by Keyword: Silver

García-Mintegui, C, Chausse, V, Labay, C, Mas-Moruno, C, Ginebra, MP, Cortina, JL, Pegueroles, M, (2024). Dual peptide functionalization of Zn alloys to enhance endothelialization for cardiovascular applications Applied Surface Science 645, 158900

A new generation of fully bioresorbable metallic Zn-based alloys could be used for stenting applications; however, the initial surface degradation delays stent re-endothelialization. Thus, this work proposes a dual strategy to control the corrosion and accelerate the endothelialization of ZnMg and ZnAg biodegradable alloys. First, a stable polycaprolactone (PCL) coating is obtained and followed by its functionalization with either linear RGD (Arg-Gly-Asp) or REDV (Arg-Glu-Asp-Val) peptides or a dual peptide-based platform combining both sequences (RGD-REDV). Scratching tests showed neither delamination nor detachment of the polymeric coating. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements confirmed the corrosion resistance after PCL coating by revealing lower current density and higher absolute impedance values. X-ray photoelectron spectroscopy (XPS) and fluorescent microscopy confirmed the correct peptide immobilization onto PCL coated Zn alloys. The functionalized samples exhibited enhanced human umbilical vein endothelial cells (HUVEC) adhesion. The higher number of adhered cells to the functionalized surfaces with the RGD-REDV platform demonstrates the synergistic effect of combining both RGD and REDV sequences. Higher corrosion resistance together with enhanced endothelialization indicates that the dual functionalization of Zn alloys with PCL and peptide-based RGD-REDV platform holds great potential to overcome the clinical limitations of current biodegradable metal stents.

JTD Keywords: Binary alloys, Biodegradable metals, Bioresorbable, Cardiovascular applications, Cell adhesive peptides, Corrosion, Corrosion resistance, Corrosion resistant alloys, Corrosion resistant coatings, Degradation, Dual peptide-based platform, Electrochemical corrosion, Electrochemical impedance spectroscopy, Endothelial cells, Endothelialization, Functionalization, Functionalizations, In-vitro, Magnesium alloys, Metallics, Mg alloy, Peptides, Polycaprolactone coating, Polymer-coatings, Rgd-functionalization, Silver alloys, Stents, Surface, X ray photoelectron spectroscopy, Zinc, Zinc alloys, Zn alloys, Zn-based alloys

Mingot, J, Benejam, N, Víllora, G, Alemán, C, Armelin, E, Lanzalaco, S, (2023). Multimodal Biomedical Implant with Plasmonic and Simulated Body Temperature Responses Macromolecular Bioscience 23, e2300118

This work presents a novel nanoparticle-based thermosensor implant able to reveal the precise temperature variations along the polymer filaments, as it contracts and expands due to changes in the macroscale local temperature. The multimodal device is able to trace the position and the temperature of a polypropylene mesh, employed in abdominal hernia repair, by combining plasmon resonance and Raman spectroscopy with hydrogel responsive system. The novelty relies on the attachment of the biocompatible nanoparticles, based on gold stabilized by a chitosan-shell, already charged with the Raman reporter (RaR) molecules, to the robust prosthesis, without the need of chemical linkers. The SERS enhanced effect observed is potentiated by the presence of a quite thick layer of the copolymer (poly(N-isopropylacrylamide)-co-poly(acrylamide)) hydrogel. At temperatures above the LCST of PNIPAAm-co-PAAm, the water molecules are expulsed and the hydrogel layer contracts, leaving the RaR molecules more accessible to the Raman source. In vitro studies with fibroblast cells reveal that the functionalized surgical mesh is biocompatible and no toxic substances are leached in the medium. The mesh sensor opens new frontiers to semi-invasive diagnosis and infection prevention in hernia repair by using SERS spectroscopy. It also offers new possibilities to the functionalization of other healthcare products.© 2023 Wiley-VCH GmbH.

