Biomass Fundamentals Modules 19: Higher Order Functionality in Biomass: Surface Active Materials A...
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Biomass Fundamentals Modules 19: Higher Order Functionality in Biomass: Surface Active Materials A capstone course for BioSUCCEED: Bioproducts Sustainability: a University Cooperative Center of Excellence in EDucation The USDA Higher Education Challenge Grants program gratefully acknowledged for support
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Transcript of Biomass Fundamentals Modules 19: Higher Order Functionality in Biomass: Surface Active Materials A...
Biomass Fundamentals
Modules 19: Higher Order Functionality in Biomass:Surface Active Materials
A capstone course for
BioSUCCEED:
Bioproducts Sustainability: a University Cooperative Center of Excellence in EDucation
The USDA Higher Education Challenge Grants program gratefully acknowledged for support
This course would not be possible without support from:
USDA
Higher Education Challenge (HEC) Grants Program
www.csrees.usda.gov/funding/rfas/hep_challenge.html
Article of Interest for Discussion
• “Comparison of the Leakage of Carboxyfluorescein from Symmetric and Asymmetric-Acyl Chain Phospatidylcholine Vesicles” – Wiedmann, Timothy S.; Salmon, A.; Perkins, Walter R. Pharm. Res. 1993, 10, 147-151.
• http://springer.metapress.com/content/jm857702236gu462/fulltext.pdf
Building blocks for containers: amphiphiles
Surfactant TailSurfactant Head
Surfactant Monomers
Micelle
Structure of a Vesicle
• Amphiphiles used to make it• Grossly – bilayer structure
versus micelle• Unilamellar sphere (SLV) vs
MLV (multilamellar)• Hydrophilic core & bulk• Sandwich is hydrophobic
Vesicles as containers
• Modify them by employing amphiphiles that moderate permeability
• Use symmetric & asymmetric amphiphiles• Make mixed chain, partial interdigitated
bilayer
Symmetric amphiphile (16,16 PC)
Asymmetric amphiphile (20,12 PC)
18
10
DSC profiles for vesicles (multilamellar)
• High sensitivity DSC• 20/hr scan rate• Gel-to-liquid crystalline
transitions different• Mean diameters = 22090
nm & 210 85 nm for 16/16 PC & 20/12/ PC, respectively
16/16 PC
20/12 PC
Extruded dispersions
Multilamellar dispersions
Time dependence of guest release
• Leakiness originates from gel-to-liquid transitions
• Carboxyfluorescein is the guest molecule
• In the 16/16 PC (circles), there is more release than 20/12 PC (squares)
42C
48C
Release of guest (carboxyfluorescein) as a function of temperature
• In 20/12 PC, there is little correlation between % release and temperature (closed circles)
• In 16/16 PC, there is definite dependency on T
