by Keyword: Silver

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De Matteis, Valeria, Rizzello, Loris, Ingrosso, Chiara, Liatsi-Douvitsa, Eva, De Giorgi, Maria Luisa, De Matteis, Giovanni, Rinaldi, Rosaria, (2019). Cultivar-dependent anticancer and antibacterial properties of silver nanoparticles synthesized using leaves of different Olea Europaea trees Nanomaterials 9, (11), 1544

The green synthesis of nanoparticles (NPs) is currently under worldwide investigation as an eco-friendly alternative to traditional routes (NPs): the absence of toxic solvents and catalysts make it suitable in the design of promising nanomaterials for nanomedicine applications. In this work, we used the extracts collected from leaves of two cultivars (Leccino and Carolea) belonging to the species Olea Europaea, to synthesize silver NPs (AgNPs) in different pH conditions and low temperature. NPs underwent full morphological characterization with the aim to define a suitable protocol to obtain a monodispersed population of AgNPs. Afterwards, to validate the reproducibility of the mentioned synthetic procedure, we moved on to another Mediterranean plant, the Laurus Nobilis. Interestingly, the NPs obtained using the two olive cultivars produced NPs with different shape and size, strictly depending on the cultivar selected and pH. Furthermore, the potential ability to inhibit the growth of two woman cancer cells (breast adenocarcinoma cells, MCF-7 and human cervical epithelioid carcinoma, HeLa) were assessed for these AgNPs, as well as their capability to mitigate the bacteria concentration in samples of contaminated well water. Our results showed that toxicity was stronger when MCF-7 and Hela cells were exposed to AgNPs derived from Carolea obtained at pH 7 presenting irregular shape; on the other hand, greater antibacterial effect was revealed using AgNPs obtained at pH 8 (smaller and monodispersed) on well water, enriched with bacteria and coliforms.

Keywords: Green synthesis, Silver nanoparticles, Olea Europaea, Leccino, Carolea, Cytotoxicity, Genotoxicity, Antibacterial activity

Tahirbegi, I. B., Pérez, Y., Mir, M., Samitier, J., (2019). Counterions effect on uracil-silver coordination Inorganica Chimica Acta 490, 246-253

Cyanide based silver electroplating is a low-cost reliable and well-established process for metal deposition. However, delicate handling during the process is needed because of the high toxicity of cyanide, for the persons and the environment. Uracil based silver electrodeposition got the attention of this field, because of its low cost and non-toxic nature. However, little is known about the silver complexation with uracil and the process behind the silver electroplating. In this work, we studied a hitherto unknown phenomenon on the diverse structure’s formation of silver uracil coordination complex due to the presence of different alkaline counterions. The distinct structuration of this complex clearly impacts on the efficiency and deposition yields of silver electroplating. We demonstrate the unknown key role that play hydroxide counterions in the uracil-silver coordination, and the different molecular structures created on the basis of the used counterion. The hydroxide counterion determines monomeric and polymeric complex formation with silver, which affects the solubility of the uracil silver complex and its subsequent electrodeposition. The different molecular complexes were characterized by FT-IR, UV–vis, DRUV–vis and multi-nuclear NMR spectroscopy and the silver electrodeposition by cyclic voltammetry and TOF-SIMS. This study sheds some light in the improvement of silver electroplating process

Keywords: Coordination complex, Electrometallization, Electroplating, Metal complex, Silver electrodeposition, Uracil

Vilela, D., Stanton, M. M., Parmar, J., Sánchez, S., (2017). Microbots decorated with silver nanoparticles kill bacteria in aqueous media ACS Applied Materials & Interfaces 9, (27), 22093-22100

