SOFT MATERIALS BASED ON VESICLES AND BIOPOLYMERS

Vesicles are hollow spherical structures formed by the self-assembly of amphiphilic molecules in aqueous solution. They are of great interest for applications ranging from drug delivery and controlled release to separations and sensing. However, the limited stability of vesicles to external conditions such as pH, temperature or ionic strength has hampered their applicability. In this dissertation, we explore the integration of vesicles with biopolymers as a route to creating vesicle-bearing soft materials with increased stability. Two specific types of such materials are studied: (a) vesicle gels, where the vesicles are linked into a network by biopolymer chains; and (b) vesicle-loaded capsules, where the vesicles…

Contents

1. Introduction and Overview
1.1. Problem Description and Motivation
1.2. Proposed Approach
1.2.1 Vesicle Gels Anchored by Biopolymers
1.2.2 Vesicles Loaded into Biopolymer Capsules
1.3. Significance of this Work
2. Background
2.1. Vesicles and Liposomes
2.1.1 Vesicle Preparation from Lipids
2.2. Associating Polymers
2.3. Biopolymers
2.3.1 Chitosan
2.3.2 Chitosan Modification
2.4. Characterization Techniques
2.4.1 Rheology
2.4.2 Small-Angle Neutron Scattering (SANS)
2.4.3 Dynamic Light Scattering (DLS)
2.4.4 Cryo-Transmission Electron Microscopy (Cryo-TEM)
3. Vesicle Gels Anchored by an Associating Biopolymer
3.1. Introduction
3.1.1 Associating Polymer-Vesicle Mixtures: Previous Work
3.2. Materials and Methods
3.2.1. SANS Modeling of Vesicles
3.3. Results
3.3.1 Phase Behavior and Rheology
3.3.2 SANS
3.4. Discussion
3.5. Conclusions
4. Vesicle Morphology Changes Induced by an Associating Biopolymer
4.1. Introduction
4.1.1 SANS Modeling of Lamellar Phases: Previous Work
4.1.2. Polymer Effects on Lamellar Phases: Previous Work
4.2. Materials and Methods
4.3. Results and Discussion
4.3.1 SANS Data and Modeling
4.3.2 Cryo-TEM Data
4.3.3 Analysis of Parameters from SANS Modeling
4.3.4 Mechanism for Structural Transitions
4.3.5 Stability of Vesicle Co-Existence: Aging Effects
4.5. Conclusions
5. Vesicle-Biopolymer Capsules and Gels: Controlled Release Studies
5.1. Introduction
5.1.1 Drug Delivery from Vesicle Gels: Previous Work
5.1.2 Drug Delivery from Vesicle-Loaded Capsules: Previous Work
5.2. Materials and Methods
5.3. Results
5.3.1 Vesicle Gel Formation Using Lipid Vesicles
5.3.2 Dye Release from Vesicle Gels
5.3.3 Preparation of Capsules Loaded with Vesicles
5.3.4 Preparation of Magnetic Capsules
5.3.5 Conjugation of Antibodies to the Capsules
5.3.6 Dye Release from Vesicle-Loaded Capsules
5.4. Conclusions
6. Conclusions and Recommendations
6.1. Conclusions
6.2. Recommendations for Future Work
References

Author: Lee, Jae-Ho

Source: University of Maryland

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