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The Cu(II)/Cu(I) conversion involves variation in the coordination number and geometry around the metal center. Therefore, the flexibility/rigidity of the ligand plays a critical role in the design of copper superoxide dismutase (SOD) mimics. A 1,3-Bis[(pyridin-2-ylmethyl)(propargyl)amino]propane (pypapn), a flexible ligand with an N4-donor set, was used to prepare [Cu(pypapn)(ClO4)2], a trans-Cu(II) complex whose structure was determined by the X-ray diffraction. In DMF or water, perchlorate anions are exchanged with solvent molecules, affording [Cu(pypan)(solv)2]2+ that catalyzes O2•− dismutation with a second-order rate constant kMcF = 1.26 × 107 M−1 s−1, at pH 7.8. This high activity results from a combination of ligand flexibility, total charge, and labile binding sites, which places [Cu(pypapn)(solv)2]2+ above other mononuclear Cu(II) complexes with more favorable redox potentials. The covalent anchoring of the alkyne group of the complex to azide functionalized mesoporous silica through “click” chemistry resulted in the retention of the SOD activity and improved stability. A dicationic Cu(II)-N4-Schiff base complex encapsulated in mesoporous silica was also tested as an SOD mimic, displaying higher activity than the free complex, although lower than [Cu(pypapn)(solv)2]2+. The robustness of covalently attached or encapsulated doubly charged Cu(II) complexes in a mesoporous matrix appears as a suitable approach for the design of copper-based hybrid catalysts for O2•− dismutation under physiological conditions.

In low-molecular-weight Mn superoxide dismutase (SOD) mimics, the ligand plays a key role in tuning the reactivity of the metal center with O2•−. We used three ligands differing in their donor sites, flexibility and/or charge, to compare the redox properties and SOD activity of the resulting Mn complexes: 1,3-bis[(pyridin-2-ylmethyl)(propargyl)amino]propane (pypapn), 1,3-bis(pyridin-2-ylmethyleneamino)propane (py2pn) and 1,4-bis(salicylidenamino)butane (H2salbn). These ligands afford Mn complexes that, in aqueous solution, exist as mononuclear species [Mn(II)(pypapn)(H2O)2]2+, [Mn(II)(py2pn)(H2O)2]2+ and [Mn(III)(salbn)(H2O)2]+. The relative reactivity of these compounds with O2•− at pH 7.8, [Mn(pypapn)(H2O)2]2+ > [Mn(salbn)(H2O)2]+ > [Mn(py2pn)(H2O)2]2+, is independent of the redox potential but strongly depends on the ligand flexibility which becomes a critical feature when the reaction occurs through an inner-sphere electron-transfer mechanism. Immobilization was used to isolate and protect the catalyst from dissociation or dimerization during catalysis. [Mn(pypapn)(H2O)2]2+, with the alkyne group, was covalently grafted to azide functionalized mesoporous silica through click chemistry, while [Mn(py2pn)(solv)2]2+ and [Mn(salbn)(solv)2]+ were encapsulated in SBA-15 mesoporous silica through ionic exchange. The retention or enhancement of the SOD activity and the improved stability of the covalently attached catalyst and the doubly charged complex encapsulated in the silica pores, make them suitable for use in aqueous media.

Abstract Malassezia furfur is lipophilic and lipid-dependent yeast, inhabitant of human skin microbiota associated with several dermal disorders. In recent years, along with the advances in nanotechnology and the incentive to find new antimicrobial drugs, there has been a growing interest in the utilization of nanoparticles for the treatment of skin microbial infections. This work aimed to study the in vitro inhibitory activity of silver nanoparticles (AgNP) against 41 M. furfur clinical isolates, visualize the interaction between AgNP-Malassezia, evaluate the synergism with ketoconazole (KTZ) and to produce an antimicrobial gel of AgNP–KTZ. The synthesized AgNP were randomly distributed around the yeast surface and showed a fungicidal action with low minimal inhibitory concentration values. AgNP showed no antagonistic effect with KTZ. The broad-spectrum antimicrobial property with fungicidal action of AgNP and its accumulation in affected areas with a sustained release profile, added to the great antifungal activity of KTZ against Malassezia infections and other superficial mycoses, allowed us to obtain a gel based on carbopol formulated with AgNP–KTZ with the potential to improve the topical therapy of superficial malasseziosis, reduce the number of applications and, also, prevent the recurrence.

El presente trabajo plantea de qué manera el enfoque de planificación estratégica asociado al campo educativo impacta y modifica las perspectivas y posicionamientos de los docentes que se atreven a conocerlo e implementarlo en sus propuestas pedagógicas. En el presente trabajo además se ponen a prueba los postulados fundamentales del enfoque estratégico ayudados por uno de sus exponentes más importantes: Henry Minztberg. En la actualidad, la aplicación del enfoque estratégico en el ámbito de la educación genera interrogantes frente a los cuales es necesario volver la mirada para no desvirtuar las propuestas, pretendiendo encorsetar realidades sociales singulares que se modifican cotidianamente. De ningún enfoque de planeamiento pueden esperarse resultados mágicamente satisfactorios. Asumido lo anterior, es necesario dilucidar qué significa para el docente y las instituciones educativas la implementación del enfoque estratégico en sus prácticas cotidianas.