1. PHYSICAL CHEMISTRY AND COLLOID SCIENCE Co 2+ Pb 2+ Cd 2+ Interfaces in food science and biotechnology Polymers at interfaces Strategic programme Colloids and interfaces Biophysical Chemistry Environmental physical chemistry Work at physical chemistry and colloid science with bio- aspects Wageningen University Laboratory of physical chemistry and colloid science Dreijenplein 6, 6703 HB Wageningen, the Netherlands Frans.leermakers@wur.nlFrans.leermakers@wur.nl, Martien.cohenstuart@wur.nl

2. PHYSICAL CHEMISTRY AND COLLOID SCIENCE Laboratory of physical chemistry and colloid science Strategic topic in phys. chem. and coll. sci. Biophysical chemistry Phys. chem. of food and biotechnology Polymers at interfaces Environmental physical chemistry Approach: -systematic experiments with a focus on understanding (we prefer to use model systems) -theoretical modeling directed to understand experiments

3. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 1. Self-assembly of pluronic 121  polymersomes PEO n -PPO m -PEO n surfactants form unstable vesicles for n ~5 and m~60 (L121) We stabilize the vesicles by a PETA network and obtain stable nanocapsules with tunable size Below you see such capsules filled by fiber-forming protein. F. Li, T. Ketelaar, A.T.M. Marcelis, F.A.M. Leermakers, M.A. Cohen Stuart, E.J.R. Sudholter "Stabilization of polymersome vesicles by an interpenetrating polymer network" Macromolecules 40 (2007) 329-333. AFM images

4. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 2. SCF modeling of self-assembly Lipid membranes in bulk and at interfaces bending moduli, structure and thermodynamics Vesicles in bulk and at interfaces Protein-like inclusions in membranes We like to work on -pores in membranes -interaction of polycation with negatively charged membrane -asymmetric interaction of objects with membrane -steady-state membrane systems -vesicle to micelle transition by way of adding surfactants to lipids R.A. Kik, F.A.M. Leermakers, J.M. Kleijn "Molecular modeling of lipid bilayers and the effect of protein-like inclusions" Phys. Chem. Chem. Phys. 7 (2005) 1996-2005.

5. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 3. Self-consistent field modeling Core-shell particles with PE corona Janus micelles composed of tri-block copolymers A n -B m -C n with A, C hydrophilic B hydrophobic We like to work on: -fluctuation in micelle size  driving force -self-assembly driven by electrostatic interactions -understand the formation of tubular vesicles -do more work on micellar shape transitions in micelles with PE corona

6. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 4. Micelles formed by attraction of + and  charges Generic idea is make micelles with water soluble compounds by mixing anionic block and neutral block M n -A m cationic block and neutral blockP n -B m when  AB > 0 Janus micelles can form I.K. Voets, A. de Keizer, P. de Waard, P.M. Frederik, P.H.H. Bomans, H. Schmalz, A. Walther, S.M. King, F.A.M. Leermakers, M.A. Cohen Stuart "Double-faced micelles from water-soluble polymers" Angew. Chem. Int. 45 (2006) 6673-6676. PAA 42 -b-PAAm 47 P2MVP 42 -b-PEO 446

7. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 5. Protein-copolymer complexes Enzyme encapsulation,targeting, controlling activity ++ enzyme - - - + + + + + + + + + + + + + - - - - - - - - - + + - - - - - - + + PAA-PAM + lysozym: light scattering + +

8. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 6. Micelles made by complexation with reversible polymers Metal-bisligand coordination complexes are self- assembled supramolecules that have residual (negative) charge. Admixing with oppositely charged copolymers gives hierarchical self-assembly Cryo-TEM images of coacervate core micelles formed in the mixed systems a), f- = 0.5 PMVP 41 -PEO 204 / Zn-L 2 EO 4 b), f- = 0.5 A-B-A/ Zn-L 2 EO 4 mixed system. f- is the negative charge fraction in the mixed system. A-B-A= polyaminoacid block copolymer, A = neutral block, B = positively charged block Yan, Y.; Besseling, N. A. M.; de Keizer, A.; Marcelis, A. T. M.; Drechsler, M.; Cohen Stuart, M. A. Angew. Chem. Int. Ed. 2007, 46, published on line Feb.2, 2007

9. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 7. Brushes: experiments and SCF models Brushes as anti-fouling surfaces PEO, polysacharide (sweet) Polydisperse polymer brushes Proteins in polyelectrolyte brushes F.A.M. Leermakers, M. Ballauff, and O.V. Borisov “On the mechanism of uptake of globular proteins by polyelectrolyte brushes: a two-gradient self consistent field analysis” Langmuir 2007 in print

10. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 8. Polypeptide synthesis by yeast cells

11. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 8. Tri-block copolyelectrolytes from yeast -available on gram scale -homo-disperse, chiral and pure -pH responsive gel formation (driven by  -sheet formation)

12. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 9. Measurements of forces by colloid probe AFM We have an interest in measuring forces on the nanoscale -depletion forces -in non-adsorbing polymer systems -in equilibrium polymer systems -deformation of vesicles (nano-capsules) -electrostatic interactions, -polymer mediated forces -effect of surface modification. EHUT + some DHUT Silica+C18 cyclohexane W. Knoben, N.A.M. Besseling, M.A. Cohen Stuart "Long-range depletion forces induced by associating small molecules" Phys. Rev. Lett. 97 (2006) 068301/1-4.

13. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 10. Summary experimental SCF-modeling (and a little bit MC simulations) Strong in thermodynamic analysis Strong in electrified interfaces Scattering (light, neutrons, xrays) Reflectometry (dynamic adsorption studies) /ellipsometry Calorimetry AFM including colloidal probe Titrations and other analytical tools, surface characterisation Microscopy (light, confocal, TEM …) NMR Langmuir trough

14. PHYSICAL CHEMISTRY AND COLLOID SCIENCE 10. Summary systems Self-assembly in aqueous systems based on hydrophobic driving force electrostatic driving force metal-ligand mediated assembly with help of polymer network Applications are bio-inspired responsive systems preference to study equilibrium systems interest in steady state conditions Open eye for applications