Síntese biogênica de nanopartículas de prata usando própolis vermelha de Alagoas

Abstract

The design and use of nanomaterials have been becoming a practice once more common in the las years, among inorganic nanoparticles, such as metallics, have been important for their optical and electrics unique properties, such as Surface Plasmon Resonance (SPR). However, their use still generates a series of questions due to its compatibility and toxicity. Thus, there is a pursue for new alternatives of synthesis and preparation less toxic, such as biogenic synthesis, which uses biological materials like propolis in metallic nanoparticles elaboration. Therefore, knowing the use of silver for antimicrobial activity and the innumerous range of properties from red propolis of Alagoas, the given work had as an aim to synthetize silver nanoparticles using red propolis of Alagoas (NPAg-PVA). In order to choose the most suitable conditions of synthesis for obtention of lower size of nanoparticles, was used factorial design 23 with statistic evaluation by Statistica (Statsoft®). Next, it was done the characterization of colloidal suspension by Ultra-Violet visible (UV-Vis) spectrophotometry, dynamic light scattering (DLS) and fluorimetry. The solid material isolated was analyzed by optical spectroscopy of emission (ICP-OES), powder X-Ray Diffraction (PXRD), Infrared Spectroscopy (FT-IR), Raman Spectroscopy, thermal analysis and scanning electronic microscopy (SEM). For antibacterial evaluation, has been used minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). As a results, it was obtained that the optimal condition of NPAg-PVA synthesis was an agitation of 650 rpm and 500 μM of silver nitrate (AgNO3) and 50 μg.mL-1 of PVA. With regards to colloidal suspension, was noticed the SPR band in 412 nm, confirming spherical NPAg-PVA formation. The mean hydrodynamic size was 109 nm, with a polydispersity index (PDI) of 0,207, representing an uniformity of size. Considering fluorescence, it was observed a quenching for NPAg-PVA in relation to propolis, besides a red shift from 448 to 472 nm. Evaluating stability was possible to note a gradual polydispersity of nanoparticles after 24h with PDI increasing. For powder characterization, for ICP-OES was obtained a silver yield of approximately 55% and PXRD demonstrated the main plains related to metallic silver (JCPDS 96-901-3051 in the degrees 2θ of 38,18°, 44,42°, 64,44° e 77,52° e 81,56°. For FTIR and Raman could be observed evidence of carbonyl and carboxyl groups’ participation on silver reduction and NPAg-PVA stability. Thermal analysis indicated around 22% (mass) for present organic material in NPAg-PVA and microscopy corroborated with UV-Vis and DLS findings respecting to spherical shape and size around 100 nm. Lastly, NPAg-PVA has evidenced potencial antibacterial activity, with more sensibility for Staphylococcus aureus (MIC = 8 μg.mL-1 e BMC = 32 μg.mL-1), confirming synergic action from its precursors.