Synthesis of Citrate-Stabilized Silver Nanoparticles Modified by Thermal and pH Preconditioned Tannic Acid.

Silver nanoparticles (AgNPs) may be synthesized by many different methods, with those based on the thermal reduction of silver salts by citric acid or citric acid/tannic acid being amongst the most commonly used. These methods, although widely used and technically simple, can produce particles in which the size, polydispersivity and morphology can vary greatly. In this work nearly mono-dispersed spherical AgNPs have been synthesized via a one-step reduction method by using sodium citrate and varying quantities of Tannic Acid (TA), which was thermally conditioned prior to use in the growth process.

Rational design of multi-functional gold nanoparticles with controlled biomolecule adsorption: a multi-method approach for in-depth characterization.

Multi-functionalized nanoparticles are of great interest in biotechnology and biomedicine, especially for diagnostic and therapeutic purposes. However, at the moment the characterization of complex, multi-functional nanoparticles is still challenging and this hampers the development of advanced nanomaterials for biological applications. In this work, we have designed a model system consisting of gold nanoparticles functionalized with two differentially-terminated poly(ethylene oxide) ligands, providing both "stealth" properties and protein-binding capabilities to the nanoparticles.

Characterisation of nanomaterial hydrophobicity using engineered surfaces.

Characterisation of engineered nanomaterials (NMs) is of outmost importance for the assessment of the potential risks arising from their extensive use. NMs display indeed a large variety of physico-chemical properties that drastically affect their interaction with biological systems. Among them, hydrophobicity is an important property that is nevertheless only slightly covered by the current physico-chemical characterisation techniques.

Analytical ultracentrifugation for analysis of doxorubicin loaded liposomes.

Analytical ultracentrifugation (AUC) is a powerful tool for the study of particle size distributions and interactions with high accuracy and resolution. In this work, we show how the analysis of sedimentation velocity data from the AUC can be used to characterize nanocarrier drug delivery systems used in nanomedicine. Nanocarrier size distribution and the ratio of free versus nanoparticle-encapsulated drug in a commercially available liposomal doxorubicin formulation are determined using interference and absorbance based AUC measurements and compared with results generated with conventional techniques.

Bioinspired Rose-Petal-Like Substrates Generated by Electropolymerization on Micropatterned Gold Substrates.

Invited for this month's cover are the collaborating groups of Dr. Thierry Darmanin at Université Côte d'Azur, France and Dr. François Rossi at JRC European Commission, Italy.

Bioinspired Rose-Petal-Like Substrates Generated by Electropolymerization on Micropatterned Gold Substrates.

Surfaces with high water-adhesion properties are promising materials for different applications in the field of water treatment and management, such as for water-harvesting systems or oil/water separation membranes. Herein, we developed rose-petal-like substrates that demonstrate interesting parahydrophobic character. This bioinspired material mimics the natural substrate thanks to a combination of two fabrication steps: (1) micropatterning to create a microstructured gold-coated substrate consisting of square pillars and (2) an electropolymerization process generating nanostructures over the micropillars.

pH-sensitive niosomes: Effects on cytotoxicity and on inflammation and pain in murine models.

pH-sensitive nonionic surfactant vesicles (niosomes) by polysorbate-20 (Tween-20) or polysorbate-20 derivatized by glycine (added as pH sensitive agent), were developed to deliver Ibuprofen (IBU) and Lidocaine (LID). For the physical-chemical characterization of vesicles (mean size, size distribution, zeta potential, vesicle morphology, bilayer properties and stability) dynamic light scattering (DLS), small angle X-ray scattering and fluorescence studies were performed. Potential cytotoxicity was evaluated on immortalized human keratinocyte cells (HaCaT) and on immortalized mouse fibroblasts Balb/3T3.

Gold nanoparticles increases UV and thermal stability of human serum albumin.

Ultraviolet (UV) radiation, temperature, and time can degrade proteins. Here, the authors show that gold nanoparticles significantly protect human serum albumin from denaturation when exposed to "stressing" conditions such as UV irradiation and sustained exposure in suboptimal conditions. In particular, the authors show that gold nanoparticles significantly reduce the decrease in secondary structure induced by UV irradiation or extended exposure to ambient temperature.

Characterization of silver nanoparticles-alginate complexes by combined size separation and size measurement techniques.

