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

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, gu462/fulltext.pdfhttp://springer.metapress.com/content/jm gu462/fulltext.pdf

Building blocks for containers: amphiphiles Surfactant Tail Surfactant 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 = 220  90 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) 42  C 48  C

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