Neocuproine-functionalized silica-coated magnetic nanoparticles for extraction of copper(II) from aqueous solution

Neocuproine has been covalently bound to silica-coated maghemite(c-Fe2O3) magnetic nanoparticles (MNPs) by a phenyl ether linkage. The resulting MNPs are able to remove Cu(II) from 12 ppm aqueous solution with an extraction efficiency of up to 99% at pH 2.

Effective separation of Am(III) and Eu(III) from HNO3 Q1 Q2 solutions using CyMe4-BTPhen-functionalized silica-coated magnetic nanoparticles

It has been shown that CyMe4-BTPhen-functionalized silica-coated maghemite (c-Fe2O3) magnetic nanoparticles (MNPs) are capable of quantitative separation of Am(III) from Eu(III) from HNO3 solutions. These MNPs also show a small but significant selectivity for Am(III) over Cm(III) with a separation factor of around 2 in 4 M HNO3. The water molecule in the cavity of the BTPhen may also play an important part in the selectivity.

Effective separation of Am(III) and Eu(III) from HNO3 solutions using CyMe4-BTPhen-functionalized silica-coated magnetic nanoparticles

It has been shown that CyMe4-BTPhen-functionalized silica-coated maghemite (c-Fe2O3) magnetic nanoparticles (MNPs) are capable of quantitative separation of Am(III) from Eu(III) from HNO3 solutions. These MNPs also show a small but significant selectivity for Am(III) over Cm(III) with a separation factor of around 2 in 4 M HNO3. The water molecule in the cavity of the BTPhen may also play an important part in the selectivity.

The effect of DMSA-functionalized magnetic nanoparticles on transendothelial migration of monocytes in the murine lung via a beta(2) integrin-dependent pathway

Magnetic nanoparticles surface-functionalized with meso-2,3-dimercaptosuccinic acid (MNPs-DMSA) constitute an innovative and promising approach for tissue- and cell-targeted delivery of therapeutic drugs in the lung. Transendothelial migration of leukocytes in the lung is a side effect of endovenous administration of MNPs-DMSA. Using cytologic and phenotypic analysis of murine bronchoalveolar lavage cells, we identified monocytes/macrophages as the main subpopulation of leukocytes involved in this process. Moreover, ultrastructural analysis revealed the presence of nanoparticles inside of numerous macrophages from bronchoalveolar lavage. MNPs-DMSA at concentrations as high as 1 X 10(15) nanoparticles/mL had no toxic effects on macrophages, as evidenced by 3-(4, 5-dimethylthiazolyi-2)-2,5-diphenyltetrazolium bromide (MTT) assay. Notably, MNPs-DMSA up-regulated the mRNA expression of E, L- and P-selectin and macrophage-1 antigen in the murine lung. Upregulation of these cell adhesion molecules was associated with an increased concentration of tumor necrosis factor-alpha in lung. Finally, the critical relevance of the beta(2) integrin-dependent pathway in leukocyte transmigration elicited by MNPs-DMSA was demonstrated by use of knockout mice. Our results characterize mechanisms of the pro-inflammatory effects of MNPs-DMSA in the lung, and identify beta(2) integrin-targeted interventions as promising strategies to reduce pulmonary side effects of MNPs-DMSA during biomedical applications. (C) 2009 Elsevier Ltd. All rights reserved.

A single-step procedure for the preparation of palladium nanoparticles and a phosphine-functionalized support as catalyst for Suzuki cross-coupling reactions

We here report the preparation of supported palladium nanoparticles (NPs) stabilized by pendant phosphine groups by reacting a palladium complex containing the ligand 2-(diphenylphosphino)benzaldehyde with an amino-functionalized silica surface The Pd nanocatalyst is active for Suzuki cross-coupling reaction avoiding any addition of other sources of phosphine ligands The Pd intermediates and Pd NPs were characterized by solid-state nuclear magnetic resonance and transmission electron microscopy techniques The synthetic method was also applied to prepare magnetically recoverable Pd NPs leading to a catalyst that could be reused for up to 10 recycles In summary we gathered the advantages of heterogeneous catalysis magnetic separation and enhanced catalytic activity of palladium promoted by phosphine ligands to synthesize a new catalyst for Suzuki cross-coupling reactions The Pd NP catalyst prepared on the phosphine-functionalized support was more active and selective than a similar Pd NP catalyst prepared on an amino-functionalized support (C) 2010 Elsevier Inc All rights reserved