The detection and quantification of nanoparticles is a complex issue due to the need to combine "classical" identification and quantification of the constituent material, with the accurate determination of the size of submicrometer objects, usually well below the optical diffraction limit. In this work, the authors show that one of the most used analytical methods for silver nanoparticles, asymmetric flow field-flow fractionation, can be strongly influenced by the presence of dissolved organic matter (such as alginate) and lead to potentially misleading results. The authors explain the anomalies in the separation process and show a very general way forward based on the combination of size separation and size measurement techniques.

Biofouling Properties of Nitroxide-Modified Amorphous Carbon Surfaces.

Amorphous carbon films exhibit attractive optical and surface properties. In this work, modified amorphous carbon films incorporating nitroxide groups (α-CNO) have been obtained by searching for a condensed analogue to classical soft antifouling materials. Thin films deposited by reactive magnetron sputtering in air discharges at varying power conditions were characterized by ellipsometry, atomic force microscopy, and water contact angle.

Modulating charge-dependent and folding-mediated antimicrobial interactions at peptide-lipid interfaces.

Peptide-lipid interactions support a variety of biological functions. Of particular interest are those that underpin fundamental mechanisms of innate immunity that are programmed in host defense or antimicrobial peptide sequences found virtually in all multicellular organisms. Here we synthetically modulate antimicrobial peptide-lipid interactions using an archetypal helical antimicrobial peptide and synthetic membranes mimicking bacterial and mammalian membranes in solution.

Multiplex cell microarrays for high-throughput screening.

Microarray technology was developed in the early 1990s to measure the transcription levels of thousands of genes in parallel. The basic premise of high-density arraying has since been expanded to create cell microarrays. Cells on chip are powerful experimental tools for high-throughput and multiplex screening of samples or cellular functions.

Toward achieving harmonization in a nano-cytotoxicity assay measurement through an interlaboratory comparison study.

Development of reliable cell-based nanotoxicology assays is important for evaluation of potentially hazardous engineered nanomaterials. Challenges to producing a reliable assay protocol include working with nanoparticle dispersions and living cell lines, and the potential for nano-related interference effects. Here we demonstrate the use of a 96-well plate design with several measurement controls and an interlaboratory comparison study involving five laboratories to characterize the robustness of a nanocytotoxicity MTS cell viability assay based on the A549 cell line.

Quantification of the cellular dose and characterization of nanoparticle transport during in vitro testing.

Background: The constant increase of the use of nanomaterials in consumer products is making increasingly urgent that standardized and reliable in vitro test methods for toxicity screening be made available to the scientific community. For this purpose, the determination of the cellular dose, i.e.

Surface Analysis of Gold Nanoparticles Functionalized with Thiol-Modified Glucose SAMs for Biosensor Applications.

In this work, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Principal Component Analysis (PCA) and X-ray Photoelectron Spectroscopy (XPS) have been used to characterize the surface chemistry of gold substrates before and after functionalization with thiol-modified glucose self-assembled monolayers and subsequent biochemical specific recognition of maltose binding protein (MBP). The results indicate that the surface functionalization is achieved both on flat and nanoparticles gold substrates thus showing the potential of the developed system as biodetection platform. Moreover, the method presented here has been found to be a sound and valid approach to characterize the surface chemistry of nanoparticles functionalized with large molecules.

Highly Flexible Platform for Tuning Surface Properties of Silica Nanoparticles and Monitoring Their Biological Interaction.

The following work presents a simple, reliable and scalable seeding-growth methodology to prepare silica nanoparticles (SiO2 NPs) (20, 30, 50 and 80 nm) directly in aqueous phase, both as plain- as well as fluorescent-labeled silica. The amount of fluorescent label per particle remained constant regardless of size, which facilitates measurements in terms of number-based concentrations. SiO2 NPs in dispersion were functionalized with an epoxysilane, thus providing a flexible platform for the covalent linkage of wide variety of molecules under mild experimental conditions.

A combined proteomics and metabolomics approach to assess the effects of gold nanoparticles in vitro.

Omics technologies, such as proteomics or metabolomics, have to date been applied in the field of nanomaterial safety assessment to a limited extent. To address this dearth, we developed an integrated approach combining the two techniques to study the effects of two sizes, 5 and 30 nm, of gold nanoparticles (AuNPs) in Caco-2 cells. We observed differences in cells exposed for 72 h to each size of AuNPs: 61 responsive (up/down-regulated) proteins were identified and 35 metabolites in the cell extract were tentatively annotated.

