One of the main issues in the medical field and clinical practice is the development of novel and effective treatments against infections caused by antibiotic-resistant bacteria. One avenue that has ...been approached to develop effective antimicrobials is the use of silver nanoparticles (Ag-NPs), since they have been found to exhibit an efficient and wide spectrum of antimicrobial properties. Among the main drawbacks of using Ag-NPs are their potential cytotoxicity against eukaryotic cells and the latent environmental toxicity of their synthesis methods. Therefore, diverse green synthesis methods, which involve the use of environmentally friendly plant extracts as reductive and capping agents, have become attractive to synthesize Ag-NPs that exhibit antimicrobial effects against resistant bacteria at concentrations below toxicity thresholds for eukaryotic cells.
In this study, we report a green one-pot synthesis method that uses
extract as a reducing and capping agent, to produce Ag-NPs with applications as therapeutic agents to treat infections in vivo.
The Ag-NPs were characterized using transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction, energy-dispersive spectroscopy, ultraviolet-visible, and Fourier transform infrared.
We show that Ag-NPs are spherical with a narrow size distribution. The Ag-NPs show antimicrobial activities in vitro against Gram-negative (
,
, and a clinical multidrug-resistant strain of
) and Gram-positive (
) bacteria. Moreover, antimicrobial effects of the Ag-NPs, against a resistant
clinical strain, were tested in a murine skin infection model. The results demonstrate that the Ag-NPs reported in this work are capable of eradicating pathogenic resistant bacteria in an infection in vivo. In addition, skin, liver, and kidney damage profiles were monitored in the murine infection model, and the results demonstrate that Ag-NPs can be used safely as therapeutic agents in animal models.
Together, these results suggest the potential use of Ag-NPs, synthesized by green chemistry methods, as therapeutic agents against infections caused by resistant and nonresistant strains.
The potential use of raw and expanded perlite as low-cost adsorbents for biogas purification has been investigated. The thermal expansion of perlite causes a reduction in the density of silanol ...groups from 2515.43 to 653.75 OH/nm2; in contrast, the specific surface area of perlite increased two-fold due to the thermal expansion. To determine the equilibrium adsorption capacity and the adsorption kinetics batch experiments were conducted. The adsorption capacities are in the following order: activated carbon (6.8 mg/g) > silica gel (6.6 mg/g) > expanded perlite (5.8 mg/g) > raw perlite (5.6 mg/g) when compared at the same experimental conditions. The equilibrium adsorption data showed that perlite can be used to reduce the octamethylcyclotetrasiloxane concentration below 28 mg/m3, as recommended by leading manufacturers. The adsorption kinetics of octamethylcyclotetrasiloxane onto raw and expanded perlite followed the Linear-Driving Force model suggesting that the mass transfer is the rate-controlling step. In addition to its low cost, expanded perlite has the advantage of requiring lower desorption temperature (200 °C) for regeneration in comparison to the reported values for activated carbon (>400 °C) and fast desorption kinetics (20 min), which could contribute to a cleaner production of biogas.
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•The density of silanol groups in perlite decrease 74% after thermal expansion.•Perlite has similar siloxane adsorption capacity than activated carbon and silica gel.•A long time is required for perlite to achieved adsorption equilibrium (170 h).•Perlite can reduce siloxane concentration to 28 mg/m3 as recommended by manufacturers.•Perlite showed fast desorption (20 min) and a low regeneration temperature (200 °C).
In this study, a simultaneous optimisation of technical and environmental parameters for activated carbon production from soybean shells is presented. A 23 factorial design was developed to explore ...the performance of the technical responses yield and iodine number, and the single score of ReCiPe endpoint method, which was evaluated by means the life cycle assessment. The independent factors included in the design of experiments were the impregnation ratio, temperature, and time activation. Three quadratic equations were obtained and simultaneously optimised by maximisation of the overall desirability function. The principal results of the individual responses indicate that the iodine number is practically independent of the activation temperature in a range of 450 ºC–650 ºC; the yield is inversely proportional to activation time and exhibits minimum values between 500 ºC–600 ºC; and the environmental response single score presents the lowest value at a temperature and time activation of 450 ºC and 30 min, respectively. The most polluting stage of activated carbon production from soybean shells production is the impregnation stage, mainly for the use of ZnCl2 as activating agent and the energy consumption. The simultaneous optimisation of the three responses indicates that the optimal activated carbon should be produced at 180 min, 650 ºC, and an impregnation ratio of 1 g soybean shell g ZnCl2-1.
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