Estudo das interações laponita-polifosfato para obtenção de coacervados

Abstract

The development of biomaterials with biological and structural properties for applicability in Tissue Engineering and Regenerative Medicine (TERM) is challenged by the presence of biocompatible components in their matrix, presence of shear-thinning characteristics and being able to maintain their structural integrity when inserted in a physiological microenvironment. The present research aims to explore the synthesis of new materials involving the LRD-polyP (Laponite-polyphosphate) system, in order to develop coacervates that can be used in future applications in regenerative medicine. The addition of divalent cations and methanol to the LRD-polyP clusters were explored in order to promote the coacervation of the system. Using dielectric relaxation spectroscopy, electrical properties directly related to the molecular structure of all materials under study were evaluated. Regarding the LRD-polyP-Ca2+ systems, the samples were characterized using other analyzes such as Fourier Transform Infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA) and rheology. The results obtained through visual observations showed that that polyP solutions in the presence of Ca2+ form a dense and viscous precipitate, called coacervates. The LRD-polyP clusters in the presence of calcium ions underwent liquid-liquid phase separation, with precipitation of white flocculates. The concentration ratio [P]/[Ca2+] was a determining factor in the formation of weak and coacervated gels. As for the presence of methanol, the formation of a weak gel with a cloudy appearance was observed. Through thermogravimetric analysis, it was possible to observe that the samples present an excellent thermal stability, being resistant to high temperatures. The rheological analysis revealed that the materials showed shear-thinning properties and that the increase in the concentration of Ca2+ and Laponite brought improvements to the mechanical properties of these materials. Through the analysis of dielectric relaxation spectroscopy, it was possible to verify improvements in the conduction paths and in the conductivity of the materials. For LRD-polyP-Ca2+ samples, the conductivity exhibited an increase as Ca2+ concentrations increased and remained practically unchanged with increasing Laponite and polyphosphate concentrations. The dielectric relaxation of the permittivity for the samples in which there was an increase in Ca2+ changed to higher frequencies, indicating a greater dynamic of the charge carrier protons. Regarding the LRD-polyP system in the presence of methanol, there was a decrease in the dielectric constant of the solution as the methanol concentration increased, implying a decrease in ionic conductivity and revealing the dehydration effect of the system. Biomaterials for tissue regeneration must have good ionic conduction properties, present biocompatible components, mechanical and structural strength, and be able to maintain their structural integrity after being injected into a physiological medium. Systems based on LRD-polyP interactions in the presence of calcium showed intrinsic characteristics of injectable biomaterials, making them promising for applications in tissue engineering.