Multicomponent hollow tubules formed using phytosterol and gamma-oryzanol-based compounds: an understanding of their molecular embrace.
The formation kinetics of self-assembling tubules composed of phytosterol:gamma-oryzanol mixtures were investigated at the Canadian Light Source on the mid-IR beamline using synchrotron radiation and Fourier transform infrared spectroscopy (FT-IR). The Avrami model was fitted to the changing hydrogen bonding density occurring at 3450 cm(-1). The nucleation process was found to be highly dependent on the molecular structure of the phytosterol. The nucleation event for cholesterol:gamma-oryzanol was determined to be sporadic whereas 5alpha-cholestan-3beta-ol:gamma-oryzanol and beta-sitosterol:gamma-oryzanol underwent instantaneous nucleation. One-dimensional growth occurred for each phytosterol:gamma-oryzanol mixture and involved the evolution of highly specific intermolecular hydrogen bonds. More detailed studies on the cholesterol:gamma-oryzanol system indicated that the nucleation activation energy, determined from multiple rate constants, obtained using the Avrami model, was at a minimum when the two compounds were at a 1:1 weight ratio. This resulted in drastic differences to the microscopic structures and affected the macroscopic properties such as turbidity. The formation of the phytosterol:gamma-oryzanol complex was due to intermolecular hydrogen bonding, which was in agreement with the infrared spectroscopic evidence.
Rogers
Michael A
MA
Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK, Canada, S7N5A8. michael.rogers@usask.ca
Bot
Arjen
A
Lam
Ricky Sze Ho
RS
Pedersen
Tor
T
May
Tim
T
D002152:Calorimetry, Differential Scanning; D006860:Hydrogen Bonding; D007700:Kinetics; D008853:Microscopy; D010666:Phenylpropionates / Q000737:chemistry*; D010840:Phytosterols / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
D010666:Phenylpropionates; D010840:Phytosterols; C013172:gamma-oryzanol