JTD Keywords: adhesion, blends, chitosan, gold nanoparticles, poly(n-isopropylacrylamide), polypropylene mesh, polypropylene meshes, repair, scattering, silver, surgical implants, thermosensitive hydrogels, toxicity, Chitosan, Gold nanoparticles, Polypropylene meshes, Surgical implants, Thermosensitive hydrogels

Moreno, D, Buxadera-Palomero, J, Ginebra, MP, Manero, JM, Martin-Gómez, H, Mas-Moruno, C, Rodríguez, D, (2023). Comparison of the Antibacterial Effect of Silver Nanoparticles and a Multifunctional Antimicrobial Peptide on Titanium Surface International Journal Of Molecular Sciences 24, 9739

Titanium implantation success may be compromised by Staphylococcus aureus surface colonization and posterior infection. To avoid this issue, different strategies have been investigated to promote an antibacterial character to titanium. In this work, two antibacterial agents (silver nanoparticles and a multifunctional antimicrobial peptide) were used to coat titanium surfaces. The modulation of the nanoparticle (≈32.1 ± 9.4 nm) density on titanium could be optimized, and a sequential functionalization with both agents was achieved through a two-step functionalization method by means of surface silanization. The antibacterial character of the coating agents was assessed individually as well as combined. The results have shown that a reduction in bacteria after 4 h of incubation can be achieved on all the coated surfaces. After 24 h of incubation, however, the individual antimicrobial peptide coating was more effective than the silver nanoparticles or their combination against Staphylococcus aureus. All tested coatings were non-cytotoxic for eukaryotic cells.

JTD Keywords: antimicrobial peptide, biomaterials, bone, coatings, performance, ph, resistance, silanization, silver nanoparticles, staphylococcus aureus, Antimicrobial peptide, Reduces bacterial adhesion, Silanization, Silver nanoparticles, Staphylococcus aureus, Titanium functionalization

De Matteis, V, Griego, A, Scarpa, E, Cascione, M, Singh, J, Rizzello, L, (2023). Size Effect of Silver Nanoparticles Derived from Olive Mill Wastewater in THP-1 Cell Lines Applied Sciences-Basel 13, 6033

The constant demand of silver nanoparticles (AgNPs) for different applications requires a new selection of solvents and reagents for their synthesis, to make them less toxic to living organisms and the environment. Among the alternative technologies that can be used to exclude the use of toxic products, green chemistry is based on the employment of biomolecules derived from plants or microorganisms to achieve NPs. Therefore, with the aim of applying the principles of circular economy, the waste deriving from the production of olive oil represents a useful source of polyphenols to be used as reduction agents to obtain AgNPs. In our work, we employed the Olive Mill Wastewater (OMWW), the so-called vegetation water typical of the Mediterranean geographical area, to achieve two sizes of AgNPs, i.e., 50 nm and 30 nm. These NPs were tested on the human monocytic cell line (THP-1) using two concentrations (3 µM and 5 µM) to understand their ability to trigger or not the inflammatory response. This was undertaken following IL-6, IL-8, IL-5 and TNF-α secretion and the NF-kB translocation. We concluded that the AgNPs did not induce strong activation of these pathways, especially when the cells were treated with higher dimensional NPs. Consequently, the application of these NPs in vivo for therapeutic purpose could be significant.

JTD Keywords: agricultural waste, immune response, physicochemical properties, Green synthesis, Silver nanoparticles

Rodríguez-Contreras, A, Torres, D, Piñera-Avellaneda, D, Pérez-Palou, L, Ortiz-Hernández, M, Ginebra, MP, Calero, JA, Manero, JM, Rupérez, E, (2023). Dual-Action Effect of Gallium and Silver Providing Osseointegration and Antibacterial Properties to Calcium Titanate Coatings on Porous Titanium Implants International Journal Of Molecular Sciences 24, 8762

