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Scientific Report 2007-2009<br />
Condensed matter physics and biophysics<br />
C26. Biomolecules-lipid membranes interaction study : A<br />
contribution to gene therapy and drug delivery<br />
Solid-supported lipid-films are considered as an attractive<br />
and useful model system for biological membranes<br />
and have been extensively studied as a peculiar class of<br />
materials due to their potential applications in various<br />
fields. In particular, amphipathic lipid films on solid<br />
support allow the study of structural investigation of<br />
important biological model systems such as the vector<br />
like lipid membranes, in order to improve DNA transfection<br />
in non viral gene therapy and as a template for<br />
nanostructure construction. In fact polyanionic DNA<br />
binds to cationic lipids to form electrostatic complexes,<br />
exhibiting, due to the amphipathic lipid structure, rich<br />
self-assembled ordered structures with different delivery<br />
efficiency through membrane cells. Moreover, the transfection<br />
efficiency of lipid-DNA complexes into cells can<br />
be increased by means of the inclusion of a neutral lipid<br />
which helps the cationic one in forming and maintaining<br />
lipid-DNA linkage. Selfassembled crystal-liquid phases<br />
of cationic and neutral amphipathic lipid molecules are<br />
very sensitive to the chemophysical properties present<br />
at the interface between the systemand the surrounding<br />
environment, such as theair temperature and relative humidity.<br />
By means of the use of flat semiconductor interface<br />
as solid substrate, to obtain an airbiofilm- slide system,<br />
which maintains the structural characteristic of the<br />
liposome aggregation, we are able to monitor the biofilm<br />
stereochemical arrangement controlling both temperature<br />
and relative humidity parameters of the air interface.<br />
We found [1-2] that the mixture of cationic/neutral<br />
lipid system which was deposited on silicon wafer by spin<br />
coating, was ordered as multiple bilayers with the presence<br />
of micron-sized clusters; DNA strand can influence<br />
such cluster formation without managing to organize itself<br />
within the mixture. Recently, by means of neutron<br />
reflectivity at the CRISP reflectometer at ISIS pulsed<br />
neutron source facility, we enlighten the lyotropic behaviour<br />
of silicon supported neutral lipid DOPC and<br />
cationic lipid DDAB with respect to the property shown<br />
by their mutual interaction under saturated deuterium<br />
oxide vapour, pointing out that the lipid mixture is organized<br />
in ordered domains composed of plane lamellar<br />
bilayers of non interactive DOPC and DDAB. Such<br />
biphasic arrangement weakens the helper role of DOPC<br />
thus favouring the DNA-lipid complex formation.<br />
Other measurements we performed by in house X-ray<br />
diffractometer [3] devoted to stress the influence of<br />
the temperature on the lipid cluster formation in the<br />
mixture DOPC-DDAB, showed that at temperature<br />
higher with respect to the crystal gel-crystal liquid<br />
phase transition temperature of the DDAB, the mixture<br />
dissolves the biphasic structure on behalf of a<br />
single thermolyotropic mesophase. Furthermore DNA<br />
presence in the biphasic lipid structure lowers the<br />
temperature of the cluster dissolution and at 37 ◦ C is<br />
able to form single ordered structure.<br />
Figure 1: Peptide pore in lipid membrane.<br />
Our research is now focused on other mechanisms able<br />
to delivery drugs, proteins, plasmid and genes into<br />
viable cells (tumoral or not). Recent studies show that<br />
the ultrasound can be used to deliver biomolecules into<br />
the cells offering attractive opportunities as non-invasive<br />
efficient therapy. By using a coordinate combination<br />
of FTIR Spectroscopy, Microscopy, EPR and Flow<br />
Cytometry techniques, we have analyzed the cellular<br />
processes (such as apoptosis and membrane poration)<br />
induced by different external agents [4].<br />
References<br />
1. F. Domenici, et al, Appl. Phys. Lett. 92, 193901 (2008)<br />
2. J. Generosi, et al, Journal of Microscopy 229, 259 (2008)<br />
3. F. Domenici F., et al, Colloids Surf., B 69, 216 (2009)<br />
4. L. Di Giambattista et al., Eur. Biophys. J. 39, 929<br />
(2009).<br />
Authors<br />
A. Congiu Castellano, S. Belardinelli, L. Di Giambattista,<br />
F. Domenici, J. Generosi, P. Grimaldi<br />
http://phys.uniroma1.it/gr/MOC-BIO/index.htm<br />
<strong>Sapienza</strong> Università di Roma 79 Dipartimento di Fisica