Characterization of solid supported lipoplexes by FTIR microspectroscopy

We investigated, by FTIR microspectroscopy, the interaction of some cationic and helper lipids with DNA deposited on solid supports allowing the formation of ordered structures. FTIR experiments were performed using both conventional and synchrotron radiation infrared sources and by depositing the lipids on both silicon and wedged diamond plates. Cationic liposomes composed of DOTAP (1,2-dioleoyl-3-trimethylammonium–propane) or DDAB (dimethyldioctadecylammonium bromide) and one helper neutral lipid DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) at different cationic lipid/DNA weight ratio, were studied. Spectra of the single components are compared with those obtained for both equimolar cationic–neutral mixture and lipid/DNA complexes.