Water contamination is one of the most persistent problems of public health. Resistance of some pathogens to conventional disinfectants can require the combination of multiple disinfectants or increased disinfectant doses, which may produce harmful byproducts. Here, we describe an efficient method for disinfecting Escherichia coli and removing the bacteria from contaminated water using water self-propelled Janus microbots decorated with silver nanoparticles (AgNPs). The structure of a spherical Janus microbot consists of a magnesium (Mg) microparticle as a template that also functions as propulsion source by producing hydrogen bubbles when in contact with water, an inner iron (Fe) magnetic layer for their remote guidance and collection, and an outer AgNP-coated gold (Au) layer for bacterial adhesion and improving bactericidal properties. The active motion of microbots increases the chances of the contact of AgNPs on the microbot surface with bacteria, which provokes the selective Ag+ release in their cytoplasm, and the microbot self-propulsion increases the diffusion of the released Ag+ ions. In addition, the AgNP-coated Au cap of the microbots has a dual capability of capturing bacteria and then killing them. Thus, we have demonstrated that AgNP-coated Janus microbots are capable of efficiently killing more than 80% of E. coli compared with colloidal AgNPs that killed only less than 35% of E. coli in contaminated water solutions in 15 min. After capture and extermination of bacteria, magnetic properties of the cap allow collection of microbots from water along with the captured dead bacteria, leaving water with no biological contaminants. The presented biocompatible Janus microbots offer an encouraging method for rapid disinfection of water.

Keywords: Bactericidal, Magnetic control, Micromotors, Microswimmers, Self-propulsion, Silver nanoparticles

Simmchen, Juliane, Baeza, Alejandro, Miguel-Lopez, Albert, Stanton, Morgan M., Vallet-Regi, Maria, Ruiz-Molina, Daniel, Sánchez, Samuel, (2017). Dynamics of novel photoactive AgCl microstars and their environmental applications ChemNanoMat , 3, (1), 65-71

In the field of micromotors many efforts are taken to find a substitute for peroxide as fuel. While most approaches turn towards other toxic high energy chemicals such as hydrazine, we introduce an energy source that is widely used in nature: light. Light is an ideal source of energy and some materials, such as AgCl, have the inherent property to transform light energy for chemical processes, which can be used to achieve propulsion. In the case of silver chloride, one observed process after light exposure is surface modification which leads to the release of ions generating chemo-osmotic gradients. Here we present endeavours to use those processes to propel uniquely shaped micro objects of micro star morphology with a high surface to volume ratio, study their dynamics and present approaches to go towards real environmental applications.

Keywords: Self-propellers, Silver chloride, Environmental applications, Photoactive colloids, Anti bacterial

Gustavsson, J., Ginebra, M. P., Planell, J., Engel, E., (2012). Electrochemical microelectrodes for improved spatial and temporal characterization of aqueous environments around calcium phosphate cements Acta Biomaterialia 8, (1), 386-393

Calcium phosphate compounds can potentially influence cellular fate through ionic substitutions. However, to be able to turn such solution-mediated processes into successful directors of cellular response, a perfect understanding of the material-induced chemical reactions in situ is required. We therefore report on the application of home-made electrochemical microelectrodes, tested as pH and chloride sensors, for precise spatial and temporal characterization of different aqueous environments around calcium phosphate-based biomaterials prepared from α-tricalcium phosphate using clinically relevant liquid to powder ratios. The small size of the electrodes allowed for online measurements in traditionally inaccessible in vitro environments, such as the immediate material-liquid interface and the interior of curing bone cement. The kinetic data obtained has been compared to theoretical sorption models, confirming that the proposed setup can provide key information for improved understanding of the biochemical environment imposed by chemically reactive biomaterials.

Keywords: Calcium phosphate, Hydroxyapatite, Ion sorption, Iridium oxide, Sensors, Animals, Biocompatible Materials, Bone Cements, Calcium Phosphates, Cells, Cultured, Chlorides, Electrochemical Techniques, Gold, Hydrogen-Ion Concentration, Hydroxyapatites, Iridium, Materials Testing, Microelectrodes, Powders, Silver, Silver Compounds, Water