Lecture 13-14.pdf - MCDB/CHEM 145/151 lecture 13 Complex...

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MCDB/CHEM 145/151 lecture 13 Complex coacervates Sancastleworm cement Surface energy Coacervate problem #5
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BSA (FITC labeled) Poly(allyldimethylammonium chloride) @ pH 9.0 and I = 0.1 M NaCl0 Cooper et al (2005) Curr Opin Coll. & Interf. Sci . 10, 52-78. Complex coacervation + + + - - -
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Coacervation characteristics Lower viscosity Viscosity - h coac [ h A + h B ]/10 ** Spontaneous spreading Interfacial energy - extremely low - < 1 mJ/m 2 Higher concentration [protein] coa = 10 x [protein] l Diffusion D o for H 2 O & biopolymers - higher than expected
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Surface tension Fluids and surface tension free energy/surface area g = mN/m =mNm/m . m = mJ/m 2 @20˚ and vapor pressure Water 72 N-propanol 23 Mercury 484 Octane 21 perFpentane 10 Solids & Critical surface energy g = erg/cm 2 free energy/surface area Fluid/fluid interfacial tension g = mJ/m 2 Liquid (2): Water(1) g H 2 O/Octane = 51 72+21-2 21x20 - 0 g g g g g g g
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Surface tension vs energy Surface tension f f f %G 25 35 45 f f f f 10.5 mEq KCl 7 mEq KCl 0 mEq KCl Gelatin-gum arabic 40˚C Bungenberg de Jong (1949) 72 mJ/m s H 2 0 High s High s Low s
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Interfacial tensions A A B B g w = 72.2 g w P = 50.2 g w d = 22 Underwater W A = 2{ g A d g w d - g A p g w p - g B d g w d - g B p g w p + g A d g B d + g A p g B p } g ab = g a + g b (no interaction) g ab = g a + g b - W A g ab = g a + g b - 2[ g d a g d b ] 1/2
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Wet adhesion - technologically formidable? 1 2 1 2
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Role in biochemistry?
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Oparin’s origin of life
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Polychætes are adhesive experts Phragmatopoma builds tubes with mineral particles washed in by the waves Each particle is caught, inspected, kissed with several dollops of adhesive mortar from the cement gland, and glued into the wall. ~30 sec set E i depends on conditions
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Requirements for Practical Adhesive Absence of weak boundary layers Water is a boundary layer and vital for life Fluid adhesive having g L < g C of substratum How to keep a fluid discrete within another fluid Formation of extensive interfacial molecular contacts Real surfaces are rough and wet Setting/ curing of adhesive How to prevent diffusive loss of cross-linker Schonhorn (1981) Adhesion in Cellulosic and Wood-based Composites. Ed. J. F. Oliver, Plenum
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Ventral view- Phragmatopoma CJ SUN (2005)
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Phragmatopoma cement : proteins w/ dopa & P- serine Pc-1; M = 18,240; pI = 9.74 YGCGVGIGC- AGGRCGGACG GK GYGYG G- K L GY GA YG KGG I GGYGYG KGC V GGYGYG GLG AGK------- L GGYGYG GS K C GGYGYG GQ K L GGYGYG GK K L GGYGY AAK K V GGYGYG AK K V GGYGYG AK K V GGYGYG AK K V GGYGYG AK K V GGYGYG AK K V GGYGYG AK K V GGYGYG VK K V GGYGYG --- Pc-2; M = 21,116; pI= 9.91 CGGAGG WRSGSCGG RWG HPAV ---- HKALGG Y G - G Y GA HPAV HAAV HKALGG Y G AGAYGAG AWG HPAV ---- HKALGG Y G AGA WG HPAV ---- HKALGG Y G - G Y GA HPAV H V AV HKALGG Y G AGACGHKT GG Y G G Y GA HP-VAV --- KA --A Y -NHGFN Y GANNAI K S T KRF GG Y GA HP - V - V K-- KA FSRGLSHGAY-AGSKAATGYGYGSG KA A GG Y G Y Pc-3; M = 30,000; pI = 2.5 (with phosphoserine groups) CCKRY SSSSY SSSSSS SSSSY SSSS SSSSY SSSSS SSSSY SSSSSS SSSSY SS SSSSY SSS SSSSY SSSSSS SSSSY SS SSSSY SSSSS SSSSY SSSSS SSSSY SSSSSS SSSSY SS SSSSY SSS SSSSY SS SSSS SSSSY SS SSSSY SSSSS SSSSY SSSSS SSSSY SSS SSSSY SS SSSSY SSSSSSS SSSSY SSS SSS SSSSY SS SSSSY SSSSS
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  • Spring '09
  • WAITE
  • Surface tension, Trigraph, Dopa, Waite

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