Effects of manganese incorporation on the morphology, structure and cytotoxicity of spherical bioactive glass nanoparticles

Bioactive glass nanoparticles (BGNPs) are of great interest in tissue engineering as they possess high dissolution rate and capability of being internalized by cells, releasing their dissolution products with therapeutic benefits intracellularly. A modified Stöber process can be applied to obtain different BGNPs compositions containing therapeutic ions while maintaining controllable particle morphology, monodispersity and reduce agglomeration. Here, BGNPs containing Mn, an ion that has been shown to influence the osteoblast proliferation and bone mineralization, were evaluated. Particles with up to 142.3 ± 10.8 nm and spherical morphology were obtained after MnO incorporation in the SiO2 – CaO system. X-ray photoelectron spectroscopy (XPS) indicated the presence of Mn2+ species and also a reduction in the number of bridging oxygen bonds due to the Ca and Mn. The Ca and Mn network modifier role on the silica network was also confirmed by magic-angle spinning 29Si solid-state nuclear magnetic resonance (MAS NMR). MTT evaluation showed no reduction in the mitochondrial metabolic activity of human mesenchymal stem cells exposed to the glass ionic products. Thus, evaluation showed that Mn could be incorporated into BGNPs by the modified Stöber method while maintaining their spherical morphology and features as a promising strategy for tissue regeneration

Effect of severe plastic deformation on the biocompatibility and corrosion rate of pure magnesium

It is well established that magnesium has a considerable potential for use as a biodegradable material. This report describes the effect of processing by severe plastic deformation (SPD) on the grain refinement, mechanical behavior, biocompatibility and corrosion behavior of commercial purity magnesium. The material was received as cast slabs and processed by rolling, equal-channel angular pressing and high-pressure torsion to produce samples with average grain sizes in the range of ~0.5–300 ?m. The results show that severe plastic deformation does not affect the biocompatibility. However, the corrosion behavior is affected by the processing route. Specifically, SPD processing leads to general corrosion as opposed to localized corrosion in the as-cast and hot-rolled condition

Antioxidant, photoprotective and inhibitory activity of tyrosinase in extracts of Dalbergia ecastaphyllum.

Dalbergia ecastaphyllum is a native Brazil plant with importance for beekeeping, and widely used in folk medicine. For the first time, the extracts of this plant were assessed for the presence of hydrophilic and lipophilic antioxidants, as well as inhibition of tyrosinase, free radicals scavenging and sunscreen protection. The antioxidant activity was evaluated by free radical scavenging (DPPH) and β-carotene bleaching assay. The tyrosinase inhibitory activity was evaluated and calculated the EC50. The photoprotective activity was measured using different concentrations of D. ecastaphyllum extracts. The Sun Protection Factor (SPF) of the samples was higher than 6, and the sample from Ilhéus showed the most pronounced photoprotective effect. Sample from Canavieiras presented the highest antioxidant activity by free radical scavenging DPPH and β-carotene bleaching method, with 92.41% and 48.34%, respectively. All samples inhibited the tyrosinase, especially the sample from Prado that was most effective (124.62 μg.mL-1). Significant negative correlation was found between flavonoid contents and inhibition of tyrosinase. The overall results provide relevant information about the Dalbergia ecastaphyllum species, indicating as potential material to cosmetic and pharmaceutical industry