Enzyme immobilization on Ag nanoparticles/polyaniline nanocomposites

We show a simple strategy to obtain all efficient enzymatic broelectrochemical device, in which urease was immobilized oil electroactive nanostructured membranes (ENMs) made with polyaniline and silver nanoparticles (AgNP) stabilized in polyvinyl alcohol (PAni/PVA-AgNP). Fabrication of the modified electrodes comprised the chemical deposition of polyaniline followed by drop-coating of PVA-AgNP and urease, resulting in a final ITO/PAni/PVA-AgNP/urease electrode Configuration. For comparison. the electrochemical performance of ITO/PAni/urease electrodes (without Ag nanoparticles) was also studied. The performance of the modified electrodes toward Urea hydrolysis was investigated via amperometric measurements, revealing a fast increase in cathodic current with a well-defined peak upon addition of urea to the electrolytic solution. The cathodic currents for the ITO/PAni/PVA-AgNP urease electrodes were significantly higher than for the ITO/PAni/urease electrodes. The friendly environment provided by the ITO/PAni/PVA-AgNP electrode to the immobilized enzyme promoted efficient catalytic conversion of urea into ammonium and bicarbonate tons. Using the Michaelis-Menten kinetics equation, a K(M)(aPP) of 2.7 mmol L(-1) was obtained. indicating that the electrode architecture employed may be advantageous for fabrication of enzymatic devices with improved biocatalytic properties. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.

Enantioselective transesterification catalysis by Candida antarctica lipase immobilized on superparamagnetic nanoparticles

Lipase B from Candida antarctica can be directly immobilized onto functionalized superparamagnetic nanoparticles, preserving its enzymatic activity in the enantioselective transesterification of secondary alcohols, with excellent results in terms of enantiomeric discrimination. The immobilized enzyme can be easily recovered with a magnet, allowing its reuse with negligible loss of activity. (C) 2009 Elsevier Ltd. All rights reserved

Biolabeling with nanoparticles based on Y(2)O(3):Nd(3+) and luminescence detection in the near-infrared

Neodymium based fluorescence presents several advantages in comparison to conventional rare earth or enzyme-substrate based fluorescence emitting sources (e.g.Tb, HRP). Based on this fact we have herein explored a Nd-based fluoroimmunoassay. We efficiently detected the presence of an oxidized low-density lipoprotein (oxLDL) in human plasma a well-known marker for cardiovascular diseases, which causes around 30% of deaths worldwide. Conventional fluoroimmunoassay uses time-resolved luminescence techniques, with detection in the visible range, to eliminate the fluorescence background from the biological specimens. By using an immunoassay based on functionalized Y(2)O(3):Nd(3+) nanoparticles, where the excitation and emission processes in the Nd(3+) ion occur in the near-infrared (NIR) region, we have succeeded in eliminating the interferences from the biological fluorescence background, avoiding the use of time-resolved techniques. This yields higher emission intensity from the Nd(3+)-nanolabels and efficient detection of anti-oxidized low-density lipoproteins (anti-oxLDL) by Y(2)O(3):Nd(3+)-antibody-antigen conjugation, leading to a novel biolabeling method. (C) 2010 Elsevier B.V. All rights reserved.

SnO2 nanoparticles functionalized in amorphous silica and glass

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Magnetic nanohydrometallurgy: A promising nanotechnological approach for metal production and recovery using functionalized superparamagnetic nanoparticles

We report on a new, promising nanotechnological approach for hydrometallurgy based on recyclable, chemically functionalized superparamagnetic nanoparticles. In this process, the metal ions (e.g. Cu2+) are captured by the nanoparticles and confined at the electrode surface by means of an external magnet. Due to the pre-concentration effect the electrodeposition process is greatly improved, yielding the pure metal in a much shorter time in comparison with the conventional electrodeposition process. After the electrolysis, the magnetic nanoparticles are ready to return to the process. The proposed strategy can advantageously be incorporated in hydrometallurgy, reducing the number of steps associated with complexation, organic solvent extraction, metal release and diffusional electroprocessing, leading to a more sustainable technology. (C) 2012 Elsevier B.V. All rights reserved.

