Production and Characterization of Poly (Lactic Acid)/Nanostructured Carboapatite for 3D Printing of Bioactive Scaffolds for Bone Tissue Engineering.

Biocompatible scaffolds are porous matrices that are bone substitutes with great potential in tissue regeneration. For this, these scaffolds need to have bioactivity and biodegradability. From this perspective, 3D printing presents itself as one of the techniques with the greatest potential for scaffold manufacturing with porosity and established structure, based on 3D digital modeling. Thus, the objective of the present work was to produce 3D scaffolds from the poly (lactic acid) (PLA) and the nanostructured hydroxyapatite doped with carbonate ions (CHA). For this purpose, filaments were produced via fusion for the fused-filament 3D printing and used to produce scaffolds with 50% porosity in the cubic shape and 0/90°configuration. The dispersive energy spectroscopy and Fourier transform infrared spectroscopy (FTIR) analysis demonstrated the presence of CHA in the polymeric matrix, confirming the presence and incorporation into the composite. The thermogravimetric analysis made it possible to determine that the filler concentration incorporated in the matrix was very similar to the proposed percentage, indicating that there were no major losses in the process of obtaining the filaments. It can be assumed that the influence of CHA as a filler presents better mechanical properties up to a certain amount. The biological results point to a great potential for the application of PLA/CHA scaffolds in bone tissue engineering with effective cell adhesion, proliferation, biocompatibility, and no cytotoxicity effects.

Correction to: The use of clays for chlorhexidine controlled release as a new perspective for longer durability of dentin adhesion.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The use of clays for chlorhexidine controlled release as a new perspective for longer durability of dentin adhesion.

The adhesive systems have the function to establish the connection between the restorative material and dental tissue, therefore it is of fundamental importance, because failures in the adhesive interface can reduce the life of a dental restoration. This study investigated the possibility of using the adhesive layer as a chlorhexidine modified release system evaluating their impact on the properties of these systems as well as evaluating the impact of these systems on immediate and post-aging dentin adhesion. Were used a matrix with BisGMA, UDMA, HEMA and TEGDMA copolymer and clay particles (Dellite 67G); associated with a chlorhexidine and a camphorquinone photoinitiator system. The properties of these systems were evaluated by the XRD, FTIR spectrophotometer, flexural strength, elasticity modulus, drug release, enzymatic inhibition and dentin adhesion resistance. The presence of the clay can raise the mechanical properties of the adhesive systems engendering a more resistant hybrid layer and led to a more sustained release of chlorhexidine in the systems, allowing a longer effective period of MMP-2 inhibition. The hypothesis that the addition of clays as release modulators could increase the effectiveness of these drugs in inhibiting the dentin's MPPs and consequently enhancing the adhesive durability was confirmed. These results indicate that the controlled release of chlorhexidine is able to reduce the process of loss of adhesion presenting itself as a promising system to increase the longevity of dental restorations.

Nanoradiopharmaceuticals for breast cancer imaging: development, characterization, and imaging in inducted animals.

Monoclonal antibodies as polymeric nanoparticles are quite interesting and endow this new drug category with many advantages, especially by reducing the number of adverse reactions and, in the case of radiopharmaceuticals, also reducing the amount of radiation (dose) administered to the patient. In this study, a nanoradiopharmaceutical was developed using polylactic acid (PLA)/polyvinyl alcohol (PVA)/montmorillonite (MMT)/trastuzumab nanoparticles labeled with technetium-99m (99mTc) for breast cancer imaging. In order to confirm the nanoparticle formation, atomic force microscopy and dynamic light scattering were performed. Cytotoxicity of the nanoparticle and biodistribution with 99mTc in healthy and inducted animals were also measured. The results from atomic force microscopy showed that the nanoparticles were spherical, with a size range of ~200-500 nm. The dynamic light scattering analysis demonstrated that over 90% of the nanoparticles produced had a size of 287 nm with a zeta potential of -14,6 mV. The cytotoxicity results demonstrated that the nanoparticles were capable of reaching breast cancer cells. The biodistribution data demonstrated that the PLA/PVA/MMT/trastuzumab nanoparticles labeled with 99mTc have great renal clearance and also a high uptake by the lesion, as ~45% of the PLA/PVA/MMT/trastuzumab nanoparticles injected were taken up by the lesion. The data support PLA/PVA/MMT/trastuzumab labeled with 99mTc nanoparticles as nanoradiopharmaceuticals for breast cancer imaging.