Previously, functional coatings on 3D-printed titanium implants were developed to improve their biointegration by separately incorporating Ga and Ag on the biomaterial surface. Now, a thermochemical treatment modification is proposed to study the effect of their simultaneous incorporation. Different concentrations of AgNO3 and Ga(NO3)3 are evaluated, and the obtained surfaces are completely characterized. Ion release, cytotoxicity, and bioactivity studies complement the characterization. The provided antibacterial effect of the surfaces is analyzed, and cell response is assessed by the study of SaOS-2 cell adhesion, proliferation, and differentiation. The Ti surface doping is confirmed by the formation of Ga-containing Ca titanates and nanoparticles of metallic Ag within the titanate coating. The surfaces generated with all combinations of AgNO3 and Ga(NO3)3 concentrations show bioactivity. The bacterial assay confirms a strong bactericidal impact achieved by the effect of both Ga and Ag present on the surface, especially for Pseudomonas aeruginosa, one of the main pathogens involved in orthopedic implant failures. SaOS-2 cells adhere and proliferate on the Ga/Ag-doped Ti surfaces, and the presence of gallium favors cell differentiation. The dual effect of both metallic agents doping the titanium surface provides bioactivity while protecting the biomaterial from the most frequent pathogens in implantology.

JTD Keywords: 3d-printing, agent, antibacterial activity, bioactive ti, biomaterials, coatings, competition, cu, gallium, glasses, ions, metal, porous structures, promote osseointegration, silver, titanium implants, In-vitro, Porous structures, Titanium implants

Piñera-Avellanedaa, D, Buxadera-Palomero, J, Ginebraa, MP, Calero, JA, Manero, JM, Rupérez, E, (2023). Surface competition between osteoblasts and bacteria on silver-doped bioactive titanium implant Biomaterials Advances 146, 213311

The rapid integration in the bone tissue and the prevention of bacterial infection are key for the success of the implant. In this regard, a silver (Ag)-doped thermochemical treatment that generate an Ag-doped calcium titanate layer on titanium (Ti) implants was previously developed by our group to improve the bone-bonding ability and provide antibacterial activity. In the present study, the biological and antibacterial potential of this coating has been further studied. In order to prove that the Ag-doped layer has an antibacterial effect with no detrimental effect on the bone cells, the behavior of osteoblast-like cells in terms of cell adhesion, morphology, proliferation and differentiation was evaluated, and the biofilm inhibition capacity was assessed. Moreover, the competition by the surface between cell and bacteria was carried out in two different co-culture methods. Finally, the treatment was applied to porous Ti implants to study in vivo osteointegration. The results show that the incorporation of Ag inhibits the biofilm formation and has no effect on the performance of osteoblast-like cells. Therefore, it can be concluded that the Ag-doped surface is capable of preventing bone bacterial infection and providing suitable osseointegration.Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.

JTD Keywords: co-culture, in vivo, porous titanium, silver, Co-culture, In vivo, Porous titanium, Silver, Titanium implant

De Matteis, V, Rizzello, L, Cascione, M, Pellegrino, P, Singh, J, Manno, D, Rinaldi, R, (2022). Sustainable Synthesis of FITC Chitosan-Capped Gold Nanoparticles for Biomedical Applications Clean Technologies 4, 942-953

The quest for novel nanoscale materials for different applications necessitates that they are easy to obtain and have excellent physical properties and low toxicity. Moreover, considering the ongoing environmental impact of noxious chemical waste products, it is important to adopt eco-friendly approaches for nanoparticle synthesis. In this work, a natural polymer (medium molecular weight chitosan) derived from chitin was employed as a reducing agent to obtain gold nanoparticles (AuNPs) with a chitosan shell (AuNPs@CS) by a microwave oven. The chitosan is economically viable and cost-competitive in the market showing also nontoxic behavior in the environment and living organisms. The synthesized AuNPs@CS-FITC NPs were fully characterized by spectroscopic and microscopic characterization techniques. The size distribution of NPs was about 15 nm, which is a suitable dimension to use in biomedical applications due to their high tissue penetration, great circulation in blood, and optimal clearance as well as low toxicity. The prepared polymer-capped NPs were further functionalized with a fluorescent molecule, i.e., Fluorescein-5-isothiocyanate (FITC), to perform imaging in the cell. The results highlighted the goodness of the synthesis procedure, as well as the high internalization rate that resulted in an optimal fluorescence intensity. Thus, this work presents a good sustainable/green approach-mediated polymer nanocomposite for various applications in the field of diagnostic imaging.

