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One-step eco-friendly synthesized silver-graphene oxide/poly(vinyl alcohol) antibacterial nanocomposites

En nuestra última publicación en la revista Carbon hemos estudiado nuevos materiales antimicrobianos basados en la plata y el grafeno. Este estudio de las propiedades de nuevos materiales lo hemos desarrollado en la Facultad de Química y la Facultad de Medicina y Enfermería de la Universidad del País Vasco (UPV/EHU), Mónica Cobos, Iker De-La-Pinta, María Jesús Fernández, María Dolores Fernández y Guillermo Quindós.

Este es el resumen:

Due to the increasing occurrence and spread of antibiotic resistance pathogenic microorganisms, the development of antimicrobial materials has emerged as a strategy to control the bacterial activity and transmission. In this study, poly(vinyl alcohol)/silver nanoparticles-graphene oxide (PVA/AgNPs-GO) nanocomposites were synthesized by a one-step process with l-ascorbic acid as environmentally friendly reductant agent of a mixture of AgNO3, GO and PVA aqueous solutions. PVA/GO nanocomposites were also prepared for comparison. The structure, morphology, thermal, mechanical, water resistance and antibacterial properties of the samples were investigated as a function of GO and silver precursor contents. GO sheets decorated with spherical AgNPs were uniformly dispersed in the polymer matrix. The size range of most AgNPs was below 10 nm. Nanocomposites exhibited higher glass transition and crystallization temperatures. Thermal stability, mechanical and water resistance properties of PVA enhanced when GO was incorporated, and it was more remarkable in the presence of AgNPs-GO. PVA/AgNPs-GO nanocomposites showed antibacterial activity against Gram negative bacteria Escherichia coli and against Gram positive bacteria Staphylococcus aureus, being its efficiency dependent on exposure time and AgNPs precursor concentration. In contrast, PVA/GO films showed no activity against both bacteria over the GO loading range investigated. PVA/AgNPs-GO nanocomposites may be potential wound dressings.

Graphical abstract

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Killing kinetics of anidulafungin, caspofungin and micafungin against Candida parapsilosis species complex: Evaluation of the fungicidal activity

En esta publicación en la Revista Iberoamericana de Micología mostramos la alta eficacia de las equinocandinas, anidulafungina, caspofungina y micafungina contra los aislamientos clínicos de Candida parapsilosis, Candida metapsilosisCandida orthopsilosis, especies emergentes de Candida. Es un estudio que hemos realizado en la Facultad de Medicina y Enfermería de la Universidad del País Vasco (UPV/EHU)Sandra Gil-Alonso, Nerea Jauregizar, Elena Eraso y Guillermo Quindós. Hemos contado con la inestimable ayuda de Emilia Cantón del Hospital Universitario y Politécnico La Fe (Valencia).

Este es el resumen:

Candida parapsilosis, Candida metapsilosis and Candida orthopsilosis are emerging as relevant causes of candidemia. Moreover, they show differences in their antifungal susceptibility and virulence. The echinocandins are different in terms of in vitro antifungal activity against Candida. Time-kill (TK) curves represent an excellent approach to evaluate the fungicidal activity of antifungal drugs.

AIMS:

To compare the fungicidal activities of anidulafungin, caspofungin and micafungin against C. parapsilosis species complex by TK curves.

METHODS:

Antifungal activities of three echinocandins against C. parapsilosis, C. metapsilosis and C. orthopsilosis were studied by TK curves. Drug concentrations assayed were 0.25, 2 and 8μg/ml. CFU/ml were determined at 0, 2, 4, 6, 24 and 48h.

RESULTS:

Killing activities of echinocandins were species-, isolates- and concentration-dependent. Anidulafungin reached the fungicidad endpoint for 6 out of 7 isolates (86%); it required between 13.34 and 29.67h to reach this endpoint for the three species studied, but more than 48h were needed against one isolate of C. orthopsilosis (8μg/ml). Caspofungin fungicidal endpoint was only achieved with 8μg/ml against one isolate of C. metapsilosis after 30.12h (1 out of 7 isolates; 14%). Micafungin fungicidal endpoint was reached in 12.74-28.38h (8μg/ml) against one isolate each of C. parapsilosis and C. orthopsilosis, and against both C. metapsilosis isolates (4 out of 7 isolates; 57%).

CONCLUSIONS:

C. metapsilosis was the most susceptible species to echinocandins, followed by C. orthopsilosis and C. parapsilosis. Anidulafungin was the most active echinocandin against C. parapsilosis complex.

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