Evaluation of the Influence of Modified TiO2 Particles on Polypropylene Composites.

This article reports the preparation of composites and nanocomposites of polypropylene and titanium dioxide particles, with our without surface modification, to obtain photodegradable or photostable materials with less severe environmental impacts. The modification of the titanium dioxide was carried out in the laboratory using propionic acid to improve the interaction of titanium dioxide with the polymer matrix. The composites and nanocomposites were prepared by melt extrusion using a single-screw extruder. The materials obtained were characterized by nuclear magnetic resonance relaxometry, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis and mechanical analysis (tension). The results showed that the surface modification of the titanium dioxide particles promoted their better dispersion, distribution and interaction with the polypropylene matrix, generating a nanocomposite material. The NMR relaxometry results showed that the modified particles changed the molecular dynamics, indicating the formation of nanocomposites. In the Raman spectra, peaks related to the titanium dioxide only appeared at a concentration of 1%, and there was an inversion between crystalline and amorphous phase regions in the samples with the organophilic titanium dioxide, indicating the formation of a nanocomposite. The best modified PP/TiO2 compositions were those containing 0.25 and 0.50% modified TiO2 particles. The incorporation of the titanium dioxide particles, in rutile form, promoted photostabilization of the composites and nanocomposites at all ratios, and the composition containing 0.50% modified TiO2 presented the best photostabilization.

Nanoradiopharmaceuticals for Bone Cancer Metastasis Imaging.

Drug delivery systems are under intense investigation all around the world, especially in oncology research. Indeed, in some cases, like bone metastasis, nanodrugs may represent the last and best choice for both treatment and imaging of early cancer foci. Nuclear medicine has been using MDP labelled with 99mTc as radiopharmaceuticals for many years; however, their use as nanoradiopharmaceuticals is very innovative and creates a new way to establish radiopharmacy in this new scenario offered by nanotechnology. In this study we developed and tested nano-MDP-labelled with 99mTc in rats induced with bone cancer metastasis and the results showed that it may work in patients. However, some further experiments are required in order to initiate protocols in humans.

The effect of the Nb2O5 dispersion on ethylene vinyl acetate to obtain ethylene vinyl acetate/Nb2O5 nanostructured materials.

This work investigated the effect of niobium pentoxide nanoparticles (Nb2O5) on the molecular organization of an ethylene vinyl acetate copolymer (EVA) matrix containing 28% vinyl acetate groups, according to their dispersion and distribution in the polymer matrix. Due to niobium pentoxide's characteristics and properties, it may interfere in the chemical and UV resistance, as well as in the EVA mechanical properties, increasing mechanical resistance. The EVA/Nb2O5 nanocomposite films, with Nb2O5 varying from 0.25 to 1% in relation to the total EVA mass, were prepared by solution casting. The Nb2O5 was well dispersed with the use of ultrasound. These films were mainly characterized by X-ray diffraction and low-field nuclear magnetic resonance through relaxometry, in order to obtain responses on the structural organization and molecular dynamic, respectively, and consequently to understand the effect of the nanoparticles on the EVA matrix. The results showed that the addition of Nb2O5 to the EVA matrix caused changes in its crystallinity and molecular mobility, due to the new interactions formed by the good dispersion of nanoparticles and also their distribution in the EVA matrix, changing the copolymer characteristics due to the formation of a new material.