JTD Keywords: Agent, Biomedical, Fluorescent, Gold nanoparticles, Green synthesis, Nanomaterials, Silver nanoparticles

Iglesias-Fernandez, M, Buxadera-Palomero, J, Sadowska, JM, Espanol, M, Ginebra, MP, (2022). Implementation of bactericidal topographies on biomimetic calcium phosphates and the potential effect of its reactivity Biomaterials Advances 136, 212797

Since the discovery that nanostructured surfaces were able to kill bacteria, many works have been published focusing on the design of nanopatterned surfaces with antimicrobial properties. Synthetic bone grafts, based on calcium phosphate (CaP) formulations, can greatly benefit from this discovery if adequate nanotopographies can be developed. However, CaP are reactive materials and experience ionic exchanges when placed into aqueous solutions which may in turn affect cell behaviour and complicate the interpretation of the bactericidal results. The present study explores the bactericidal potential of two nanopillared CaP prepared by hydrolysis of two different sizes of alpha-tricalcium phosphate (alpha-TCP) powders under biomimetic or hydrothermal conditions. A more lethal bactericidal response toward Pseudomonas aeruginosa (similar to 75% killing efficiency of adhered bacteria) was obtained from the hydrothermally treated CaP which consisted in a more irregular topography in terms of pillar size (radius: 20-60 nm), interpillar distances (100-1500 nm) and pillar distribution (pillar groups forming bouquets) than the biomimetically treated one (radius: 20-40 nm and interpillar distances: 50-200 nm with a homogeneous pillar distribution). The material reactivity was greatly influenced by the type of medium (nutrient-rich versus nutrient-free) and the presence or not of bacteria. A lower reactivity and superior bacterial attachment were observed in the nutrient-free medium while a lower attachment was observed for the nutrient rich medium which was explained by a superior reactivity of the material paired with the lower tendency of planktonic bacteria to adhere on surfaces in the presence of nutrients. Importantly, the ionic exchanges produced by the presence of materials were not toxic to planktonic cells. Thus, we can conclude that topography was the main contributor to mortality in the bacterial adhesion tests.

JTD Keywords: bactericidal, calcium deficient hydroxyapatite, calcium phosphates, nanopillars, pseudomonas aeruginosa, reactivity, Adhesion, Antibacterial, Bactericidal, Biomaterials, Calcium deficient hydroxyapatite, Calcium phosphates, Hydroxyapatite, In-vitro, Infections, Nanopillars, Pseudomonas aeruginosa, Pseudomonas-aeruginosa, Reactivity, Recent progress, Silver, Topography, Transmission

López-Ortiz, M, Zamora, RA, Giannotti, MI, Hu, C, Croce, R, Gorostiza, P, (2022). Distance and Potential Dependence of Charge Transport Through the Reaction Center of Individual Photosynthetic Complexes Small 18, 2104366

Charge separation and transport through the reaction center of photosystem I (PSI) is an essential part of the photosynthetic electron transport chain. A strategy is developed to immobilize and orient PSI complexes on gold electrodes allowing to probe the complex's electron acceptor side, the chlorophyll special pair P700. Electrochemical scanning tunneling microscopy (ECSTM) imaging and current-distance spectroscopy of single protein complex shows lateral size in agreement with its known dimensions, and a PSI apparent height that depends on the probe potential revealing a gating effect in protein conductance. In current-distance spectroscopy, it is observed that the distance-decay constant of the current between PSI and the ECSTM probe depends on the sample and probe electrode potentials. The longest charge exchange distance (lowest distance-decay constant ?) is observed at sample potential 0 mV/SSC (SSC: reference electrode silver/silver chloride) and probe potential 400 mV/SSC. These potentials correspond to hole injection into an electronic state that is available in the absence of illumination. It is proposed that a pair of tryptophan residues located at the interface between P700 and the solution and known to support the hydrophobic recognition of the PSI redox partner plastocyanin, may have an additional role as hole exchange mediator in charge transport through PSI.© 2021 Wiley-VCH GmbH.

