Epithelial tissue regeneration may be favored if the tissue receives both therapeutic agents such as recombinant human epidermal growth factor (rhEGF) and, simultaneously, antibacterial materials capable of reducing the risk of infections. Herein, we synthesized silver nanoparticles (AgNPs), which are well-known antibacterial materials, and impregnate them with rhEGF in order to study a bio-nanomaterial of potential interest for epithelial tissue regeneration. A suspension of Ag NPs is prepared by the chemical reduction method, employing sodium citrate as both a reducer and capping agent. The AgNPs suspension is mixed with a saline solution containing rhEGF, producing rhEGF-coated Ag NPs with rhEGF loadings between 0.1 and 0.4% w/w. ELISA assays of supernatants demonstrate that, in all studied cases, over 90% of the added rhEGF forms part of the coating, evidencing a high efficiency in i...

In spite of the widespread use of the chemical reduction method to obtain silver nanoparticles, the nanoparticle yield is often low due to a required addition of small volumes of diluted metal ions to a solution containing a reducer. Higher yields can be obtained following an alternative method, in which the reducer is added to a greater volume of silver ions in the solution. In this study, protocols for both methods are detailed and compared, using characterization tools such as UV-vis spectrometry, dynamic light scattering (DLS), and zeta potential measurements. By using this alternative method, the amount of silver in the solution is three times greater, and nanoparticles with a narrower size distribution are formed (between 6 and 70 nm in size). In contrast, the regular method produces particles of 3 and 100 nm. Zeta potential measurements indicate that the nanoparticles synthesized ...

Even though funding for culture and heritage-related projects is normally scarce, it is even more difficult to find in times of crisis. One option to fund heritage protection is the acquisition of research and development funds, which usually require tangible achievements or an explicit link to socio-economic development. The Research Center for Heritage Conservation in Lima, Peru, adopted the value-chain model from the business management sector to evaluate and determine the convenience of embarking on a conservation project. This value-chain for heritage follows three stages: Identification and evaluation, conservation, and dissemination of results, to pave the way for the development of sustainable practices in collections management. Having limited human resources and infrastructure, projects had to comply with four criteria: a well-documented problem, a clear hypothesis or objective...

Understanding the changes of a mineral during ore processing is of capital importance for the development of strategies aimed at increasing the efficiency of metal extraction. This task is often difficult due to the variability of the ore in terms of composition, mineralogy and texture. In particular, surface processes such as metal re-adsorption (preg-robbing) on specific minerals are difficult to evaluate, even though they may be of importance as the re-adsorbed material can be blocking the valuable mineral and negatively affect the extraction process. Here, we show a simple yet powerful approach, through which surface processes in individual minerals are identified by combining polarization microscopy (MP) and X-ray photoelectron spectroscopy (XPS). Taking as an example a silver-containing polymetallic sulfide ore from the Peruvian central Andes (pyrite-based with small amounts of gal...

Understanding the changes of a mineral during ore processing is of capital importance for the development of strategies aimed at increasing the efficiency of metal extraction. This task is often difficult due to the variability of the ore in terms of composition, mineralogy and texture. In particular, surface processes such as metal re-adsorption (preg-robbing) on specific minerals are difficult to evaluate, even though they may be of importance as the re-adsorbed material can be blocking the valuable mineral and negatively affect the extraction process. Here, we show a simple yet powerful approach, through which surface processes in individual minerals are identified by combining polarization microscopy (MP) and X-ray photoelectron spectroscopy (XPS). Taking as an example a silver-containing polymetallic sulfide ore from the Peruvian central Andes (pyrite-based with small amounts of gal...

The presence of copper in ores containing noble metals results in a high consumption of cyanide during leaching, which is undesirable from economic and environmental standpoints. Substantial previous work targets copper-gold ores, but the present study focuses on a copper-silver ore, which will be leached following acidic pretreatment (sulfuric acid at pH 1) to assess the effect of copper in cyanide consumption and silver extraction. The ore is mainly composed of hematite/goethite and silicates, with copper (0.15%) and silver (250 ppm) mostly present as sulfides and sulfosalts. The acidic pretreatment dissolves 18% of the copper content, which in turn decreases the cyanide consumption from 7 to 3 kg NaCN/ton in a five-hour leaching. Mineralogical changes, followed by polarization microscopy, are only minimal and restricted to iron oxides, while silicates and sulfides remain unchanged. Ho...

Silver nanoparticles (AgNPs) are known and widely used for their antibacterial properties. However, the ever-increasing resistance of microorganisms compels the design of novel nanomaterials which are able to surpass their capabilities. Herein, we synthesized silver nanoparticles using, for the first time, polyhydroxy fullerene (PHF) as a reducing and capping agent, through a one-pot synthesis method. The resulting nanoparticles (PHF-AgNPs) were compared to AgNPs that were synthesized using sodium citrate (citrate-AgNPs). They were characterized using high-resolution transmission electron microscopy (HR-TEM), dynamic light scattering, and UV-visible spectroscopy. Our results showed that PHF-AgNPs have a smaller size and a narrower size distribution than citrate-AgNPs, which suggests that PHF may be a better capping agent than citrate. Antibacterial assays using E. coli showed enhanced an...

Silver nanoparticles (AgNPs) are known and widely used for their antibacterial properties. However, the ever-increasing resistance of microorganisms compels the design of novel nanomaterials which are able to surpass their capabilities. Herein, we synthesized silver nanoparticles using, for the first time, polyhydroxy fullerene (PHF) as a reducing and capping agent, through a one-pot synthesis method. The resulting nanoparticles (PHF-AgNPs) were compared to AgNPs that were synthesized using sodium citrate (citrate-AgNPs). They were characterized using high-resolution transmission electron microscopy (HR-TEM), dynamic light scattering, and UV-visible spectroscopy. Our results showed that PHF-AgNPs have a smaller size and a narrower size distribution than citrate-AgNPs, which suggests that PHF may be a better capping agent than citrate. Antibacterial assays using E. coli showed enhanced an...