Molecular beacon-decorated polymethylmethacrylate core-shell fluorescent nanoparticles for the detection of survivin mRNA in human cancer cells.

One of the main goals of nanomedicine in cancer is the development of effective drug delivery systems, primarily nanoparticles. Survivin, an overexpressed anti-apoptotic protein in cancer, represents a pharmacological target for therapy and a Molecular Beacon (MB) specific for survivin mRNA is available. In this study, the ability of polymethylmethacrylate nanoparticles (PMMA-NPs) to promote survivin MB uptake in human A549 cells was investigated. Fluorescent and positively charged core PMMA-NPs of nearly 60nm, obtained through an emulsion co-polymerization reaction, and the MB alone were evaluated in solution, for their analytical characterization; then, the MB specificity and functionality were verified after adsorption onto the PMMA-NPs. The carrier ability of PMMA-NPs in A549 was examined by confocal microscopy. With the optimized protocol, a hardly detectable fluorescent signal was obtained after incubation of the cells with the MB alone (fluorescent spots per cell of 1.90±0.40 with a mean area of 1.04±0.20µm2), while bright fluorescent spots inside the cells were evident by using the MB loaded onto the PMMA-NPs. (27.50±2.30 fluorescent spots per cell with a mean area of 2.35±0.16µm2). These results demonstrate the ability of the PMMA-NPs to promote the survivin-MB internalization, suggesting that this complex might represent a promising strategy for intracellular sensing and for the reduction of cancer cell proliferation

Cell Volume Regulation Mechanisms in Differentiated Astrocytes

The ability of astrocytes to control extracellular volume homeostasis is critical for brain function and pathology. Uncovering the mechanisms of cell volume regulation by astrocytes will be important for identifying novel therapeutic targets for neurological conditions, such as those characterized by imbalances to hydro saline challenges (as in edema) or by altered cell volume regulation (as in glioma). One major challenge in studying the astroglial membrane channels involved in volume homeostasis in cell culture model systems is that the expression patterns of these membrane channels do not resemble those observed in vivo. In our previous study, we demonstrated that rat primary astrocytes grown on nanostructured interfaces based on hydrotalcite-like compounds (HTlc) in vitro are differentiated and display molecular and functional properties of in vivo astrocytes, such as the functional expression of inwardly rectifying K+ channel (Kir 4.1) and Aquaporin-4 (AQP4) at the astrocytic microdomain. Here, we take advantage of the properties of differentiated primary astrocytes in vitro to provide an insight into the mechanism underpinning astrocytic cell volume regulation and its correlation with the expression and function of AQP4, Transient Receptor Potential Vanilloid 4 (TRPV4), and Volume Regulated Anion Channel (VRAC)

Effect of the Synthesis Route and Fe Presence on the Redox Activity of Ni in Layered Double Hydroxides

Pt electrodes coated with a Ni/Al or Ni/Fe layered double hydroxide (LDH) were studied to investigate whether the presence of Fe and the extent of crystallinity affect the performance of the Ni centers as redox mediators for oxidizable compounds. The LDHs were synthesized by both a chemical and an electrochemical method, which allowed the obtainment of thin and well-adherent LDH films having similar morphology but a different crystallinity degree. Fe centers were not electroactive but they influenced the electroactivity of Ni, shifting the redox potential to less anodic values and increasing the percentage of the electroactive Ni sites. The LDHs prepared by electrodeposition were more conductive than the chemically synthesized LDHs, and, when Fe was the trivalent metal, the electronic conductivity was further increased. The highest electrocatalytic efficiency, evaluated taking glucose as model compound, was obtained for the electrodes coated with the electrochemically synthesized LDHs

Keratin/Hydrotalcites Hybrid Sponges as Promising Adsorbents for Cationic and Anionic Dyes

In this work, keratin sponges were prepared by freeze-drying method and tested for adsorption of Azure A and Methyl Orange dyes. The obtained materials showed a porosity of 99.92% and a mean pore size dimension of about 91 μm. The use of oxidized sucrose with a heating treatment at 150°C was demonstrated to be a useful crosslinking procedure alternative to the conventional glutaraldehyde. Keratin sponges showed a maximum adsorption capacity of 0.063 and of 0.037 mmol/g for Azure A and Methyl Orange, respectively. The absorption of the cationic dye Azure A onto keratin sponges was better described by Freundlich model while the isotherm adsorption of the anionic Methyl Orange was found to correlate with both Langmuir and Freundlich models. The mean free energies evaluated by using the D-R model indicated a physisorption of Methyl Orange and a chemisorptions of Azure A onto keratin sponges. Finally, the functionalization of keratin sponges with Zn Al hydrotalcites nanoparticles did not affect the adsorption performances of the adsorbent toward the cationic dye Azure A, while it improved those toward the anionic Methyl Orange, increasing the related removal efficiencies from 43 to 96%. Collectively, the reported data indicates that the combination of keratin with hydrotalcites nanoparticles is a good strategy to obtain more functional adsorbent materials of potential interest for water treatment and purification