JTD Keywords: azurin, current distance decay spectroscopy, cytochrome c(6), electrochemical scanning tunneling microscopy (ecstm), electrochemistry, photosystem i, photosystem-i, plastocyanin, protein electron transfer, recognition, single metalloprotein, single molecules, structural basis, tunneling spectroscopy, 'current, Amino acids, Charge transfer, Chlorine compounds, Current distance decay spectroscopy, Decay spectroscopies, Distance decay, Electrochemical scanning tunneling microscopy, Electrochemical scanning tunneling microscopy (ecstm), Electrodes, Electron transfer, Electron transport properties, Gold compounds, Photosystem i, Photosystems, Protein electron transfer, Protein electron-transfer, Proteins, Scanning tunneling microscopy, Silver halides, Single molecule, Single molecules

Cascione, M, Rizzello, L, Manno, D, Serra, A, De Matteis, V, (2022). Green Silver Nanoparticles Promote Inflammation Shutdown in Human Leukemic Monocytes Materials (Basel) 15, 775

The use of silver nanoparticles (Ag NPs) in the biomedical field deserves a mindful analysis of the possible inflammatory response which could limit their use in the clinic. Despite the anti-cancer properties of Ag NPs having been widely demonstrated, there are still few studies concerning their involvement in the activation of specific inflammatory pathways. The inflammatory outcome depends on the synthetic route used in the NPs production, in which toxic reagents are employed. In this work, we compared two types of Ag NPs, obtained by two different chemical routes: conventional synthesis using sodium citrate and a green protocol based on leaf extracts as a source of reduction and capping agents. A careful physicochemical characterization was carried out showing spherical and stable Ag NPs with an average size between 20 nm and 35 nm for conventional and green Ag NPs respectively. Then, we evaluated their ability to induce the activation of inflammation in Human Leukemic Monocytes (THP-1) differentiated into M0 macrophages using 1 µM and 2 µM NPs concentrations (corresponded to 0.1 µg/mL and 0.2 µg/mL respectively) and two-time points (24 h and 48 h). Our results showed a clear difference in Nuclear Factor ?B (NF-?b) activation, Interleukins 6–8 (IL-6, IL-8) secretion, Tumor Necrosis Factor-? (TNF-?) and Cyclooxygenase-2 (COX-2) expression exerted by the two kinds of Ag NPs. Green Ag NPs were definitely tolerated by macrophages compared to conventional Ag NPs which induced the activation of all the factors mentioned above. Subsequently, the exposure of breast cancer cell line (MCF-7) to the green Ag NPs showed that they exhibited antitumor activity like the conventional ones, but surprisingly, using the MCF-10A line (not tumoral breast cells) the green Ag NPs did not cause a significant decrease in cell viability. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

JTD Keywords: activation, biosynthesis, gold nanoparticles, green route, inflammation response, mechanism, metal, nanotechnology, physico-chemical properties, raman-spectroscopy, resonance, silver nanoparticles, surface, Biomedical fields, Cell culture, Cell death, Chemical activation, Chemical routes, Conventional synthesis, Diseases, Green route, Inflammation response, Inflammatory response, Macrophages, Metal nanoparticles, Nf-kappa-b, Pathology, Physico-chemical properties, Physicochemical property, Property, Silver nanoparticles, Sodium compounds, Synthetic routes, Toxic reagents

Pérez-Rafael, S, Ivanova, K, Stefanov, I, Puiggalí, J, del Valle, LJ, Todorova, K, Dimitrov, P, Hinojosa-Caballero, D, Tzanov, T, (2021). Nanoparticle-driven self-assembling injectable hydrogels provide a multi-factorial approach for chronic wound treatment Acta Biomaterialia 134, 131-143

