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Polymers, nanoparticles and phosphol...

Zhang, Liangfang.

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Polymers, nanoparticles and phospholipids.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Polymers, nanoparticles and phospholipids./
Author:	Zhang, Liangfang.
Description:	151 p.
Notes:	Adviser: Steve Granick.
Contained By:	Dissertation Abstracts International68-02B.
Subject:	Biophysics, General. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3250356

Polymers, nanoparticles and phospholipids.
Zhang, Liangfang.

Polymers, nanoparticles and phospholipids. - 151 p.

Adviser: Steve Granick.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.

We study various aspects of phospholipids and resolve around the interactions between polymers, nanoparticles and phospholipids. Two artificial phospholipid self-assemblies, supported lipid bilayers and liposomes, are employed to investigate how polymers and nanoparticles can be involved into the studies of phospholipids. More specifically, we explore how the translational diffusion of lipids in supported bilayers is affected by the adsorbed polymers at various surface coverage, molecular weight, and ionic strength. We also explore how nanoparticles, binding to the outer surface of liposome membranes, influence dynamical and structural properties of liposomes, for example, including vesicle fusion, membrane stability, permeability, biofunctionality and rigidity.Subjects--Topical Terms:

1019105
Biophysics, General.

Polymers, nanoparticles and phospholipids.
LDR:04888nam 2200301 a 45 001 940853
005 20110518
008 110518s2006 ||||||||||||||||| ||eng d
035 $a (UMI)AAI3250356
035 $a AAI3250356
040 $a UMI $c UMI
100 1 $a Zhang, Liangfang. $3 1264982
245 1 0 $a Polymers, nanoparticles and phospholipids.
300 $a 151 p.
500 $a Adviser: Steve Granick.
500 $a Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1144.
502 $a Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.
520 $a We study various aspects of phospholipids and resolve around the interactions between polymers, nanoparticles and phospholipids. Two artificial phospholipid self-assemblies, supported lipid bilayers and liposomes, are employed to investigate how polymers and nanoparticles can be involved into the studies of phospholipids. More specifically, we explore how the translational diffusion of lipids in supported bilayers is affected by the adsorbed polymers at various surface coverage, molecular weight, and ionic strength. We also explore how nanoparticles, binding to the outer surface of liposome membranes, influence dynamical and structural properties of liposomes, for example, including vesicle fusion, membrane stability, permeability, biofunctionality and rigidity.
520 $a We find when the flexible macromolecules adsorb at incomplete surface coverage, the translational diffusion of lipids splits into two populations; a fast mode characteristic of naked lipid diffusion coexists with a slow mode, whose magnitude scales inversely with the degree of polymerization of the polymer. Further investigations find that this dynamical heterogeneity is due to "slaved diffusion". That is, lipid molecules assemble to nanodomains induced by individual polymer chains which adsorb to their outer leaflet. Lipids contained within the domain will be slaved by the adsorbed polymer chain and diffuse collectively, while those lipids out of the domain will not be affected in the presence of polymer and diffuse freely as in naked bilayers. This provides a new mechanism to explain how nano-sized domains with reduced mobility arise in lipid membranes, and offers a reliable and idiographic picture helping to understand the mechanisms of lipid and protein diffusion related biological processes in lipid membranes. It also provides a new set of problems to polymer studies; the dynamical and structural properties of polymers on soft and responsive surfaces such as lipid bilayers instead of hard and frozen surfaces such as solid substrates.
520 $a Moreover, we study the phases and phase transitions of supported phospholipid bilayers. There are massive defects in the gel phase due to the considerable shrinkage of the area occupied by each lipid molecule in gel phase than in fluid phase. We find that the presence of cationic lipids can minimize differences in headgroup orientation between the fluid and gel phases. This in turn minimizes density mismatch between the fluid and gel phases, tending to stabilize the bilayer structure against defects when the bilayer passes from the fluid to the gel phase.
520 $a In addition, we find binding of charged nanoparticles to the outer surface of phospholipid liposomes produces particle-stabilized liposomes that repel one another and do not fuse. Subsequently, the volume fraction can be raised as high as &sim;50%, reversibly, still without fusion. In studies of liposome longevity, we verify the stability of particle-stabilized liposome suspensions with volume fraction up to 16% for up to 50 days, the longest period investigated. In contrast to the stabilized liposomes, the volume fraction of the same liposomes without nanoparticles is typically less than &sim;2% with a longevity of 4&sim;5 days. Fluorescent dyes are encapsulated within the particle-stabilized liposomes, without leakage. Although these particle-stabilized liposomes are stable against fusion, &sim;75% of the outer liposome surface remains unoccupied, which is still biofunctionalizable tested with ligand-receptor binding. This work not only provides a robust nanoparticle-liposome complex system which possesses many potential biomedical and biotechnological applications, but also offers new understanding and scholarship on the physical and biological characteristics of phospholipid liposomes such as membrane stability, permeability, rigidity, and biofunctionality. It also generates a new brand of colloids, which are soft, hollow and functionalizable compared with the conventional hard spheres.
590 $a School code: 0090.
650 4 $a Biophysics, General. $3 1019105
650 4 $a Engineering, Chemical. $3 1018531
690 $a 0542
690 $a 0786
710 2 $a University of Illinois at Urbana-Champaign. $3 626646
773 0 $t Dissertation Abstracts International $g 68-02B.
790 $a 0090
790 1 0 $a Granick, Steve, $e advisor
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3250356