X-ray scattering techniques applied to the study of biomaterials at the air/liquid interface

GASPERINI-MALFATTI, ANTONIO; PUENTES-MARTINEZ XIMENA; RAFAEL GUSTAVO OLIVEIRA; PUSTERLA JULIO MARTÍN; SOARES MÁRCIO; CAVALCANTI, LEIDE PASOS

Campinas

Congreso; XV Brazil Material Research Society Meeting; 2016

Brazilian Material Research Society

Thin and ultrathin films in liquid surfaces and interfaces represent a model case to study the dynamical, electronic and structural properties of two-dimensional confined soft matter. Among them, a very interesting class of ultrathin films is given by the Langmuir monolayers, which are monomolecular layers of amphiphilic molecules spread on air/water interface. Langmuir monolayers of amphiphilic lipids constitute a convenient experimental system to model biomembranes. A big variety of physical parameters can be easily and precisely determined on these films, such as surface pressure, molecular area, surface potential and others. Moreover, the effect of the interaction between the film and the subphase or subphase components (pH, ions and/or other molecules) can also be studied. Surface-sensitive synchrotron-based X-ray scattering techniques such as grazing-incidence diffraction (GID) and scattering (GISAXS/GIXOS) are powerful tools for investigating the molecular structure of liquid surfaces mainly due to the penetrating properties of the X-rays, optimized for the thickness of these films. In this work we present some results obtained using the new instrumentation for performing surface-sensitive X-ray scattering techniques at air/liquid interfaces located at LNLS/XRD2 beamline. We used this setup to study Langmuir monolayers formed by natural and/or synthetic lipids to follow the changes on monolayers? structure with the introduction of a natural antibiotic molecule into the subphase. This instrumentation opens new possibilities for the Brazilian soft condensed matter community, since the tunability of structure with the change of preparation conditions and thermodynamical parameters make these systems ideal candidates for many technological and industrial applications.