Functionalized surfaces and surface functionalization of nanomaterials

Nature leads, we follow. But nanotechnologists are in hot pursuit, in designing controllable structures that can mimic naturally occurring and artificially synthesized materials on a common platform. The supramolecular chemistry concerns the investigation of nature principles to produce fascinating complexed and functional molecular assemblies, as well as the utilization of these principles to generate novel devices and materials, potentially useful for sensing, catalysis, transport and other applications in medical or engineering science. The work presented in this thesis is a compilation of different synthetic methods to achieve inorganic-organic hybrid nanomaterials. Silicatein, a protein enzyme, which acts both as a catalyst and template for the formation of silica needles in marine sponges, has been used for the biosynthesis of semiconductor metal oxides on surfaces. Silicatein was immobilized on gold (111) surfaces using alkane thiol, as well as on a novel self-assembly of NTA on top of a “cushion” of reactive ester polymer has been successfully employed to make functionalised surfaces. The immobilization of silicatein on surfaces was monitored by surface plasmon spectroscopy, atomic force microscopy and confocal laser scanning microscopy. Surface bound silicatein retains its biocatalytic activity, which was demonstrated by monitoring its hydrocatalytic activity to catalyse the synthesis of biosilica, biotitania, and biozirconia. The synthesis of semiconductor metal oxides was characterized using scanning electron microscopy. This hydrolytic biocatalyst is used to synthesize the gold nanoparticles. The gold nanoparticles are formed by reduction of tetrachloroaurate, AuCl4-, by the action of sulfhydryl groups hidden below the surface groups of the protein. The resulting gold nanoparticles which are stabilized by surface bound silicatein further aggregate to form Au nanocrystals. The shape of the nanocrystals obtained by using recombinant silicatein is controlled through chiral induction by the protein during the nucleation of the nanocrystals. As an extension of this work, TiO2 nanowires were functionalized using polymeric ligand which incorporates the nitrilotriacetic acid (NTA) linker in the back bone to immobilize His-tagged silicatein onto the TiO2 nanowires. The surface bound protein not only retains its original hydrolytic properties, but also acts as a reductant for AuCl4- in the synthesis of hybrid TiO2/silicatein/Au nanocomposites. Functionalized, monocrystalline rutile TiO2 nanorods were prepared from TiCl4 in aqueous solution in the presence of dopamine. The surface bound organic ligand controls the morphology as well as the crystallinity and the phase selection of TiO2. The surface amine groups can be tailored further with functional molecules such as dyes. As an example, this surface functionality is used for the covalent binding of a fluorescent dye,4-chloro-7- nitrobenzylurazene (NBD) to the TiO2 nanorods. The polymeric ligands have been used successfully for the in-situ and post-functionalization of TiO2 nanoparticles. Besides to chelating dopamine anchor group the multifunctional ligand system presented here incorporates a modifier molecule which allows the binding of functional molecules (here the dyes pyrene, NBD, and Texas Red) as well as additional entities which allow tailoring the solubility of inorganic nanocrystals in different solvents. A novel method for the surface functionalization of fullerene-type MoS2 nanoparticles and subsequently binding these nanoparticles onto TiO2 nanowires has been reported using polymeric ligands. The procedure involves the complexation of IF-MoS2 with a combination of Ni2+ via an umbrella-type nitrilotriacetic acid (NTA) and anchoring them to the sidewalls of TiO2 nanowires utilizing the hydroxyl groups of dopamine present in the main contents of polymeric ligand. A convenient method for the synthesis of Au/CdS nanocomposites has been presented, which were achieved through the novel method of thiol functionalization of gold colloids. The thermodynamically most stable phase of ZrO2 (cubic) has been obtained at much lower temperature (180°C). These nanoparticles are highly blue fluorescent, with a high surface area.

Light-sensitive polymeric nanoparticles based on photo-cleavable chromophores

Der Fokus dieser Arbeit liegt in dem Design, der Synthese und der Charakterisierung neuartiger photosensitiver Mikrogele und Nanopartikel als potentielle Materialien für Beladungs- und Freisetzungsanwendungen. Zur Realisierung dieses Konzepts wurden verschiedene Ansätze untersucht.Es wurden neuartige niedermolekulare lichtspaltbare Vernetzermoleküle auf der Basis von o-Nitrobenzylderivaten synthetisiert, charakterisiert und zur Herstellung von photosensitiven PMMA und PHEMA Mikrogelen verwendet. Diese sind unter Bestrahlung in organischen Lösungsmitteln quellbar und zersetzbar. Durch die Einführung anionischer MAA Gruppen in solche PHEMA Mikrogele wurde dieses Konzept auf doppelt stimuliresponsive p(HEMA-co-MAA) Mikrogele erweitert. Hierbei wurde ein pH-abhängiges Quellbarkeitsprofil mit der lichtinduzierten Netzwerkspaltung in wässrigen Medien kombiniert. Diese duale Sensitivität zu zwei zueinander orthogonalen Reizen stellt ein vielversprechendes Konzept zur Kombination einer pH-abhängigen Beladung mit einer lichtinduzierten Freisetzung von funktionellen Substanzen dar. Desweiteren wurden PAAm Mikrogele entwickelt, welche sowohl eine Sensitivität gegenüber Enzymen als auch Licht aufweisen. Dieses Verhalten wurde durch die Verwendung von (meth-)acrylatfunktionalisierten Dextranen als polymere Vernetzungsmoleküle erreicht. Das entsprechende stimuliresponsive Profil basiert auf der enzymatischen Zersetzbarkeit der Polysaccharid-Hauptkette und der Anbindung der polymerisierbaren Vinyleinheiten an diese über photospaltbare Gruppen. Die gute Wasserlöslichkeit der Vernetzermoleküle stellt einen vielversprechenden Ansatz zur Beladung solcher Mikrogele mit funktionellen hydrophilen Substanzen bereits während der Partikelsynthese dar. Ein weiteres Konzept zur Beladung von Mikrogelen basiert auf der Verwendung von photolabilen Wirkstoff-Mikrogel Konjugaten. In einem ersten Schritt zur Realisierung solch eines Ansatzes wurde ein neuartiges Monomer entwickelt. Hierbei wurde Doxorubicin über eine lichtspaltbare Gruppe an eine polymerisierbare Methacrylatgruppe angebunden. Für die Freisetzung hydrophober Substanzen in wässrigen Medien wurden polymere Photolack-Nanopartikel entwickelt, welche sich unter Bestrahlung in Wasser zersetzen. Die lichtinduzierte Änderung der Hydrophobizität des Polymers ermöglichte die Freisetzung von Nilrot durch das Auflösen der partikulären Struktur. Ein interessanter Ansatz zur Verhinderung einer unkontrollierten Freisetzung funktioneller Substanzen aus Mikrogelen ist die Einführung einer stimuliresponsiven Schale. In diesem Kontext wurden Untersuchungen zur Bildung von nicht-stimulisensitiven Schalen um vorgefertigte Mikrogelkerne und zur Synthese von Hydrogelkernen in vorgefertigten polymeren Schalen (Nanokapseln) durchgeführt.

