Browsing by Author "Ponce Montalvo, Jhonny David"

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    Elaboración de nanopartículas de metales de transición soportados en una matriz de propóleo y quitosano mediante electrospinning, como posible antifúngico
    (Universidad de Cuenca, 2020-07-07) Alvarado López, Marco Francisco; Ponce Montalvo, Jhonny David; Cruzat Contreras, Christian Américo
    Diseases in crops are caused by biotic factors that alter the physiological functions of plants and in extreme cases causing the death of plantations, among these factors are fungi. The strategies used by farmers to avoid losses in their crops due to fungal pathogen infestations include the application of chemical synthesis pesticides. However, controlled fungal populations can generate resistance, causing serious problems for growers. The objective of this study is to develop a new fungicide from obtaining a polymer matrix doped with transition metal nanoparticles (iron and zinc) supported on a polymeric matrix of chitosan and refined propolis. For this, we obtained the nanoparticles using the solvothermal technique, a reason for their simplicity and for involving accelerated reaction kinetics. Propolis was used since it has antimicrobial and antifungal properties, this associated with the large amount of flavonoids, polyphenols, steroids, aldehydes, symptoms and quinones, to whom these capacities are conferred. Nanoparticle syntheses were performed by varying reaction parameters (temperature, time and Zinc precursor). In the case of polymeric matrices, films of four types were obtained: chitosan, chitosan / propolis extract, chitosan / nanoparticles and chitosan / propolis extract / nanoparticles. Differential scanning calorimetry determined an increase in thermal stability in the matrices that had propolis and a lower water content. Transmission electron microscopy, electron diffraction of selected area and X-ray diffraction, demonstrated the structure of the nanoparticles, being these in greater quantity than the iron spinel (Fe3O4). Scanning electron microscopy determined a nanofilm-like structure of the electrospun polymer matrices. The release tests were adjusted to mathematical models, the Korsmeyer and Peppas model being the best fit, where propolis was the only substance that was released into the medium (70% ethanol). Finally, the antifungal activity of the nanoparticles, polymer matrices and solutions used in electrospinning was determined by means of an in vitro test against the fungus Fusarium sp.