The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
Aalto

Improving the Biomimetic Properties of Liquid/Liquid Interfaces: Electrochemical and Physicochemical Characterisation

Hélder A. Santos

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Chemical Technology for public examination and debate in Auditorium KE2 at Helsinki University of Technology (Espoo, Finland) on the 28th of September, 2007, at 1 pm.

Overview in PDF format (ISBN 978-951-22-8889-2)   [8276 KB]
Dissertation is also available in print (ISBN 978-951-22-8888-5)

Abstract

This thesis addresses the electrochemical and physicochemical characterisation of the interactions between modified phospholipid monolayers and other model membrane components, polysaccharides and proteins. Also, the assembly of metallic nanoparticles (NPs) on their surface at the polarisable liquid/liquid interfaces is studied. The thesis comprises six original publications and an introductory background to the relevant literature.

In the literature part, relevant background concerning the structure, composition and properties of biological membranes as well as model membranes is briefly reviewed. Classification of gramicidin (gA) ion-channels, glycosaminoglycans (GAGs), in particular dextran sulfate (DS), and glucose oxidase (GOx), with respect to their structure, properties and interaction with lipids is presented. Monolayers at soft interfaces, such as air/liquid and liquid/liquid interfaces, as well as the theory associated with them are also reviewed. Finally, a brief description of the NPs and their characteristics, and isothermal titration calorimetric properties is given.

In the latter part of the thesis, the essential results of the presented publications are summarised and discussed. The thesis introduces an approach to: (i) modify a phospholipid monolayer at a liquid/liquid interface with DS using calcium bridges between DS and the monolayer; (ii) construct polyelectrolyte/gold NP multilayers anchored to a lipid monolayer; (iii) prepare and characterise DS-modified ruthenium NPs, and to study their influence on drug transfer; (iv) study the influence of the peptide gA or enzyme GOx on the lipid layer as well as on the drug permeability; and (v) study the binding mechanism between drug and GAG molecules. Finally, the main conclusions and future perspectives are assessed.

All the studies presented in this thesis involved the combination of ac and dc electrochemical techniques, such as ac impedance/voltammetry and cyclic voltammetry, spectroscopic techniques such as FTIR and fluorescence, and surface (TEM) and calorimetric techniques. Furthermore, the capacitance curves were successfully explained and interpreted with theoretical models, in order to get a closer insight on the ion transfer and membrane interactions for each studied system. It is highlighted that electrochemistry can provide useful information on phenomena taking place at the membrane surface.

This thesis consists of an overview and of the following 6 publications:

  1. Hélder A. Santos, Vladimir García-Morales, Robbert-Jan Roozeman, José A. Manzanares, and Kyösti Kontturi, Interfacial Interaction Between Dextran Sulfate And Lipid Monolayers: An Electrochemical Study, Langmuir 2005, 21, 5475-5484.
  2. Hélder A. Santos, Mariana Chirea, Vladimir García-Morales, Fernando Silva, José A. Manzanares, and Kyösti Kontturi, Electrochemical Study Of Interfacial Composite Nanostructures: Polyelectrolyte/Gold Nanoparticle Multilayers Assembled On Phospholipid/Dextran Sulfate Monolayers At A Liquid–Liquid Interface, The Journal of Physical Chemistry B 2005, 109, 20105-20114.
  3. Hélder A. Santos, Vladimir García-Morales, Lasse Murtomäki, José A. Manzanares, and Kyösti Kontturi, Preparation Of Nanostructures Composed Of Dextran Sulfate/Ruthenium Nanoparticles And Their Interaction With Phospholipid Monolayers At A Liquid–Liquid Interface, Journal of Electroanalytical Chemistry 2007, 599, 194-202.
  4. Hélder A. Santos, Sanna Carlsson, Lasse Murtomäki, and Kyösti Kontturi, Effect Of Gramicidin On Phospholipid-Modified Monolayers And On Ion Transfer At A Liquid–Liquid Interface, ChemPhysChem 2007, 8, 913-920.
  5. Hélder A. Santos, José A. Manzanares, Lasse Murtomäki, and Kyösti Kontturi, Thermodynamic Analysis Of Binding Between Drugs And Glycosaminoglycans By Isothermal Titration Calorimetry And Fluorescence Spectroscopy, European Journal of Pharmaceutical Sciences 2007, in press (doi:10.1016/j.ejps.2007.06.003).
  6. Hélder A. Santos, Elisabete S. Ferreira, Elisa J. Pereira, Carlos. M. Pereira, Kyösti Kontturi, and Fernando Silva, Adsorption–Penetration Studies Of Glucose Oxidase Into Phospholipid Monolayers At 1,2-Dichloroethane/Water Interface, ChemPhysChem 2007, 8, 1540-1547.

Keywords: liquid/liquid interface, phospholipid monolayers, dextran sulfate, capacitance, electrochemistry

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© 2007 Helsinki University of Technology

Last update 2011-05-26