EMU granted in the process 2013 / 14262-7 thematic project - DLS

Abstract

The use of phospholipid vesicles, in addition to the Langmuir films, is a widely used strategy in the area of biological membrane mimetic systems for studies of the interaction of analytes of interest such as pesticides, drugs and nanoparticles, with such mimetic systems. This is one of the objectives of this project and in this context, it is necessary to control some physical parameters of vesicles, such as size and surface charge, which will be obtained via dynamic light scattering (DLS) and zeta potential, respectively. The surface charge of the vesicle is a preponderant factor in the analyte-vesicle interaction, facilitating, or not, the adsorption of the analyte on the surface of the vesicle, and consequently the interaction between them. The analyte-vesicle interaction, when it occurs and depending on the intensity with which it occurs, affects the dimensions of the vesicle, and may even prevent the formation of vesicles or destroy them after formation. The size and surface charge control is also necessary in the case of the application of metallic nanoparticles involving the surface-enhanced Raman scattering (SERS) phenomenon for the detection of the analytes of interest mentioned above. This is the other goal of this project. The metal nanoparticles, mainly Au and Ag, are synthesized in our laboratories. The size of the nanoparticles is a determinant factor in the amplification factor of the Raman signal, generating the signal SERS, even more considering that we work in very diluted concentrations (traces), tending to the regime of single molecule (single molecule). The surface charge of the nanoparticles is another determinant of Raman signal amplification, since the ideal case of maximum amplification requires the adsorption of the analyte of interest on the surface of the metallic nanoparticles, so that the equilibrium of charges between nanoparticles and analytes is a Factor in this issue. (AU)