Immobilization and characterization of recombinant esterase enzyme on chitosan nanoparticles

Immobilization of biologically important molecules on myriad nano-sized materials has attracted great attention. Through this study, thermophilic esterase enzyme was obtained using recombinant DNA technology and purified applying one-step His-Select HF nickel affinity gel. The synthesis of chitosan was achieved from chitin by deacetylation process and degree of deacetylation was calculated as 89% by elemental analysis. Chitosan nanoparticles were prepared based on the ionic gelation of chitosan with tripolyphosphate anions. The physicochemical properties of the chitosan and chitosan nanoparticles were determined by several methods including SEM (Scanning Electron Microscopy), FT-IR (Fourier Transform Infrared Spectroscopy) and DLS (Dynamic Light Scattering). The morphology of chitosan nanoparticles was spherical and the nanospheres’ average diameter was 75.3 nm. The purified recombinant esterase was immobilized efficiently by physical adsorption onto chitosan nanoparticles and effects of various immobilization conditions were investigated in details to develope highly cost-effective esterase as a biocatalyst to be utilized in biotechnological purposes. The optimal conditions of immobilization were determined as follows; 1.0 mg/mL of recombinant esterase was immobilized on 1.5 mg chitosan nanoparticles for 30 min at 60°C, pH 7.0 under 100 rpm stirring speed. Under optimized conditions, immobilized recombinant esterase activity yield was 88.5%. The physicochemical characterization of enzyme immobilized chitosan nanoparticles was analyzed by SEM, FT-IR and AFM (Atomic Force Microscopy).

Multiscale Characterization of Acrylic Bone Cement Modified with Functionalized Mesoporous Silica Nanoparticles

Acrylic bone cement is widely used to anchor orthopedic implants to bone and mechanical failure of the cement mantle surrounding an implant can contribute to aseptic loosening. In an effort to enhance the mechanical properties of bone cement, a variety of nanoparticles and fibers can be incorporated into the cement matrix. Mesoporous silica nanoparticles (MSNs) are a class of particles that display high potential for use as reinforcement within bone cement. Therefore, the purpose of this study was to quantify the impact of modifying an acrylic cement with various low-loadings of mesoporous silica. Three types of MSNs (one plain variety and two modified with functional groups) at two loading ratios (0.1 and 0.2 wt/wt) were incorporated into a commercially available bone cement. The mechanical properties were characterized using four-point bending, microindentation and nanoindentation (static, stress relaxation, and creep) while material properties were assessed through dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, FTIR spectroscopy, and scanning electron microscopy. Four-point flexural testing and nanoindentation revealed minimal impact on the properties of the cements, except for several changes in the nano-level static mechanical properties. Conversely, microindentation testing demonstrated that the addition of MSNs significantly increased the microhardness. The stress relaxation and creep properties of the cements measured with nanoindentation displayed no effect resulting from the addition of MSNs. The measured material properties were consistent among all cements. Analysis of scanning electron micrographs images revealed that surface functionalization enhanced particle dispersion within the cement matrix and resulted in fewer particle agglomerates. These results suggest that the loading ratios of mesoporous silica used in this study were not an effective reinforcement material. Future work should be conducted to determine the impact of higher MSN loading ratios and alternative functional groups. (C) 2014 Elsevier Ltd. All rights reserved.