Deck C Flashcards
Micelle definition
thermodynamic, random, and non-hierarchical process with molecular length scale.
Main micelle formation driving force
Hydrophobic interactions
Micelle formation process (increasing surfactant concentration)
- Surface and diluted
- Surface and paired dilution
- Monolayer surface (1st) and micelle formation (CMC)
- Monolayer surface and aggregate formation (CMC+)
CMC
Critical Micelle Concentration
The monomer concentration where the first micelle begins to appear
Important micelle parameters
- CMC
- Aggregation number
- Degree of counterion binding on the surface of micelles
CMC range and Micelle diameter
micro to milli molar
2-20 nm
Aggregation number
The number of surfactant or polymer molecules within a micelle (10-10,000)
Degree of Counterion binding
The ratio of counterion bound on the micelle surface to the whole concentration of counterion in the system
CMC Calculation of Mixed Micelle
1/CMC = MoleFraction_A/CMC_A + MoleFraction_B/CMC_B
HLB Calculation of Mixture
HLB = [MoleFraction_A*HLB_A + MoleFraction_B * HLB_B]/M_mix
Qualities of a bilayer monomer
Usually 2 tails
Needs to be cylindrical
Bolaform Surfactant
two head groups connected by hydrophobic tails
Bilayer formation process
Well defined CMC
Finite size
Thermodynamically driven
All micelles for a given surfactant are relatively the same size which is dictated by the size of the polymer.
What determines the unique planar-like structure of a bilayer
molecular geometry of its monomer
Vesicle size
20 nm - 50 um
Thickness of each single layer is 3-5 nm
Vesicle are usually classified in three groups based on ______
Based on size and geometry
Unilamellar
Single lipid bilayer
Small < 100 nm
Large > 10 nm
Multilamellar
Multiple lipid bylayers
Either concentric or verosome (side by side donuts in one large donut)
Liposome
Vesicle composed solely of lipids
i.e. phospholipid, triglyceride, glycolipid
Niosome
Vesicle formed solely by nonionic surfactants
Drug delivery 0.1-2 um
Polymersome
Vesicle formed solely by amphiphilic block copolymers
0.05-5 um
Both hydro-phyllic-phobic drugs
Types of vesicles
Liposome, Niosome, Polymersome, Ethosome, Transfersome, Phytosome, Cubosome
Why use liposomes for drug delivery?
Protects from immune system
Goes through the gut
Can attach to cell’s lipid bilayer.
Ethosome
Ethanolic phospholipid vesicle used mainly for transdermal delivery of drugs
20-45% ethanol
Transfersome
Elastic or deformable vesicle that can squeeze throng junctions.
Phytosome
complex of natural active ingredient and a phospholipid.
Drug is in lipid layer, not inner sphere.
Cubosome
nanoparticles but instead of the solid particles they are liquid crystalline particles of certain surfactant with proper ratio of water
Liposome, Nanoemulsion, Lipid Nanoparticle
Bilayer w/ aqueous core, Monolayer w/ liquid lipid core, Monolayer w/ solid lipid core
Emulsion
mixture of two or more liquids that are normally immiscible
Emulsifying agent
substances added to an emulsion to prevent the coalescence of the globules of the dispersed phase.
Emulsions can be classified based on the ____ phase or the ____ of the liquid droplets.
Dispersed
Size
Common types of emulsifiers
Surfactants: Anionic, Nonionic, Cationic.
Soot, Silica, Clay
Micro- vs. Macro- emulsifiers
Micro : Only surfactants
Macro : Other types too (i.e. polymers)
W/O vs. O/W
Water in oil vs. Oil in water
Depends on HLB
High HLB for W/O and Low HLB for O/W
