Upload
clinton-gomez
View
51
Download
1
Embed Size (px)
DESCRIPTION
Applications of Polymerized Vesicles. Seung-Woo Son, Complex System and Statistical Physics Lab. Motivation : Nature and Membranes. What is a membrane structure ?. Simply lipid bilayers or vesicles !. Introduction : Glossaries of Soft Matters. What is Vesicles? - PowerPoint PPT Presentation
Citation preview
• What is Vesicles?– Spherical closed bilayer structures– Surfactants comprising two alkyl chains and a cationic polar head (a
mmonium, phosphate or zwitterion) cf.) micelles, microemulsions, bilayers
• Liposomes ( a special case of vesicles )– Vesicles formed from naturally occurring lipid molecules.
• Lipid : 비극성 유기용매의 추출에 의해 세포나 조직으로부터 분리되는 자연계에
존재하는 유기분자 ( 종류 : 지방 , 왁스 , 콜레스테롤 , 스테로이드 )
* Other useful expression…– In vivo : 생체에서…
– In vitro : 시험관에서…
Introduction : Glossaries of Soft Matters
Physics of Soft Matters
• Micelles, bilayers, vesicles and biological membranes
– Self-assembly of certain amphiphilic molecules– Association colloids or complex fluids– Soft, flexible (fluid-like) unlike solid particles, rigid macromolecules
(ex.DNA)– Van der Waals force, hydrophobic, hydrogen-bond, screened electro
static interactions etc.(not covalent bond or ionic bond)– Solution conditions(electrolyte concentration, pH, temperature, etc.)
change the size and shape of molecule aggregates.
• Ref. Jacob N. Israelachvili, “Intermolecular and Surface Forces” Ch 16, 17
Special Character of Vesicles
• Diameter ~ 10nm, thickness 4~5nm spherical water-filled pockets
• Several weeks lifetime– Great kinetic stability – Lower surfactant exchange rate– Higher number of surfactant molecules
Spherical micelles Microemulsions Vesicles
Mean molecular weight
1-3 104 105 - 106 > 107
Aggregation number
20 -100 103 104 - 105
Diameter ( Å ) 30 - 60 50 - 500 300 - 5000
Monomer exchange rate (s)
10-5 10-5 > 1
Aggregate lifetime 10-3 – 1 s Very long Week, month
Dilution in water Destroyed Altered Stable
Polymerization of Vesicles
• The aim of polymerization is to fix the structure– To observe the shape of vesicle, to measure the size– Control the size, rigidity, permeability– Actually unlimited lifetime(several month) : greater
stability– To clarify the mechanism of vesicle fusion
Applications of Polymerized Vesicles (1) : DDS
• Active molecule transport– Pharmacology : selectively carry a compound
to a preselected site in the organism.– pH, temperature, photochemical isomerisation,
enzymes, etc.
Applications of Polymerized Vesicles (2) : catalysts
• Ideal medium for the formation of small and uniform colloidal particles of metals or oxides.– Potassium tetrachloroplatinatr ( K2PtCl4 ) + polymerisable surfactan
ts : extremely efficient colloidal platinum catalyst.
• Artificial photosynthesis– Photochemical solar-energy conversion using colloidal semiconducto
r– Decomposing water
Summaries
• Vesicles 의 모양와 성질에 대해서
• Polymerization 을 연구해야 하는 이유
• Polymerization 방법들
• Polymerized vesicles 의 응용