Restricted diffusion and release of aroma molecules from sol-gel-made porous silica particles.
The aim of the current study is to predict the release kinetics of organic molecules entrapped in sol-gel-made silica particles using both pulsed field gradient-nuclear magnetic resonance (PFG-NMR) techniques and model calculations to describe restricted diffusion. The macroscopic release profile of aroma molecules from sol-gel-made particles is measured directly by UV-VIS spectroscopy, while the release kinetics are calculated by the Crank equation. The microscopic restricted pore diffusion coefficient of the aroma molecules in the Crank equation is obtained in situ by pulsed field gradient (PFG) magic angle spinning (MAS) nuclear magnetic resonance (NMR). Furthermore, restricted pore diffusion coefficients obtained by model calculations are in agreement with those measured by PFG-MAS-NMR, indicating the potential of the latter for characterization and screening of encapsulation formulations. Measured and calculated release profiles agree within experimental error.
Veith
Susanne R
SR
Particle Technology Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstr. 3, ML F25, 8092 Zurich, Switzerland.
Hughes
Eric
E
Pratsinis
Sotiris E
SE
D004058:Diffusion; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D005782:Gels / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D009812:Odorants / Q000032:analysis*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013678:Technology, Pharmaceutical / Q000379:methods
D005782:Gels; D012822:Silicon Dioxide