Powell et al base twisting and librational modes in DNA structure … Young et al low frequency collective vibrational modes distinguish between different isomeric configurations in retinal molecules … Walther et al finger print of conformational state – benzoic acid …Walther et al

Vacuum capable THz-TDS set-up useful bandwidth of 0. 1 - 3. 0 THz spectral resolution of better than 1 cm-1

Sample preparation pellets (1. 2 -1. 4 mm) with matrix for low temperature measurements (polyethylene: sample: : 8: 1) pure sample pellets ( 0. 3 - 0. 7 mm) for room temperature measurement – to observe distinct peaks

Particle size – ESEM measurement Submicron particle size – minimise scattering effect on observed spectra

Far-infrared absorption in Glucose

Far-infrared absorption in Glucose D-Fructose L-Glucose D-Glucose

Dependence on crystallanity Intermolecular vibrational modes

Absorption in molecule containing glucose structure

Absorption in molecule containing glucose structure Sucrose L-Glucose absorption tend to depend on molecular environment

L-Glucose - absorption peaks at low temperature many distinct absorption peaks at low temperature

We observed terahertz absorption as a result of intermolecular interaction & also dependence on structural change in a molecule ……… in other molecules?

Far-infrared absorption in Uric Acid

Far-infrared absorption in Uric Acid Allantoin Uric Acid structural dependence of absorption

Temperature dependence Uric Acid Allantoin stronger temperature dependence in allantoin change in energy surfaces of molecules at low temperature

Uric Acid - absorption line profile change in position and width of peaks with temperature

Conclusions ØDemonstrated use of THz-TDS to study far-infrared response of some isomeric and derived structures of glucose and uric acid ØObserved absorption due to collective intermolecular modes ØStrong temperature and structural dependence of absorption ØTheoretical model analysis required to understand the underlying dynamics

Acknowledgements EPSRC Royal Society Toshiba Research Europe Association of Commonwealth Universities and thanks to Dr. M. B. Johnston Dr. A. Dowd