This report describes the effects of deoxyribormcleic acid (DNA) on the interfacial properties of an active lipidic matrix designed for polynucleotide immobilization. The synthetic lipid DiOctadecylamidoGlycylSpennine (DOGS) was spread at the air-water interface to form a functionalized film capable of capturing DNA molecules present in the subphase, as confirmed by Attenuated Total Reflection-Fourier Transform InfraRed spectroscopy. The predominance of electrostatic interactions in the DNA adsorption process onto the DOGS monolayer was demonstrated by changing the subphase ionic strength. In the presence of various DNA concentrations in the subphase and with increasing incubation times the compression isotherms of the DOGS monolayer were progressively modified, which suggested a change in monolayer fluidity. This finding was corroborated by the direct observation of the mixed monolayer morphology by Brewster Angle Microscopy. Taken together, these results suggest a reorganization of lipids at the interface following DNA adsorption. (c) 2005 Elsevier B.V. All rights reserved.