Review of achievements of the OECD Working Party on Manufactured Nanomaterials' Testing and Assessment Programme. From exploratory testing to test guidelines.

This paper charts the almost ten years of history of OECD's work on nanosafety, during which the programme of the OECD on the Testing and Assessment of Manufactured Nanomaterials covered the testing of eleven nanomaterials for about 59 end-points addressing physical-chemical properties, mammalian and environmental toxicity, environmental fate and material safety. An overview of the materials tested, the test methods applied and the discussions regarding the applicability of the OECD test guidelines, which are recognised methods for regulatory testing of chemicals, are given. The results indicate that many existing OECD test guidelines are suitable for nanomaterials and consequently, hazard data collected using such guidelines will fall under OECD's system of Mutual Acceptance of Data (MAD) which is a legally binding instrument to facilitate the international acceptance of information for the regulatory safety assessment of chemicals.

Role of the crystalline form of titanium dioxide nanoparticles: Rutile, and not anatase, induces toxic effects in Balb/3T3 mouse fibroblasts.

The wide use of titanium dioxide nanoparticles (TiO2 NPs) in industrial applications requires the investigation of their effects on human health. In this context, we investigated the effects of nanosized and bulk titania in two different crystalline forms (anatase and rutile) in vitro. By colony forming efficiency assay, a dose-dependent reduction of the clonogenic activity of Balb/3T3 mouse fibroblasts was detected in the presence of rutile, but not in the case of anatase NPs.

Dispersion Behaviour of Silica Nanoparticles in Biological Media and Its Influence on Cellular Uptake.

Given the increasing variety of manufactured nanomaterials, suitable, robust, standardized in vitro screening methods are needed to study the mechanisms by which they can interact with biological systems. The in vitro evaluation of interactions of nanoparticles (NPs) with living cells is challenging due to the complex behaviour of NPs, which may involve dissolution, aggregation, sedimentation and formation of a protein corona. These variable parameters have an influence on the surface properties and the stability of NPs in the biological environment and therefore also on the interaction of NPs with cells.

Application of Asymmetric Flow Field-Flow Fractionation hyphenations for liposome-antimicrobial peptide interaction.

Asymmetric Flow Field-Flow Fractionation (AF4) combined with multidetector analysis form a promising technique in the field of nanoparticle characterization. This system is able to measure the dimensions and physicochemical properties of nanoparticles with unprecedented accuracy and precision. Here, for the first time, this technique is optimized to characterize the interaction between an archetypal antimicrobial peptide and synthetic membranes.

Determination of the structure and morphology of gold nanoparticle-HSA protein complexes.

We propose a simple method to determine the structure and morphology of nanoparticle protein complexes. By combining a separation method with online size measurements, density measurements and circular dichroism, we could identify the number of proteins bound to each nanoparticle and their secondary structure changes in the complex. This method provides much-needed experimental information on the interaction of proteins with nanoparticles and on the behavior of nanoparticles in biological systems.

Cyto/hemocompatible magnetic hybrid nanoparticles (Ag2S-Fe3O4) with luminescence in the near-infrared region as promising theranostic materials.

Small hybrid nanoparticles composed of highly biocompatible Ag2S quantum dots (QD) emitting in the near-infrared region and superparamagnetic iron oxide (SPION) are produced in a simple extraction method utilizing ligand exchange mechanism. Hybrid nanoparticles luminesce at the same wavelength as the parent QD, therefore an array of hybrid nanoparticles with emission between 840 and 912nm were easily produced. Such hybrid structures have (1) strong luminescence in the medical imaging window eliminating the autofluoresence of cells as effective optical probes, (2) strong magnetic response for magnetic targeting and (3) good cyto/hemocompatibility.

Different mechanisms are involved in oxidative DNA damage and genotoxicity induction by ZnO and TiO2 nanoparticles in human colon carcinoma cells.

In this work we investigated the genotoxicity of zinc oxide and titanium dioxide nanoparticles (ZnO NPs; TiO2 NPs) induced by oxidative stress on human colon carcinoma cells (Caco-2 cells). We measured free radical production in acellular conditions by Electron Paramagnetic Resonance technique and genotoxicity by micronucleus and Comet assays. Oxidative DNA damage was assessed by modified Comet assay and by measuring 8-oxodG steady state levels.