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In this work, oxidized ordered mesoporous carbon (OMC-OXI) decorated with magnetite (OMC-OXI-Fe) was synthesized via a soft template technique in combination with a solvothermal method. The OMC-OXI-Fe was characterized by Raman spectroscopy, X-ray diffraction, nitrogen adsorption-desorption, scanning electron microscopy and thermal gravimetric analysis, indicating that the material keeps the OMC structure. The prepared material was used as an electrochemical sensor for the single and combined detection of Cd(II), Cu(II), Hg(II), and Pb(II) ions by square-wave anodic stripping voltammetry (SWASV). The electrochemical results showed that incorporation of magnetite did not modify the charge transfer properties, and maintained the available surface area for the metal ion detection. OMC-OXI-Fe presented a very favorable sensitivity (145.75 μA mg−1 L) and LOD (1.57 μg L−1) for Pb(II), while the responses to Cu(II), Cd(II) and Hg(II) were much lower. These results indicated that the magnetic properties of the modified electrode increased the individual sensitivity for Pb(II) detection and maintained the capacity of simultaneous detection for the studied heavy metal ions. The combination of magnetic mesoporous carbon and electrochemical pulse techniques is a suitable and practical alternative method for the electrochemical detection of hazardous metallic ions in water for human use.

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Quantum chemical calculations were performed to characterize the interaction of the flavonol molecule (FL) with methacrylic acid (MAA) and 4-vinylpyridine (4VPy) in the formation of imprinted polymers. The polarizable continuum model (PCM) was used to gain insight on the type of interaction between the reactant molecules under vacuum conditions and in the presence of different solvents. The effect of solvent on the pre-polymerization complex formation was evaluated through the stability energy, in which chloroform behaves as the best solvent for the synthesis of the imprinted polymers since it facilitates the reaction by lowering its degree of stabilization. The reactivity was analyzed in terms of the electrostatic surface potential (ESP) and Mulliken charge. By means of these results, it has been possible to determine two potential recognition sites for the interaction of the MAA monomer and one for the 4VPy in relation to the strength of interaction with FL. In this concern, the interaction of the system FL-MAA is stronger than FL-4VPy.

AbstractPorous polymeric scaffolds have been applied successfully in the biomedical field. This work explores the use of an ultrasonic probe to generate cavitation in a polymeric solution, thus producing pores in the polymeric scaffolds. Porous polymeric structures with average pore sizes ranging from 5 to 63 μm and porosity of 6–44% were fabricated by a process consisting of sonication, flash freezing, and lyophilization of poly(lactic-co-glycolic acid) (PLGA), gelatin (GEL), chitosan (CS) and poly(vinyl alcohol) (PVAL) solutions. Pore structure was characterized by scanning electron microscopy (SEM) and image analysis software. The infrared spectra were analyzed before and after the fabrication process to observe any change in the chemical structure of the polymers. A water absorption test indicated the susceptibility of the samples to retain water in their structure. TGA results showed that GEL experienced degradation at 225°C, CS had a decomposition peak at 280°C, the thermal decomposition of PLGA occurred at 375°C, and PVAL showed two degradation regions. The DSC analysis showed that the glass transition temperature (Tg) of GEL, CS, PLGA and PVAL occurred at 70°C, 80°C, 60°C and 70°C, respectively. The fabricated porous structures demonstrated similar physical characteristics to those found in bone and cartilage.