Luis Cumbal

We reported an ecofriendly method for the phytosynthesis of silver nanoparticles (AgNPs) using the pollen of double-petal China rose/Hibiscus rosa-sinensis as a natural reducing and stabilizing agent. The phytosynthesized AgNPs were preliminary characterized by their optical properties by UV–vis spectroscopy and showed their corresponding surface plasmonic resonance (SPR) at 405 nm. The distribution pattern and morphology of the synthesized AgNPs were confirmed by dynamic light scattering and transmission electron microscopy whereas X-ray diffraction and Fourier transform infrared spectroscopy depicts their surface properties and crystalline nature. The phytosynthesized AgNPs were spherical, well dispersed, 10–50 nm in size, and crystalline. It also showed moderate photocatalytic activity for the degradation (>30%, 2.5 h) of Thioflavin T dye in direct sunlight. Thus, this work highlights the importance of China rose pollen in green nanoscience and supports the cleanliness of nature by naturally available materials.

The predominant aim of the current study was to synthesize the nanofertilizer nanoparticles ZnO_MnO-NPs and FeO_ZnO-NPs using Andean blueberry extract and determine the effect of NPs in the growth promotion of cabbage (Brassica oleracea var. capitata) and Andean lupin (Lupinus mutabilis sweet) crops. The nanoparticles were analyzed by visible spectrophotometry, size distribution (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Solutions of nanoparticle concentrations were applied to cabbage, with solutions of 270 and 540 ppm of ZnO_MnO-NPs and 270 and 540 ppm of FeO_ZnO-NPs applied to Andean lupin. Zinc was used in both plants to take advantage of its beneficial properties for plant growth. Foliar NPs sprays were applied at the phenological stage of vegetative growth of the cabbage or Andean lupin plants grown under greenhouse conditions. The diameter of the NPs was 9.5 nm for ZnO, 7.8 nm for FeO, and 10.5 nm for MnO, which facilitate the adsorption of NPs by the stomata of plants. In Andean lupin, treatment with 270 ppm of iron and zinc indicated increases of 6% in height, 19% in root size, 3.5% in chlorophyll content index, and 300% in leaf area, while treatment with 540 ppm of iron and zinc yielded no apparent increases in any variable. In cabbage, the ZnO_MnO-NPs indicate, at a concentration of 270 ppm, increases of 10.3% in root size, 55.1% in dry biomass, 7.1% in chlorophyll content, and 25.6% in leaf area. Cabbage plants treated at a concentration of 540 ppm produced increases of 1.3% in root size and 1.8% in chlorophyll content, compared to the control, which was sprayed with distilled water. Therefore, the spray application of nanofertilizers at 270 ppm indicated an important improvement in both plants’ growth.

In this work, we describe a simplified and bottom-up synthesis of silver nanoparticles (AgNPs) using pollen collected by Andean honeybees as a natural reducing and capping agent for the first time. The biosynthesized AgNPs were characterized by their optical properties, electrochemical properties, average size, morphology, and purity by various analytical techniques. The synthesized AgNPs were spherical, having 10–35 nm size, showed λ_max at 440 nm, well dispersed, and remained stable for up to 1 month under laboratory conditions without any sedimentation. Moreover, we also investigated the usability of synthesized AgNPs as antioxidants against 1, 1-diphenyl-2-picrylhydrazyl (DPPH). Thus, this protocol may be adapted for the large-scale production of nanoparticles without the use of chemical solvents and supports the importance of local resources in green chemistry. Graphical Abstract

In the present study, we report a simple and ecofriendly phytosynthesis of silver nanoparticles (AgNPs) using fruits of Capsicum baccatum L. (Andean chili). During the reaction, the phytoconstituents of C. baccatum act as a reducing and stabilizing agent. Phyotsynthesized AgNPs were characterized through various spectroscopy and microscopic techniques. The produced AgNPs showed a plasmon band at λ_max = 458 nm and stable for 10 days, confirmed by UV-vis spectroscopy. Transmission electron microscopy (TEM) explained that the produced AgNPs were quasi-spherical in shape with an average size of 10–30 nm and small aggregation. The X-ray diffraction analysis confirmed the crystalline nature of the AgNPs. Aggregation of AgNPs was indicated in the dynamic light scattering (DLS) and TEM analysis. AgNPs also exhibited quenching/sensing activity of H₂O₂ (>50%) at room temperature. The results demonstrate that as-synthesized AgNPs are inexpensive, sustainable and could be an alternative as optical chemical sensors.

In this study, silver nanoparticles (AgNPs) were obtained using a green-chemistry procedure. For this protocol, the Carrasquilla extract (CE) (Berberis hallii) and a AgNO₃ solution were used as the reducing agent and the metal precursor, respectively. The as-prepared AgNPs after characterization were then used to evaluate the degradation of the methylene blue (MB), the safranin (SF), and the mixture of both dyes in the aqueous phase under solar light irradiation. The photocatalytic activity of AgNPs for the degradation of the MB (k = 0.0092 min⁻¹) was higher than the SF (k = 0.00016 min⁻¹) due to the susceptibility of the thiazine ring of the MB to photodegradation contrasted to the phenyl phenazine of the SF. However, SF was mostly removed by adsorption with a maximum uptake of 2907 mg/g. Overall, this eco-friendly and green conversion of silver ions to metallic elements avoids the use of toxic chemicals and could be applied for the degradation/adsorption of dyes used in several industrial processes.