What is it about?
Antimycotic behavior of zinc oxide decorated with silver nanoparticles (ZnO-AgNPs) against Trichophyton mentagrophytes (T. mentagrophytes) was investigated on this work. Silver decoration size was modulated during Ag2OandAg0 synthesis in aqueous solution at pH11, 12 and 14, obtaining the smallest size at pH12 and the largest at pH 14. In ex-situ tests, ZnO-AgNPs prevents successfully the growth of T. mentagrophytes, the percent mycelial inhibition (PMI) of formula F12 was 91.76% while formulas F12 and F14 was 100%, they also not present toxicity in cell viability, even the formula F12 promoted cell growth. Additionally, once T. mentagrophytes has grown it turns in a hydrophobic biofilm,whose water contact angle (WCA) was 127±3°, showing that no aqueous solution will have antimycotic activity against T. mentagrophytes biofilm. It has been propose a ZnO-AgNPs suspension in a hydrophobic fluid (polydimethylsiloxane, PDMS) that allowed to the particles permeate and permitted a direct contactwith the biofilm,which was eliminated successfully. These results suggest that ZnO-AgNPs in a hydrophobic fluid emerge as a viable alternative for fungal infections treatment.
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Why is it important?
The aim of this research is to demonstrate that zinc oxide decorated with silver nanoparticles can show antimycotic activity. To this purpose, the great potential of silver nanoparticles supported on ZnO offers a wide possibility of synthesis, which allows obtain highly dispersed materials in a nanometer size range controlled with pH synthesis under simple conditions. Depending on pH during the synthesis process, three formulations of ZnO-AgNPs were synthesized and evaluated at different doses against T. mentagrophytes growth. The biocidal activity of ZnO-AgNPs in aqueous and oily solution was tested on T. mentagrophytes biofilm, showing a more effectiveness the second one.
Perspectives
Three antimycotic formulas of zinc oxide decorated with silver nanoparticles (ZnO-AgNPs)were tested; the difference between them was pH value of the synthesis medium, synthesized formulas were F11 (pH = 11), F12 (pH = 12) and F14 (pH = 14). The synthesis is fast, simple and free of catalyst or surfactants. According to FTIR, XRD, XPS, TEM andDLS analysis, the main parameter influencing growth of silver particles due to the basic conditions. According to DLS, the average size of ZnO particles was 857.9 nm, while formulas F11, F12 and F12 were decorated with AgNPs getting diameters of 6.66 ± 2.67, 2.32 ± 0.82 and 10.39 ± 2.26 nm, its form was quasi-spherical-shape silver agglomerates, formed mostly by Ag2O and Ag0. Varying the concentrations of these formulas from 1 to 100 μg/mL, the antimycotic samples were non-toxic to osteoblasts, and based on cell viability itwas found that osteoblast proliferation is favored by sample F12 at a concentration from 1 to 10 μg/mL. ZnOAgNPs sinthetyzed under different pH proved observable antimycotic activity against T. mentagrophytes. The antimycotic activity was tested with the formulas located at the bottomof the agar container, but the diffusion to the surface of the ZnO-AgNPs particles was sufficient to inhibit the growth of the fungus. The percent mycelial inhibition (PMI) for formulas F11, F12 and F14was 88.23%, 85.88% and 81.76% of fungal growth, respectively. This indicates that particles diffusion was smaller when increasing its size. On the other hand, the antimycotic activity was tested by placing the particles on the surface of the solidified agar, which prevented the fungus growth; however, sample F11 with smaller pH synthesis shows slight growth (7 ± 0.05 mm), corresponding to a PMI of 91.76%, while PMI of formulas F12 and F14 was 100%. Besides, once the biofilm is formed, the aqueous solution does not present antimycotic activity due to the hydrophobic nature of biofilm (WCA 127 ± 3°). Since results of cell viability test and PMI suggest that the best formula was F12, we prepared suspensions of ZnO-AgNPs particles (formula F12) in PDMS,which is a hydrophobic fluid and allows creates a biocompatible interface. This suspension successfully inhibited the growth of T. mentagrophytes.
Dr Rosalba Patiño Herrera
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This page is a summary of: Antimycotic activity of zinc oxide decorated with silver nanoparticles against Trichophyton mentagrophytes, Powder Technology, March 2018, Elsevier,
DOI: 10.1016/j.powtec.2018.01.004.
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