Selvorganisering i nanosystemer eller Systemer selvorganiseret på nanometer længde skala, Department of Chemistry and inano Center University of Aarhus
Examples of selforganized systems All living organisms but very complex!
Outline Detergents and surfactants Detergentprotein complexes Template systems Microemulsions for drug delivery Block copolymers
Understanding the systems is important: Disorder in biological systems => deceases Stability shelf lifetime who want to buy a product in a twophase state?
Relevant interactions Hydrogenbonding: polar/non polar the hydrophobic effect Electrostatic interactions Van der Waals/London interactions
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. 1973 The Hydrophobic Effect: Formation of Micelles and Biological Membranes. John Wiley & Sons, New York.
Amphiphilic Molecules = surfactants, detergents. hydrophobic alkylchain hydrophilic headgroup Micelle
Types of surfactants Anionic SDS= sodium dodecyl sulphate Nonionic C12E5 = pentaoxyethylene dodecyl ether C12mal = ndodecyl βdmaltopyranoside C10G1 = ndecyl βdglucopyranoside Na S
SDS micelle
Experiment SDS solution: Electrolyte solution Conductivity As a function of concentration
Conductivity of SDS solution 2 SDS CMC = critical micelle concentration 1.8 1.6 Conductivity (ms / cm) 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 0.02 0.04 0.06 0.08 Conc SDS (mol / L) Bente Olsen, Petra Bäverbäck,
BSA detergent complexes Bovine Serum Albumine SDS anionic DTAB cationic M = 66 000, 580 amino acids residues. ph 7 slightly negatively charged
Protron titration curve isoelectric point ph of solution
Why: SDSPAGE for protein mass determination or purification How much SDS binds?
Experiments Conductivity Absorbance/turbidity (light scattering)
Experiments BSA SDS: Only hydrophobic interaction Electrostatic repulsion => Wellseparated particles => Conductivity BSA DTAB: Electrostatic attraction => Charge neutralization => Precipitation => Turbidity
Conductivity of BSASDS mixture 2.5 2 start of binding Conductivity (ms / cm) 1.5 1 0.5 end of binding 0 0 0.5 1 1.5 2 2.5 g SDS / g BSA
BSA mercaptoethanol Partly denaturated
BSA mercaptoethanol a little SDS
BSA mercaptoethanol more SDS
BSA mercaptoethanol even more SDS
Conductivity of BSASDS mixture 0 0.5 1 1.5 2 2.5 0 0.5 1 1.5 2 2.5 g SDS / g BSA Conductivity (ms / cm) start of binding end of binding Only about 10% of chain is covered
BSA DTAB complexes Increasing DTAB concentration Absorbance 2.000 1.500 1.000 0.500 0.000 0.500 Absorbanse 0 5 10 15 g DTAB / g BSA x 2
BSA mercaptoethanol a little DTAB Electrostatic binding
BSA mercaptoethanol more DTAB Electrostatic binding and bridging at charge neutralization => turbidity
BSA mercaptoethanol even more DTAB Electrostatic repulsion and stabilization
BSA DTAB complexes Absorbance 2.000 1.500 1.000 0.500 0.000 0.500 Absorbanse 0 5 10 15 g DTAB / g BSA x 2 Charge neutralization the charge of BSA can be estimated! (taking disassociation degree into account)
High concentrations: Liquid crystalline phases Lamellar phase (Inverse) Hexagonal phase Cubic phase
Synthesize silica in the holes Transmission electron microscopy
Order can be studied by xray diffraction Bragg s law: λ=2 d sinθ => d=λ/(2 sinθ) d large => small angles!
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
The experimental setup: Department of Chemistry SAXS setup
Synthesize silica in the holes hexagonal structure of cylindrical holes
New materials: Templating methods provide specially designed material with unique properties, which do not exist in Nature!
Microemulsion (nano!) Amphiphilic molecule hydrophobic hydrophilic lecithin oil/ (tri)glyceride 2050 nm cosurfactant (nonionic surfactant )
Delivery of active molecules In vitro Stability Extended blood circulation Targeting Bioavailability In vivo Many new drugs are insoluble in water!
120 m 2 0.53.5 hr 34 hr 0.3 m 2 0.1 m 2 bases 1 3 d acids Stomach Jejunum Ileum Colon ph 1.42.1 3 7 4.4 6.6 5.2 6.2 6.8 8.0 6.8 8.0 5 8 5 8 fasted state fed state
Release principles
Encapsulation in oilinwater microemulsions: Slower release in the mouth For controlled release in GI tract: Influence of gastric acids, enzymes, bile, food..
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 0.045 mmole/min NaOH Impulse pump Sesame oil Maisine 351 Formulation 30.0 30.0 magnetic stirrer Cremophor Ethanol 30.0 10.0
Newly formed particles Cryo TEM 40 nm diameter SAXS 40 nm diameter
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 ) 0.1 0.01 0.001 0.1 1 q (nm 1 ) 0 20 40 60 80 Time (min) 100 Lamellar phase forms fast! Hexagonal phase forms later during digestion
Formulation evolution
Polymer chain Diblock copolymer
Small differences in interactions are amplified due to the large molar mass Mesoscopic phase separation Structure depends on relative mass
SBS Rubber
SBS: Thermoplastic elastomer Very easy to process physical cross links (conventional rubber is crosslinked chemically by vulcanization)
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
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
Hexagonal cylinders SAXS (Aarhus) sample from KA thesis 0.0413 Å 1 100 15.2 nm intensity [a.u.] 10 0.0715 Å 1 1 0.109 Å 1 1 3 ½ 4 ½ 7 ½ 0.05 0.10 0.15 0.20 q [Å 1 ]
Molecular sieve Fill with metals: nanowires Align by shear: Monodomaine Thin film
Summary Detergents, micelles, CMC Detergent protein complexes Micellar liquid crystalline phase as template Microemulsions for drug delivery Block copolymer mesoscopic ordering Polymeric sieves