Influencia del contenido de OHAP y de gentamicina en la liberación del antibiótico a partir de composites de OHAP/PEMMA

El objetivo de este trabajo fue estudiar la influencia del contenido de hidroxiapatita (OHAp) y de sulfato de gentamicina (SG) en la velocidad de liberación de dicho antibiótico a partir de materiales compuestos por OHAp, polimetacrilato de metilo (PMMA) y polimetacrilato de etilo (PEMA). Para ello se prepararon muestras con diferente proporción de OHAp (30 y 40%) y de SG (5 y 10%). El estudio de liberación se llevó a cabo sumergiendo 3 muestras de cada grupo en SBF a 37°C, el medio fue renovado a diferentes intervalos de tiempo durante 70 días. La concentración de gentamicina fue determinada por el método del o-ftaldialdehído. Los resultados del estudio de liberación mostraron, que la liberación ocurre de manera más rápida durante las primeras 10 horas de inmersión en SBF y que posteriormente se hace más lenta. Se observó que las muestras con un mayor tanto por ciento (40%) de OHAp liberan mayor cantidad de antibiótico. Las muestras con un 40% de OHAp liberaron el 100% de SG a los 70 días, mientras que en ese mismo período las muestras con 30% de OHAp liberaron un 85%. Por otra parte, se observó que la cantidad de gentamicina añadida inicialmente no afecta el tanto por ciento de SG que se libera.Peer Reviewe

Achievements in Mesoporous Bioactive Glasses for Biomedical Applications

Nowadays, mesoporous bioactive glasses (MBGs) are envisaged as promising candidates in the field of bioceramics for bone tissue regeneration. This is ascribed to their singular chemical composition, structural and textural properties and easy-to-functionalize surface, giving rise to accelerated bioactive responses and capacity for local drug delivery. Since their discovery at the beginning of the 21st century, pioneering research efforts focused on the design and fabrication of MBGs with optimal compositional, textural and structural properties to elicit superior bioactive behavior. The current trends conceive MBGs as multitherapy systems for the treatment of bone-related pathologies, emphasizing the need of fine-tuning surface functionalization. Herein, we focus on the recent developments in MBGs for biomedical applications. First, the role of MBGs in the design and fabrication of three-dimensional scaffolds that fulfil the highly demanding requirements for bone tissue engineering is outlined. The different approaches for developing multifunctional MBGs are overviewed, including the incorporation of therapeutic ions in the glass composition and the surface functionalization with zwitterionic moieties to prevent bacterial adhesion. The bourgeoning scientific literature on MBGs as local delivery systems of diverse therapeutic cargoes (osteogenic/antiosteoporotic, angiogenic, antibacterial, anti-inflammatory and antitumor agents) is addressed. Finally, the current challenges and future directions for the clinical translation of MBGs are discussed

Rod-like mesoporous silica nanoparticles with rough surfaces for enhanced cellular delivery

Novel rod-like mesoporous silica nanoparticles with a rough surface have been prepared with 37% higher cellular uptake and drug delivery efficacy compared to their counterparts with a smooth surface

Oxygen diffusion in nanostructured perovskites

Nonstoichiometric perovskite-related oxides (such as ferrites and cobaltites, etc.) are characterized by fast oxygen transport at ambient temperatures, which relates to the microstructural texturing of these materials, consisting wholly of nanoscale microdomains. We have developed an inhomogeneous diffusion model to describe the kinetics of oxygen incorporation into nanostructured oxides. Nanodomain boundaries are assumed to be the high diffusivity paths for oxygen transport whereas diffusion into the domains proceeds much slower. Using Laplace transform methods, an exact solution is found for a ramped stepwise potential, allowing fitting of the experimental data to theoretical curves (in Laplace transforms). A further model generalization is considered by introducing additional parameters for the size distribution of domains and particles. The model has been applied for qualitative evaluation of oxygen diffusion parameters from the data on wet electrochemical oxidation of nano-structured perovskite SrCo_0.5Fe_0.2Ta_0.3O_{3-y} samples.Comment: Submitted for ICCMR-7 conference (Italy). Latex (elsart.cls), 15 pages, 7 figure