Kinetic studies of the release profiles of antiepileptic drug released from a nanostructured TiO2 matrix.

In this paper is reported the “in vitro†release kinetic studies of antiepileptic drugs released from an inorganic, titanium oxide (TiO2) porous matrix. In order to determine the drug release mechanism, the experimental values were fitted to different mathematical models: zero-order, firs-order, Higuchi, Hixson-Crowel and Peppas. TiO2 was prepared by the sol-gel method adding valproic acid (VPA) or phenytoine (DHP) during the titanium n-butoxide hydrolysis step. The drug-TiO2 systems were observed by scanning electron microscopy. The “in vitro†release experiments were performed at laboratory scale following the United States Pharmacopeia (USP) standards. The obtained materials have a morphology of nanoparticle agglomerates. The particles have different sizes with some roughness and spherical shape. Peppas model suggests for both systems, that the release mechanism is controlled by two parallel processes. The first one is by diffusion of the drug through the matrix and the second is related to a gradient of constant diffusion by ingress of the solvent in the matrix

Bismuth oxide aqueous colloidal nanoparticles inhibit Candida albicans growth and biofilm formation

Abstract: Multiresistance among microorganisms to common antimicrobials has become one of the most significant concerns in modern medicine. Nanomaterials are a new alternative to successfully treat the multiresistant microorganisms. Nanostructured materials are used in many fields, including biological sciences and medicine. Recently, it was demonstrated that the bactericidal activity of zero-valent bismuth colloidal nanoparticles inhibited the growth of Streptococcus mutans; however the antimycotic potential of bismuth nanostructured derivatives has not yet been studied. The main objective of this investigation was to analyze the fungicidal activity of bismuth oxide nanoparticles against Candida albicans, and their antibiofilm capabilities. Our results showed that aqueous colloidal bismuth oxide nanoparticles displayed antimicrobial activity against C. albicans growth (reducing colony size by 85%) and a complete inhibition of biofilm formation. These results are better than those obtained with chlorhexidine, nystatin, and terbinafine, the most effective oral antiseptic and commercial antifungal agents. In this work, we also compared the antimycotic activities of bulk bismuth oxide and bismuth nitrate, the precursor metallic salt. These results suggest that bismuth oxide colloidal nanoparticles could be a very interesting candidate as a fungicidal agent to be incorporated into an oral antiseptic. Additionally, we determined the minimum inhibitory concentration for the synthesized aqueous colloidal Bi2 O3 nanoparticles

Production of Methanol from Aqueous CO2 by Using Co3O4 Nanostructures as Photocatalysts

In this work, we report for the first time the photocatalytic activity of Co3O4 nanostructures for the reduction of aqueous CO2 to methanol (MeOH). This could be considered a simple example of artificial photosynthesis. The photocatalysis experiments were developed under simulated solar light of 100 mW/cm2 and without using any sacrificial agent. To carry out this study, nanostructured mixed valence cobalt oxide (Co3O4) powders, with porous nanoparticle aggregates of different morphologies, have been prepared by two synthesis methods. The characterization of structural (PXRD, XPS, SEM, and TEM) and optical (UV-vis-NIR, Raman, and FT-IR) properties, magnetization curves, and surface area (BET) was accomplished