Selective internalization of ZnAl-HTlc nanoparticles in normal and tumor cells. A study of their potential use in cellular delivery

A colloidal dispersion of zinc aluminum hydrotalcite nanoparticles (ZnAl-HTlc) has been used for in vitro experimental procedures in order to provide reliable data on their potential application in cellular delivery. Two different cell lines (HeLa tumor cells and MDCK normal cells) with a similar epithelial derivation have been used. Sedimentation studies performed in the presence of different constituents of the cell culture medium revealed the importance of serum components to stabilize the colloidal dispersions of nanosized ZnAl-HTlc. Cell viability assay showed for nanosized ZnAl-HTlc a higher cell growth inhibition on tumor cells compared to normal cells whereas LDH test showed the absence of toxicity for both cell lines. Cellular uptake experiments indicated a preferential internalization of ZnAl-HTlc nanoparticles in HeLa tumor cells. Adsorption study and steady state fluorescence measurements on the phenol red/HTlc hybrid were carried out in order to verify the possibility of using phenol red as fluorescent dye for ZnAl-HTlc nanoparticles. The observed spectral behavior indicated a strong interaction between the dye and the inorganic matrix and the preferential adsorption of the dye on the nanoparticle surface has been confirmed by the XRPD data. Fluorescence confocal imaging showed a different localization pattern of nanosized HTlc in the two cell lines and a higher fluorescence signals in tumor cells supporting the occurrence of more efficient internalization processes in the pathogen cell line as observed in the cellular uptake experiments. © 2011 Elsevier B.V

Umbrella motion of the methyl cation, radical, and anion molecules

The main purpose of the present work is to characterize the umbrella inversion motion of the CH-3, CH3 and CH-3 molecules as a function of the environmental conditions. In particular, for the three investigated species we have studied how temperature affects times for umbrella inversion modes and their propagation velocity. These data are used to predict the statistical behavior of the reactions involving the AB3 like molecules and to relate the umbrella potential with the rate constants. The second aspect of this study concerns the molecular distribution charges as a function of the umbrella opening angle and of the total charge. The results have been used to calculate the induced electric field on a probe charge located at a given position perpendicular to the plane of the hydrogen atoms which is the most relevant for the reaction. Obtained values are presented as a function of the umbrella opening angle

Bioactive Keratin and Fibroin Nanoparticles: An Overview of Their Preparation Strategies

In recent years, several studies have focused their attention on the preparation of biocompatible and biodegradable nanocarriers of potential interest in the biomedical field, ranging from drug delivery systems to imaging and diagnosis. In this regard, natural biomolecules-such as proteins-represent an attractive alternative to synthetic polymers or inorganic materials, thanks to their numerous advantages, such as biocompatibility, biodegradability, and low immunogenicity. Among the most interesting proteins, keratin extracted from wool and feathers, as well as fibroin extracted from Bombyx mori cocoons, possess all of the abovementioned features required for biomedical applications. In the present review, we therefore aim to give an overview of the most important and efficient methodologies for obtaining drug-loaded keratin and fibroin nanoparticles, and of their potential for biomedical applications

Efficiency enhancement of P3HT:PCBM solar cells containing scattering Zn-Al hydrotalcite nanoparticles in the PEDOT:PSS layer

In this article we report on a new hybrid (organic-inorganic) composite material based on hydrophilic, electrically inert and semi-transparent hydrotalcite (HT) nanoparticles and a pHneutral formulation of PEDOT:PSS. The application of this composite material as electrically and optically active buffer layer in P3HT:PC61BM bulk heterojunction (BHJ) solar cells is reported. Two different synthetic routes are explored to obtain HTs having discoid shape, with a diameter of around 150- 200 nm and a thickness of ~20 nm, to be easily embedded in ~50 nm thick PEDOT:PSS films. The good affinity between HTs and the sulfonate groups of the PEDOT:PSS allows to obtain homogeneous HTs/PEDOT:PSS films, for HT concentrations of 0.25% and 0.50% by weight (vs. PEDOT:PSS). At these particle loads the electrical and morphological features of doped and undoped PEDOT:PSS films are nearly identical, while providing a significant effect on the visible light scattering properties of the composite films. We demonstrate ~12% improvement in power conversion efficiency (PCE) for P3HT:PC61BM solar cells incorporating HTs in the PEDOT: PSS layer, which mainly originates from increased shortcircuit current densities (JSC)