The role of entropic mechanism on the formation of non-cationic lipid and DNA complexes

• Grant number: 11/22394-5
• Support Opportunities: Regular Research Grants
• Start date: March 01, 2012
• End date: May 31, 2014
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Elisabeth Andreoli de Oliveira
• Grantee: Elisabeth Andreoli de Oliveira
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Multilamellar systems formed by regularly spaced bilayers have been used as host phases for colloidal particles or biomolecules opening a wide field of applications in material science and biomedicine, based on manipulation of spatial organization of particles in nanometric scale. The possibility of preparing DNA and non-cationic lipid complexes has been experimentally demonstrated some years ago, and according to a theoretical model, the complexation would be driven by entropic mechanisms related to DNA and bilayers thermal fluctuations. However, this model, cannot properly describe the variety of structures that we have been observed, particularly in the concentrated regime, when DNA fragments are confined between bilayers and thermal fluctuations are inhibited. The objective of this project is experimentally investigating the physical mechanism responsible for stabilization of these complexes, focusing on the role of entropic mechanisms. We will perform structural and dynamical studies on non-cationic lipoplexes, introducing systematic variations on membrane flexibility and also on the dimension of DNA fragments incorporated to the complex, combining X-ray scattering nd microscopy (polarization and fluorescence) experiments. (AU)