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.

Nanostructured fumarate copolymer-chitosan crosslinked scaffold: An in vitro osteochondrogenesis regeneration study

In the tissue engineering field, the design of the scaffold inspired on the natural occurring tissue is of vital importance. Ideally, the scaffold surface must promote cell growth and differentiation, while promote angiogenesis in the in vivo implant of the scaffold. On the other hand, the material selection must be biocompatible and the degradation times should meet tissue reparation times. In the present work, we developed a nanofibrous scaffold based on chitosan crosslinked with diisopropylfumarate-vinyl acetate copolymer using anodized aluminum oxide (AAO) templates. We have previously demonstrated its biocompatibility properties with low cytotoxicity and proper degradation times. Now, we extended our studies to demonstrate that it can be successfully nanostructured using the AAO templates methodology, obtaining a nanorod-like scaffold with a diameter comparable to those of collagen fibers of the bone matrix (170 and 300 nm). The nanorods obtained presented a very homogeneous pattern in diameter and length, and supports cell attachment and growth. We also found that both osteoblastic and chondroblastic matrix production were promoted on bone marrow progenitor cells and primary condrocytes growing on the scaffolds, respectively. In addition, the nanostructured scaffold presented no cytotoxicity as it was evaluated using a model of macrophages on culture. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 570-579, 2018.

Effect of the curing conditions on the properties of an acrylic denture base resin microwave-polymerised

OBJECTIVES

The aim of this study is to evaluate the effect of the different conditions of curing on the residual monomer levels, hardness and impact strength of a microwave-polymerised acrylic resin.

METHODS

The material was polymerised in a microwave oven in four different conditions of power and curing time. The kinetics of release of residual monomer in water was evaluated by spectrophotometric method up to 24 h. The hardness of the sample was determined by the Rockwell method and the impact strength tested by the Charpy method. The results were subjected to statistical analysis using ANOVA and Tukey's test for comparison.

RESULTS

The levels of residual monomer were found dependent upon the curing conditions and they were correlated with the values of impact strength. Significant differences were observed in this property regarding the analysed conditions (p<0.001).

CONCLUSIONS

From the appropriate selection of power and time of curing of the resin, it is possible to optimise the level of residual monomer and a low cytotoxicity keeping at the same time the best mechanical properties.

A vanadium/aspirin complex controlled release using a poly(beta-propiolactone) film. Effects on osteosarcoma cells

A delivery system for vanadium was developed using poly(beta-propiolactone) (PbetaPL) films. The release kinetics of a complex of vanadium (IV) with aspirin (VOAspi) was evaluated with films prepared from polymers of different molecular weights, as well as with variable drug load. A sustained release of vanadium over 7 days was achieved. The drug release kinetics depends on contributions from two factors: (a) diffusion of the drug; and (b) erosion of the PbetaPL film. The experimental data at an early stage of release were fitted with a diffusion model, which allowed determination of the diffusion coefficient of the drug. VOAspi does not show strong interaction with the polymer, as demonstrated by the low apparent partition coefficient (approximately 10(-2)). UMR106 osteosarcoma cells were used as a model to evaluate the anticarcinogenic effects of the VOAspi released from the PbetaPPL film. VOAspi-PbetaPL film inhibited cell proliferation in a dose-response manner and induced formation of approximately half of the thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation. compared to that with free VOAspi in solution. The unloaded PbetaPL film did not generate cytotoxicity, as evaluated by cell growth and TBARS. Thus, the polymer-embedded VOAspi retained the antiproliferative effects showing lower cytotoxicity than the free drug. Results with VOAspi-PbetaPL films suggest that this delivery system may have promising biomedical and therapeutic applications.