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