Selv-organisering i nanosystemer. eller. Systemer selv-organiseret på nanometer længde skala

Transcription

1 Selvorganisering i nanosystemer eller Systemer selvorganiseret på nanometer længde skala, Department of Chemistry and inano Center University of Aarhus

2 Examples of selforganized systems All living organisms but very complex!

3 Outline Detergents and surfactants Detergentprotein complexes Template systems Microemulsions for drug delivery Block copolymers

4 Understanding the systems is important: Disorder in biological systems => deceases Stability shelf lifetime who want to buy a product in a twophase state?

5 Relevant interactions Hydrogenbonding: polar/non polar the hydrophobic effect Electrostatic interactions Van der Waals/London interactions

6 The hydrophobic effect: Placing hydrocarbon chains in water The water in the neighborhood is ordered (= entropy cost) Less ordered water: Entropy gain = Lowering of free energy Tanford, Charles The Hydrophobic Effect: Formation of Micelles and Biological Membranes. John Wiley & Sons, New York.

7 Amphiphilic Molecules = surfactants, detergents. hydrophobic alkylchain hydrophilic headgroup Micelle

8 Types of surfactants Anionic SDS= sodium dodecyl sulphate Nonionic C12E5 = pentaoxyethylene dodecyl ether C12mal = ndodecyl βdmaltopyranoside C10G1 = ndecyl βdglucopyranoside Na S

9 SDS micelle

10 Experiment SDS solution: Electrolyte solution Conductivity As a function of concentration

11 Conductivity of SDS solution 2 SDS CMC = critical micelle concentration Conductivity (ms / cm) Conc SDS (mol / L) Bente Olsen, Petra Bäverbäck,

12 BSA detergent complexes Bovine Serum Albumine SDS anionic DTAB cationic M = , 580 amino acids residues. ph 7 slightly negatively charged

13 Protron titration curve isoelectric point ph of solution

14 Why: SDSPAGE for protein mass determination or purification How much SDS binds?

15 Experiments Conductivity Absorbance/turbidity (light scattering)

16 Experiments BSA SDS: Only hydrophobic interaction Electrostatic repulsion => Wellseparated particles => Conductivity BSA DTAB: Electrostatic attraction => Charge neutralization => Precipitation => Turbidity

17 Conductivity of BSASDS mixture start of binding Conductivity (ms / cm) end of binding g SDS / g BSA

18 BSA mercaptoethanol Partly denaturated

19 BSA mercaptoethanol a little SDS

20 BSA mercaptoethanol more SDS

21 BSA mercaptoethanol even more SDS

22 Conductivity of BSASDS mixture g SDS / g BSA Conductivity (ms / cm) start of binding end of binding Only about 10% of chain is covered

23 BSA DTAB complexes Increasing DTAB concentration Absorbance Absorbanse g DTAB / g BSA x 2

24 BSA mercaptoethanol a little DTAB Electrostatic binding

25 BSA mercaptoethanol more DTAB Electrostatic binding and bridging at charge neutralization => turbidity

26 BSA mercaptoethanol even more DTAB Electrostatic repulsion and stabilization

27 BSA DTAB complexes Absorbance Absorbanse g DTAB / g BSA x 2 Charge neutralization the charge of BSA can be estimated! (taking disassociation degree into account)

28 High concentrations: Liquid crystalline phases Lamellar phase (Inverse) Hexagonal phase Cubic phase

29 Synthesize silica in the holes Transmission electron microscopy

30 Order can be studied by xray diffraction Bragg s law: λ=2 d sinθ => d=λ/(2 sinθ) d large => small angles!

31 Schematic setup for smallangle xrays scattering Source Monochromator 2θ q q 4π sinθ / λ Bragg s law: λ=2 d sinθ => d=λ/(2 sinθ) = 2 π / q

32 The experimental setup: Department of Chemistry SAXS setup

33 Synthesize silica in the holes hexagonal structure of cylindrical holes

34 New materials: Templating methods provide specially designed material with unique properties, which do not exist in Nature!

35 Microemulsion (nano!) Amphiphilic molecule hydrophobic hydrophilic lecithin oil/ (tri)glyceride 2050 nm cosurfactant (nonionic surfactant )

36 Delivery of active molecules In vitro Stability Extended blood circulation Targeting Bioavailability In vivo Many new drugs are insoluble in water!

37 120 m hr 34 hr 0.3 m m 2 bases 1 3 d acids Stomach Jejunum Ileum Colon ph fasted state fed state

38 Release principles

39 Encapsulation in oilinwater microemulsions: Slower release in the mouth For controlled release in GI tract: Influence of gastric acids, enzymes, bile, food..

40 Dimitrios G. Fatouros,*, G. Roshan Deen, Lise Arleth, Bjorn Bergenstahl, Flemming Seier Nielsen,, Anette Mullertz The simulated stomach Substance Bile salt Lecithin Initial concentration 5 mm 1 mm titrator ph meter Pancreatic lipase Trizmamaleate 800USP units/ml 2 mm CaCl2 temperature controller Na Ca2 150 mm mmole/min NaOH Impulse pump Sesame oil Maisine 351 Formulation magnetic stirrer Cremophor Ethanol

41 Newly formed particles Cryo TEM 40 nm diameter SAXS 40 nm diameter

42 STRUCTURAL CHANGES OF SELF NANO EMULSIFYING DRUG DELIVERY SYSTEMS (SNEDDS) DURING IN VITRO LIPID DIGESTION MONITORED BY SMALLANGLE XRAY SCATTERING Dimitrios G. Fatouros,*, G. Roshan Deen, Lise Arleth, Bjorn Bergenstahl, Flemming Seier Nielsen,, Anette Mullertz 1 I (cm 1 ) q (nm 1 ) Time (min) 100 Lamellar phase forms fast! Hexagonal phase forms later during digestion

43 Formulation evolution

44 Polymer chain Diblock copolymer

45 Small differences in interactions are amplified due to the large molar mass Mesoscopic phase separation Structure depends on relative mass

46 SBS Rubber

47 SBS: Thermoplastic elastomer Very easy to process physical cross links (conventional rubber is crosslinked chemically by vulcanization)

48 Making exotic materials: Nanoporous Elastomers Based on Polymer Selfassembly Martin E. Vigild, Sokol Ndoni and Rolf H. Berg, Danish Polymer Centre Selective Etching PDMS Etching air Mesomorphic block copolymer Glassy matrix Nanoporous Material

49 HFetching of PDMS m Si O Si n m Si F 3n HF n H 2 OHF (n1) F 2 Si(CH 3 ) 2 FSi(CH 3 ) 3

50 Hexagonal cylinders SAXS (Aarhus) sample from KA thesis Å nm intensity [a.u.] Å Å ½ 4 ½ 7 ½ q [Å 1 ]

51 Molecular sieve Fill with metals: nanowires Align by shear: Monodomaine Thin film

52 Summary Detergents, micelles, CMC Detergent protein complexes Micellar liquid crystalline phase as template Microemulsions for drug delivery Block copolymer mesoscopic ordering Polymeric sieves