Chronic wounds represent a major health burden and drain on medical system. Efficient wound repair is only possible if the dressing materials target simultaneously multiple factors involved in wound chronicity, such as deleterious proteolytic and oxidative enzymes and high bacterial load. Here we develop multifunctional hydrogels for chronic wound management through self-assembling of thiolated hyaluronic acid (HA-SH) and bioactive silver-lignin nanoparticles (Ag@Lig NPs). Dynamic and reversible interactions between the polymer and Ag@Lig NPs yield hybrid nanocomposite hydrogels with shear-thinning and self-healing properties, coupled to zero-order kinetics release of antimicrobial silver in response to infection-related hyalurodinase. The hydrogels inhibit the major enzymes myeloperoxidase and matrix metalloproteinases responsible for wound chronicity in a patient's wound exudate. Furthermore, the lignin-capped AgNPs provide the hydrogel with antioxidant properties and strong antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. The nanocomposite hydrogels are not toxic to human keratinocytes after 7 days of direct contact. Complete tissue remodeling and restoration of skin integrity is demonstrated in vivo in a diabetic mouse model. Hematological analysis reveals lack of wound inflammation due to bacterial infection or toxicity, confirming the potential of HA-SH/Ag@Lig NPs hydrogels for chronic wound management. Statement of significance: Multifunctional hydrogels are promising materials to promote healing of complex wounds. Herein, we report simple and versatile route to prepare biocompatible and multifunctional self-assembled hydrogels for efficient chronic wound treatment utilizing polymer-nanoparticle interactions. Hybrid silver-lignin nanoparticles (Ag@Lig NPs) played both: i) structural role, acting as crosslinking nodes in the hydrogel and endowing it with shear-thinning (ability to flow under applied shear stress) and self-healing properties, and ii) functional role, imparting strong antibacterial and antioxidant activity. Remarkably, the in situ self-assembling of thiolated hyaluronic acid and Ag@Lig NPs yields nanocomposite hydrogels able to simultaneously inhibits the major factors involved in wound chronicity, namely the overexpressed deleterious proteolytic and oxidative enzymes, and high bacterial load.

JTD Keywords: catechol, chronic wounds, dressing materials, inhibition, mechanism, nano-enabled hydrogels, polyphenols, promogran, self-assembling, silver-lignin nanoparticles, systems, tannins, Chronic wounds, Degradation, Dressing materials, Nano-enabled hydrogels, Self-assembling, Silver-lignin nanoparticles, Thiolated hyaluronic acid

Rodríguez-Contreras, A, Torres, D, Rafik, B, Ortiz-Hernandez, M, Ginebra, MP, Calero, JA, Manero, JM, Ruperez, E, (2021). Bioactivity and antibacterial properties of calcium- and silver-doped coatings on 3D printed titanium scaffolds Surface & Coatings Technology 421, 127476

One of the major problems faced by metallic implants is the high probability of bacterial infections, with significant consequences for the patient. In this work, a thermochemical treatment is proposed to obtain silver-doped calcium titanate coatings on the Ti surface to improve the bioactivity of porous 3D-printed Ti structures and simultaneously provide them with antibacterial properties. A complete characterization of the new coating, the study of the ion release and the analysis of its cytotoxicity were carried out together with evaluation of the natural apatite forming in simulated body fluid (SBF). Moreover, the antibacterial properties of the coatings were assessed against Pseudomona aeruginosa and Escherichia coli as gram-negative and Staphylococcus aureus and Staphylococcus epidermidis as gram-positive bacterial strains. Ag ions were integrated into the Ca titanate layer and Ag nanoparticles were formed within the entire 3D Ti surface. Ca and Ag ions were released from both porous and solid samples into the Hanks' solution for 48 h. The treated surfaces showed no cytotoxicity and an apatite layer precipitated on the entire porous surface when the samples were immersed in SBF. The release of Ag from the surface had a strong antibacterial effect and prevented bacterial adhesion and proliferation on the surface. Moreover, the nanostructured topography of the coating resulted also in a reduction of bacterial adhesion and proliferation, even in absence of Ag. In conclusion, the cost-effective approach here reported provided protection against the most predominant bacterial colonizers to the Ti porous implants, while maintaining their bioactivity.

