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Juliette RUCHMANN, ESPCI, Paris, France Macro 2008, Taipei, June 29 - July 4

Photosensitive complexes of hydrophobically modified polymers, micelles of surfactants and enzymes. Juliette RUCHMANN, ESPCI, Paris, France Macro 2008, Taipei, June 29 - July 4. Stimuli-responsive systems of polymer and surfactant.

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Juliette RUCHMANN, ESPCI, Paris, France Macro 2008, Taipei, June 29 - July 4

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  1. Photosensitive complexes of hydrophobically modified polymers, micelles of surfactants and enzymes. Juliette RUCHMANN, ESPCI, Paris, France Macro 2008, Taipei, June 29 - July 4

  2. Stimuli-responsive systems of polymer and surfactant understanding of the interaction between polymer and surfactant Polymer hydrophilic/ hydrophobic stimuli: pH, T°, light … protein refolding sol/gel transition association polymer / surfactant multiple applications

  3. Light-stimulated association h non invasive and focused stimuli • photo-polymer + non responsive surfactant • macroscopic response to light • study of physico-chemical parameters

  4. Azobenzene-modified polymer O O H 9 - 1 0 C H 8 1 7 Structural parameters • chain length (Mn) small: 7,500 g/mol long: 42,000 g/mol or 60,000 g/mol • amount of modificationx = 1 - 5% NMR spectroscopy UV-visible Irradiation UV : 365 nm blue : 436 nm cis Surfactant TX 100 trans 42_3.5C6azo x = 3.5% / Mn=42,000g/mol

  5. Light-responsive complexes Static light scattering 1/ mixture = complexes formation 2 3 1 (A.U.) 2/ UV light = partial photo-dissociation mixture 42_3.5C6azo UV light Blue light TX 100 in the dark 3/ Blue light = re-association reversible photo-association / photo-dissociation several cycles for hours J. Ruchmann, S. Fouilloux, C. Tribet, Soft Matter, in press

  6. Light-responsive complexes Black / Blue trans azobenzene (100% black / 80% blue) = hydrophobicity maximum association with lipophilic core of the micelles UV (365nm) blue (436nm) UV cis azobenzene (80% UV) = more polar form decrease of the affinity for the micelles

  7. Transfer of the azobenzene from water into the micelles [azo] Abs Δ = = A BOUND τ [azo] [azo] TOT TOT ΔAbs 42_3.5C6azo with TX100 42_3.5C6azo UV visible spectrophotometry (O.D.) boundazobenzene

  8. Necklace composition binding isotherm Electrophoresis neutral reference complexes (anionic) TX100 (neutral) continuous injection bound surfactants

  9. 3 regimes of association 1 2 3 anti-cooperative binding tight association no association azo bound << 1 TX100 bound azo bound # 1 TX100 bound bound azobenzenes bound surfactants cmc

  10. Light-responsive complexes h h black/blue black/blue UV UV 2 3 42_5C6azo Electrophoresis blue irradiation UV irradiation 60% dissociation light-response in a large range of compositions

  11. Influence of different parameters small chain length 60% photo-dissociation 7.5_4C6azo 42_5C6azo 30% photo-dissociation TX 100bound/polymer (g/g) 1% modification low ionic strength 70% photo-dissociation almost no association 42_5C6azo 42_1C6azo [TX 100]free (g/L) [TX 100]free (g/L)

  12. Applications hn hn AMPs + neutral surfactants  reversible photo-control of emulsion S. Khoukh, et al., Chemphyschem, 2005. 6(10), 2009-2012 AMPs + protein (BSA)  photo-responsive physical gels G. Pouliquen and C. Tribet, Macromolecules, 2006. 39(1), 373-383 J. Ruchmann, S. Fouilloux, C. Tribet, Soft Matter, in press

  13. Protein refolding • AMPs + enzyme (BCA) no aggregation association soluble complexes unfolded protein REFOLDING + refolded protein dissociation

  14. Protein refolding dissociation + + association quenching no quenching Fluorescence

  15. CONCLUSION photo-control of association/dissociation with micelles and more generally with hydrophobic colloids (proteins …) Christophe TRIBET Agnès PALLIER Sarah FOUILLOUX Acknowledgements ANR-06-BLAN-0174  and BLAN07-3_190727 French ministery of research

  16. 3 regimes h h h cmc 1 2 3 

  17. Association with surfactants mixture TX 100 Surfactant 42_3.5C6azo TX 100 O O H 9 - 1 0 C H 8 1 7 Rh(complexes) ≈ Rh(polymer isolated chains) Rh(complexes)BLACK ≈ Rh(complexes)UV • well define complexes • no aggregation

  18. AMP multiple association onto an hydrophobic cluster. TΔSloop + ΔGazo < 0 Kass • balance between : • loop free energy • free energy of transfer of azobenzene between water and the micelle

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