Electrostatically self-assembled nanoparticles based on biomolecules [Elektronische Ressource] / vorgelegt von Li Yi

Liyi

Informations

• Publié par: johannes_gutenberg-universitat_mainz
• Publié le: 01 janvier 2009
• Nombre de lectures: 5
• Langue: English
• Poids de l'ouvrage: 4 Mo

Extrait

Electrostatically Self-Assembled
Nanoparticles Based on Biomolecules




DISSERTATION

Zur Erlangung des Grades
“Doktor der Naturwissenschaften”

am Fachbereich Chemie, Pharmazie und Geowissenschaften
der Johannes Gutenberg-Universität Mainz




vorgelegt von

M.Sc. Li Yi

Born in Nanjing, P. R. China




Mainz, 2009


Content


Chapter 1. Introduction and Motivation ......................................... 1

Chapter 2. Background................................................................... 5
2.1 Association of DNA with Counterions...........................................5
2.2 Association of Oligolysine/Polylysine with DNA..........................8
2.3 Diffusion Behavior of Polyelectrolytes ........................................10

Chapter 3. Characterization Methods........................................... 12
3.1 Light Scattering.............................................................................12
3.1.1 Static Light Scattering............................................................................13
3.1.2 Dynamic Light Scattering ......................................................................17
3.2 Atomic Force Microscopy ............................................................21
3.3 Gel Electrophoresis .......................................................................25
3.4 Zeta Potential ................................................................................27

Chapter 4. Association of DNA with Organic Counterions ......... 29
4.1 Introduction...................................................................................29
4.2 Characterization of DNA ..............................................................31
4.3 Association of DNA with Divalent Counterions ..........................44
4.4 Tetravalent Counterions......................63
4+4.4.1 Association of DNA with C6T .............................................................63
4.4.2 Association of DNA with PSPDI............................................................69
4.5 Conclusions...................................................................................88

Chapter 5. Association of Sodium Polystyrene Sulfonate with
Oligolysines……… ...................................................................... 91
1
5.1 Introduction...................................................................................91
5.2 Characterization of the Components.............................................93
5.3 Association of NaPSS with Trilysine ...........................................97
5.4 Association of NaPSS with Different Oligolysines....................118
5.4.1 Association of NaPSS with Dilysine ................................................... 118
5.4.2 Association of NaPSS with Tetralysine............................................... 119
5.4.3 Association of NaPSS with Pentalysine .............................................. 121
5.5 Conclusions.................................................................................126

Chapter 6. Polyelectrolyte Assemblies in AFM ......................... 128
6.1 Introduction128
6.2 Influence of Surface Charge .......................................................130
6.3 Influence of Preparation Method ................................................135
6.4 Influence of Added Salt ..............................................................136
6.5 Conclusion...................................................................................138

Chapter 7. Summary................................................................... 140

Chapter 8. Experimental Section................................................ 145

List of Abbreviations .................................................................. 151

References and Notes ................................................................. 153



2 Chapter 1. Introduction and Motivation
Chapter 1. Introduction and
Motivation


Self-assembly is driven by nonconvalent interactions and the association of
1,2,3,4subunits leads to supramolecular oligomers, aggregates or materials.
Compared to synthetic macromolecules which contain covalent bonds, the
5aggregates formed by self-assembly exhibit two major advantages: (1) it is much
simpler to produce supramolecular structures and adjust physical, chemical
and/or biological properties. (2) The noncovalent interactions in the assembly
give the possibility of rearrangement of the components upon external stimuli,
which may lead to further applications of the assemblies. The bilayer structure of
the cell membrane and the double helix structure of the DNA are perfect
examples of supramolecular structures formed by self-assembly in nature.
Thereby, inspired from that, it has attracted tremendous attention and interest to
fundamentally understand and practically design self-assembled nanoparticles
and supramolecular structures.

The noncovalent interactions in the self-assembly can involve hydrophobic
interaction, hydrogen bonding, metal coordination, electrostatic interaction or a
combination of these. The hydrogen bond represents a bridge between a
hydrogen atom which is covalently bound to an electronegative atom like oxygen
or fluorine and an electronegative atom with at least one lone pair of electrons.
The “hydrophobic effect” causes the formation of clusters of hydrophobic or
amphiphilic molecules in aqueous solution. It releases water molecules from the
hydrophobic molecule surfaces into the bulk solvent. This yields an entropy gain,
which is the origin of the hydrophobic interaction in water. The electrostatic
interaction is raised from the force between two charged molecules (either
1 Chapter 1. Introduction and Motivation
repulsive or attractive), which is also known as Coulomb force. While the
6,7hydrophobic effect is the origin for the formation of classical micelles and the
8, 9,10,11,12assembly of many other amphiphilic molecules, also hydrogen bonding
13,14,15and metal coordination lead to supramolecular materials. Assemblies and
materials with supramolecular architectures based on the mentioned interaction
forces can combine certain properties of two different components or exhibit
special properties and thus open the possibility for numerous applications that
cannot be achieved by the individual components. The formation of
supramolecular structures through self-assembly can be either kinetically or
16,17thermodynamically controlled. In a kinetically controlled aggregate, a frozen
irreversible structure is obtained and usually dependents on the way of
preparation. For the complexes formed thermodynamically, the resulting
structure is in thermodynamic equilibrium due to the possible rearrangement of
the building blocks. While it is of fundamental interest how the structure found is
controlled, both structural types may be of interest for certain properties and
functions.

Polyelectrolytes represent a promising candidate for self-assembly because they
exhibit both polymeric and electrolytic properties. A self-assembly process
involving polyelectrolytes is normally based on electrostatic interaction due to the
existence of charges when dissolving polyelectrolyte in the solution. The
assembly of polyelectrolytes with oppositely charged components is also
18,19,20,21,22,23,24specified as “electrostatic self-assembly”. Various building blocks
have been combined with polyelectrolytes: oppositely charged polyelectrolytes,
metal ions, surfactants or small organic counterions with certain geometry. In the
polyelectrolyte-polyelectrolyte complexes, resulting structures can be described
predominately by one of two models: the ladderlike structure or the scrambled
25egg structure. These however usually represent aggregates with a broad size
distribution and little structural control. Depending on composition and
concentration, also precipitation occurs. A way to organize polyelectrolyte-
polyelectrolyte systems is the layer-by-layer deposition, yielding films, capsules
2 Chapter 1. Introduction and Motivation
26,27,28or solid materials. A similar scenario as for inter-polyelectrolye complexes
exists when combing polyelectrolytes with multivalent metal counterions. Due to
the large conformational freedom of the polyelectrolyte and the small
unstructured counterion, aggregates usually do not exhibit a certain structure. At
29,30,31,32some amount of multivalent counterions, complexes also precipitate. In
contrast, polyelectrolyte-surfactant complexes usually generate solid structured
materials. The assembly structure is more defined and versatile than that of
polyelectrolyte-polyelectrolyte complexes mainly due to the secondary
hydrophobic interaction in-between surfactant tails, which can direct the
33,34association into more ordered nanostructures. However, neither of the above
states can yield aggregates with well-defined supramolecular structures that are
stable in solution. A recent branch of self-assembled polyelectrolyte sy