Field Theoretic Simulations of Complex Coacervates

Transcription

1 FieldTheoretic Simulations of Complex Coacervates Debra J. Audus Glenn H. Fredrickson CFDC 2009 Annual Meeting

2 Contents Introduction/Motivation Theory and the Model Polyelectrolyte Phase Diagrams Theoretical Experimental Future Work

3 Complex Coacervation Salt (optional) Charged Polymers Complex Coacervate Cooper et al. Curr Opin Coll. & Interf. Sci. 10, 5278 (2005)

4 Applications Biopolymer characterization: Targeting specific DNA sequences Potential Carrier Systems: Complex surrounded by block copolymers B. Liu, G.C. Bazan, Proc. Nat. Acad., 102, (2005) Cements, glues and adhesives: Natural glue produced by Sandcastle worms Thünemann et al, Langmuir 16, (2000) Biopolymer characterization: Measuring DNA Concentration H. Zhao, C. Sun, R.J. Stewart, J.H. Waite, The Journal of Biological Chemistry, 280, (2005) J.W. Hong, W.L. Hemme, G.E. Keller, M.T. Rinke, G.C. Bazan, Advanced Materials, 18, (2006)

5 Motivation O OH RCOOH H 2 0 RCOO H 3 0 n Poly(acrylic acid) (HCl)NH 2 Poly(allylamine hydrochloride) n RNH 2 (HCl) 2H 2 0 RNH 3 OH Cl H 3 0 RNH 3 OH RNH 2 H 2 0 RNH 3 OH RCOO RNH 3 RCOO H 2 0

6 Motivation Clear Solution Coacervate Coacervate droplets R. Chollakup, M. Tirrell and C. Eisenbach, Unpublished (2008)

7 System Components polycation species 1 polyanion species 2 water salt cations implicit salt anions species 3 species 4

8 The Model: Full FieldTheory Partition Function for a system of charged polymers and salt in implicit solvent Excluded Volume Interactions Electrostatic Interactions Single Chain Partition Function Salt Ion Partition Function

9 Previous Work 2D Simulations of Symmetric Charged Polymers without Salt MeanField Simulation Complex Langevin Simulation Fluctuations are required to predict Complex Coacervation Y.O. Popov, J. Lee, G.H. Fredrickson, Unpublished (2007)

10 Gaussian Approximation Excluded Volume Parameter Thermal de Broglie wavelength

11 Gaussian Approximation The Helmholtz Free Energy on depends on 4 dimensionless parameters and the overall Debye wavelength Inverse of the square of the Debye length for each species

12 Analytical limits In the dilute limit,. In the limit of large polymers and low salt,. R g1 R g2 κ 1 κ 1 R g1 R g2 Debye Huckel Result Same as published results J. Lee, Y.O. Popov, G.H. Fredrickson, J. Chem. Phys., 128 (2008)

13 Phase Equilibrium: Gibb s Ensemble n 1I, n 2I, V I n 1 n 1I, n 2 n 2I, VV I Phase I Phase II Constant n 1, n 2, V and T Results in a set of differential equations

14 Interpreting Experimental Results High Turbidity Low Turbidity Coacervate Use optical microscope and turbidity measurements to determine the existence of a coacervate Solution R. Chollakup, M. Tirrell and C. Eisenbach, Unpublished (2008)

15 Symmetric Polyelectrolytes without Salt One Phase Region Two Phase Region

16 Effect of Salt Coacervate Solution R. Chollakup, M. Tirrell and C. Eisenbach, Unpublished (2008)

17 Effect of Salt

18 Effect of Total Concentration

19 Polymer and Salt Partitioning

20 Temperature effects Critical Salt Concentration for 20 C An increase in temperature reduces the two phase envelope Critical Salt Concentration for 50 C R. Chollakup, M. Tirrell and C. Eisenbach, Unpublished (2008)

21 Polymer Dissociation and Salt

22 Future work hydrophilic

23 Future work hydrophobic hydrophilic

24 Acknowledgements Glenn Fredrickson, Matthew Tirrell, Claus Eisenbach, Rungsima Chollakup, Jonghoon Lee, Yuri Popov and Erin Lennon The Fredrickson group MRL CSP Technologies Fellowship Institute for Collaborative Biotechnologies