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Zinc oxide nanoparticles (ZnONPs) was produced using Ilex paraguariensis (mate) leaves extract using a green synthesis process. The influence of ethanolic and aqueous plant extract and zinc source on the green synthesis of ZnONPs was studied. Cyclic voltammetry and Fourier transform infrared spectroscopy (FTIR) were used for the assessment of the mechanism route of ZnONPs while the formation of this nanomaterial was confirmed by X-ray diffraction (XRD) analysis. The morphology and size of the ZnONPs synthesized were evaluated using field emission scanning microscopy (FESEM) and transmission electron microscopy (TEM) analysis. In general, all different synthesized ZnONPs exhibited a hexagonal crystalline structure whereas the size and shape varied depending on the extract and zinc salt used. Nonetheless, the most uniform and smallest ZnONPs were obtained using ethanolic extract and zinc nitrate, showing spherical morphology and a diameter of about 18 nm. With the use of cyclic voltammetry and FTIR analysis, it was concluded that the formation of ZnONPs through green synthesis occurred due to complexation of Zn(II) ions by antioxidants compounds present in the Ilex paraguariensis extract and further thermal degradation of the complexes. Concerning the cytotoxicity assays, the L929 cell viability decreases in a dose-dependent manner for all samples tested. In general, nanoparticles with reduced size and uniform shape exhibited no cytotoxic effects up to a concentration of 10 μ g mL−1. However, higher ZnONPs concentrations caused a decrease in cell viability. This was possibly due an autophagic induction process triggered by the internalization of the nanomaterial. Finally, this work provides a better understanding of the mechanism route to obtain ZnONPs via green method and their potential to be used as a biomedical material.

Traditional methods for synthesizing metallic nanoparticles include the use of toxic chemicals, which can have negative impacts on the environment and human health. A safer alternative to produce these nanomaterials is based on the concept of Green Chemistry, which uses less harmful chemicals from renewable sources. In this work, we describe a specific approach for the green synthesis of silver nanoparticles (AgNPs) using the extract of Ives cultivar (Vitis labrusca) pomace, their characterization, and their immobilization in a polymer matrix of chitosan aiming the disinfection of a raw wastewater sample. The influence of some experimental parameters on synthesis such as pH, stabilization time as well as the temperature has been investigated. The grape pomace extract was initially characterized regarding its content of phenolic compounds and then used as stabilizing-reducing agent. The obtained AgNPs were analyzed by ultraviolet-visible spectroscopy, transmission electron microscopy, zeta potential, scanning electron microscopy coupled with energy dispersive spectroscopy, and raman spectroscopy. In general, the AgNPs were spherical in shape and very stable. Aiming to explain the reaction, we also proposed a mechanism of formation of AgNPs based on gallic acid molecule. Concerning the antimicrobial properties, the results demonstrated the synergistic activity of chitosan-AgNPs pellets against Gram-positive and Gram-negative bacteria. Additionally, these materials led to a reduction of 47% of the bacterial count of Escherichia coli on the disinfection of the wastewater. Finally, it was concluded that the extract of Ives cultivar pomace is capable of producing stable AgNPs that can be used as auxiliaries in wastewater disinfection.