Influência de polímeros sínteticos sobre coloides de sílica: estabilidade coloidal e interações da nano-bio interface

Abstract

To obtain stable colloidal systems in biocompatible dispersants is essential for nanoparticles biomedical application. The interaction of these materials with the biological medium is influenced by their composition, surface, shape and colloidal characteristics. When macromolecules, such as synthetic polymers, are added in the medium, they may promote nanoparticles colloidal stability in dispersants with high ionic strength (i.e. Phosphate Buffer). However, little is known about the influence of these molecules on the interactions between nanomaterials and organism’s biological components, such as proteins and cells, which are present where the colloids will be applied. In this work, it was shown that the addition of the polymers (i) PF127, (ii) PEG with different molecular weights – 1500 Da, 12000 Da and 35000 Da – and (iii) the protein bovine serum albumin (BSA), on colloids of silica nanoparticles dispersed in PBS affect on their colloidal stability through different mechanisms. All molecules adsorbed on the material surface, however, while BSA maintained the SiNPs dispersed in the medium by electrosteric stabilization mechanisms, the polymers PEG and PF127 leaded the occurrence of depletive forces between the particles. Therefore, it was found that interactions between polymers and nanoparticles are reversible and the material surface remains accessible to proteins when it is incubated in human blood plasma, even with high concentrations of polymers in the medium. On the other hand, BSA had a greater effect on the SiNPs Protein Corona profile than polymers, when it was added in concentrations over 5% on nanoparticles suspensions. The studies of Protein Corona allowed to evaluate the effects that the polymers and the BSA have on the protein adsorption on SiNPs surfaces and complemented the studies about the interactions between the stabilizing molecules with the nanoparticles surface.