JTD Keywords: 3d-printing, alkaline, antibacterial activity, arthroplasty, bacterial adhesion, biomaterials, generation, ions, nanoparticles, osseointegration, silver, surface-layer, titanium implants, toxicity, 3d-printing, Antibacterial activity, Biomaterials, Porous structures, Silver, Ti metal, Titanium implants

Balakrishnan, H, Millan-Solsona, R, Checa, M, Fabregas, R, Fumagalli, L, Gomila, G, (2021). Depth mapping of metallic nanowire polymer nanocomposites by scanning dielectric microscopy Nanoscale 13, 10116-10126

Polymer nanocomposite materials based on metallic nanowires are widely investigated as transparent and flexible electrodes or as stretchable conductors and dielectrics for biosensing. Here we show that Scanning Dielectric Microscopy (SDM) can map the depth distribution of metallic nanowires within the nanocomposites in a non-destructive way. This is achieved by a quantitative analysis of sub-surface electrostatic force microscopy measurements with finite-element numerical calculations. As an application we determined the three-dimensional spatial distribution of ?50 nm diameter silver nanowires in ?100 nm-250 nm thick gelatin films. The characterization is done both under dry ambient conditions, where gelatin shows a relatively low dielectric constant, ?r ? 5, and under humid ambient conditions, where its dielectric constant increases up to ?r ? 14. The present results show that SDM can be a valuable non-destructive subsurface characterization technique for nanowire-based nanocomposite materials, which can contribute to the optimization of these materials for applications in fields such as wearable electronics, solar cell technologies or printable electronics. © The Royal Society of Chemistry.

JTD Keywords: composite, constant, electrodes, mode, nanostructures, objects, progress, subsurface, tomography, Composite materials, Dielectric materials, Electric force microscopy, Electrostatic force, Force microscopy, Low dielectric constants, Nanocomposites, Numerical calculation, Polymer nanocomposite, Printable electronics, Scanning dielectric microscopy, Silver nanowires, Solar cell technology, Stretchable conductors, Subsurface characterizations, Transparent electrodes, Wearable technology

Moya-Andérico, L, Vukomanovic, M, Cendra, MD, Segura-Feliu, M, Gil, V, del Río, JA, Torrents, E, (2021). Utility of Galleria mellonella larvae for evaluating nanoparticle toxicology Chemosphere 266, 129235

© 2020 Elsevier Ltd The use of nanoparticles in consumer products is currently on the rise, so it is important to have reliable methods to predict any associated toxicity effects. Traditional in vitro assays fail to mimic true physiological responses of living organisms against nanoparticles whereas murine in vivo models are costly and ethically controversial. For these reasons, this study aimed to evaluate the efficacy of Galleria mellonella as an alternative, non-rodent in vivo model for examining nanoparticle toxicity. Silver, selenium, and functionalized gold nanoparticles were synthesized, and their toxicity was assessed in G. mellonella larvae. The degree of acute toxicity effects caused by each type of NP was efficiently detected by an array of indicators within the larvae: LD50 calculation, hemocyte proliferation, NP distribution, behavioral changes, and histological alterations. G. mellonella larvae are proposed as a nanotoxicological model that can be used as a bridge between in vitro and in vivo murine assays in order to obtain better predictions of NP toxicity.

JTD Keywords: cellular uptake, cytotoxicity, galleria mellonella, gold nanoparticles, hemocytes, nanoparticles, nanotoxicity, non-rodent in vivo model, non-rodent in vivo model, oxidative stress, selenium-compounds, silica nanoparticles, silver nanoparticles, toxicity, toxicity screening, vitro, Galleria mellonella, Hemocytes, In-vivo model, Nanoparticles, Nanotoxicity, Non-rodent in vivo model, Toxicity screening

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.

JTD 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

JTD 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.

JTD 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.

JTD 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.

JTD 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