Fumarate copolymers-based membranes overlooking future transdermal delivery devices: synthesis and properties

Terpolymer-chitosan membranes as biomaterial

The present study shows a novel copolymer synthesis, its application in the membrane design and the physicochemical and biological characterization of the biomaterial obtained. Terpolymer starting diisopropyl fumarate (F), vinyl benzoate (V) and 2-hydroxyethyl methacrylate (H) was prepared by thermal radical polymerization. This polymer (FVH) was obtained in several monomer ratios and characterized by spectroscopic and chromatographic methods (FTIR, ¹ H-NMR and SEC). The best relationship of F:V:H was 5:4:1, which allows efficient interaction with chitosan through cross-linking with borax to achieve scaffolds for potential biomedical applications. The membranes were obtained by solvent casting and analyzed by scanning electron microscopy (SEM), swelling behavior and mechanical properties. In addition, we studied the possible cytotoxicity and biocompatibility of these materials using a murine macrophage-like cell line (RAW 264.7) and bone marrow mesenchymal progenitor cells (BMPC), respectively, taking into account their intended applications. The results of this study show that the terpolymer obtained and its combination with a natural polymer is a very interesting strategy to obtain a biomaterial with possible applications in regenerative medicine and this could be extended to other structurally related systems.

Nanobiocomposite based on natural polyelectrolytes for bone regeneration

We developed a composite hydrogel based on chitosan and carboxymethyl cellulose with nanometric hydroxyapatite (nHA) as filler (ranging from 0.5 to 5%), by ultrasonic methodology to be used for bone regeneration. The 3D porous-structure of the biocomposite scaffolds were confirmed by Scanning Electron Microscopy and Microtomography analysis. Infrared analysis did not show specific interactions between the organic components of the composite and nHA in the scaffold. The hydrogel properties of the matrices were studied by swelling and mechanical tests, indicating that the scaffold presented a good mechanical behavior. The degradation test demonstrated that the material is slowly degraded, while the addition of nHA slightly influences the degradation of the scaffolds. Biocompatibility studies carried out with bone marrow mesenchymal progenitor cells (BMPC) showed that cell proliferation and alkaline phosphatase activity were increased depending on the matrix nHA content. On the other hand, no cytotoxic effect was observed when RAW264.7 cells were seeded on the scaffolds. Altogether, our results allow us to conclude that these nanobiocomposites are promising candidates to induce bone tissue regeneration.

Ultrasonic compatibilization of polyelectrolyte complex based on polysaccharides for biomedical applications

In recent years, there has been an increasing interest in the design of biomaterials for cartilage tissue engineering. This type of materials must meet several requirements. In this study, we apply ultrasound to prepare a compatibilized blend of polyelectrolyte complexes (PEC) based on carboxymethyl cellulose (CMC) and chitosan (CHI), in order to improve stability and mechanical properties through the inter-polymer macroradicals coupling produced by sonochemical reaction. We study the kinetic of the sonochemical degradation of each component in order to optimize the experimental conditions for PEC compatibilization. Scaffolds obtained applying this methodology and scaffolds without ultrasound processing were prepared and their morphology (by scanning electron microscopy), polyelectrolyte interactions (by FTIR), stability and mechanical properties were analyzed. The swelling kinetics was studied and interpreted based on the structural differences between the two kinds of scaffolds. In addition we evaluate the possible in vitro cytotoxicity of the scaffolds using macrophage cells in culture. Our results demonstrate that the ultrasound is a very efficient methodology to compatibilize PEC, exhibiting improved properties compared with the simple mixture of the two polysaccharides. The test with murine macrophage RAW 264.7 cells showed no evince of cytotoxicity, suggesting that PEC biomaterials obtained under ultrasound conditions could be useful in the cartilage tissue engineering field.