Nanocomposite Based on Functionalized Gold Nanoparticles and Sulfonated Poly(ether ether ketone) Membranes: Synthesis and Characterization.

Gold nanoparticles, capped by 3-mercapto propane sulfonate (Au-3MPS), were synthesized inside a swollen sulfonated poly(ether ether ketone) membrane (sPEEK). The formation of the Au-3MPS nanoparticles in the swollen sPEEK membrane was observed by spectroscopic and microscopic techniques. The nanocomposite containing the gold nanoparticles grown in the sPEEK membrane, showed the plasmon resonance λmax at about 520 nm, which remained stable over a testing period of three months. The size distribution of the nanoparticles was assessed, and the sPEEK membrane roughness, both before and after the synthesis of nanoparticles, was studied by AFM. The XPS measurements confirm Au-3MPS formation in the sPEEK membrane. Moreover, AFM experiments recorded in fluid allowed the production of images of the Au-3MPS@sPEEK composite in water at different pH levels, achieving a better understanding of the membrane behavior in a water environment; the dynamic hydration process of the Au-3MPS@sPEEK membrane was investigated. These preliminary results suggest that the newly developed nanocomposite membranes could be promising materials for fuel cell applications.

Functionalized gold nanoparticles for topical delivery of methotrexate for the possible treatment of psoriasis.

Gold nanoparticles (AuNPs) represent an effective choice for topical drug delivery systems thanks to their small size, general non-toxicity, ease of functionalization and high surface to volume ratio. Even if systemic, methotrexate still plays an important role in psoriasis treatment: its topical use shows insufficient percutaneus penetration owing to limited passive diffusion, high molecular weight and dissociation at physiological pH. The aim of our study was to design a new drug delivery nanocarrier for Methotrexate and to improve its solubility, stability and biodistribution. AuNPs were on purpose prepared with a hydrophilic stabilizing layer, in order to improve the colloidal stability in water. Water-soluble gold nanoparticles functionalized by sodium 3-mercapto-1-propansulfonate (Au-3MPS) were prepared and loaded with methotrexate (MTX). The loading efficiency of MTX on Au-3MPS was assessed in the range 70-80%, with a fast release (80% in one hour). The release was studied up to 24h reaching the value of 95%. The Au-3MPS@MTX conjugate was fully characterized by spectroscopic techniques (UV-vis, FTIR) and DLS. Preliminary toxicity tests in the presence of keratinocytes monolayers allowed to assess that the used Au-3MPS are not toxic. The conjugate was then topically used on C57BL/6 mouse normal skin in order to trace the absorption behavior. STEM images clearly revealed the distribution of gold nanoparticles inside the cells. In vitro studies showed that Methotrexate conjugated with Au-3MPS is much more efficient than Methotrexate alone. Moreover, DL50, based on MTT analysis, is 20 folds reduced at 48 h, by the presence of nanoparticles conjugation. UV-vis spectra for in vivo tracing of the conjugate on bare mouse skin after 24h of application, show increased delivery of Methotrexate in the epidermis and dermis using Au-3MPS@MTX conjugate, compared to MTX alone. Moreover we observed absence of the Au-3MPS in the dermis and in the epidermis, suggesting that these layers of the skin do not retain the nanoparticles. Based on our data, we found that the novel Au-3MPS@MTX conjugate is an effective non-toxic carrier for the satisfactory percutaneous absorption of Methotrexate and could help in possible topical treatment of psoriasis.

Candida rugosa lipase immobilization on hydrophilic charged gold nanoparticles as promising biocatalysts: Activity and stability investigations.

In this work, a simple and versatile methodology to obtain two different bioconjugated systems has been developed by the immobilization of Candida rugosa lipase (CRL) on hydrophilic gold nanoparticles functionalized with 2-diethylaminoethanethiol hydrochloride (DEA) or with sodium 3-mercapto-1-propanesulfonate (3MPS), namely Au-DEA@CRL and Au-3MPS@CRL. Both spectroscopic and morphological properties of metal nanoparticles have been deeply investigated. The enzyme loading and lipolytic activity of AuNPs@CRL bioconjugates have been studied with respect to different surface functionalization and compared with the free enzyme. Some physical and chemical parameters had a strong effect on enzyme activity and stability, that were improved in the case of the Au-DEA@CRL bioconjugate, which showed a remarkable biocatalytic performance (95% of residual lipolytic activity compared with free CRL) and stability in experimental conditions concerning pH (range 5-8) and temperature (range 20-60°C), as often required for the industrial scale up of catalytic systems.

Local structure of semicrystalline P3HT films probed by nanofocused coherent X-rays.

The hidden structural properties of semicrystalline polymer films are revealed by nanofocused X-ray scattering studies. X-ray cross-correlation analysis (XCCA) is employed to diffraction patterns from blends of poly(3-hexylthiophene) (P3HT) with gold nanoparticles (AuNPs). Spatially resolved maps of orientational distribution of crystalline domains allow us to distinguish sample regions of predominant face-on morphology, with a continuous transition to edge-on morphology. The average size of crystalline domains was determined to be of the order of 10 nm. As compared to pristine P3HT film, the P3HT/AuNPs blend is characterized by substantial ordering of crystalline domains, which can be induced by Au nanoparticles. The inhomogeneous structure of the polymer film is clearly visualized on the spatially resolved nanoscale 2D maps obtained using XCCA. Our results suggest that the observed changes of the polymer matrix within crystalline regions can be attributed to nanoconfinement in the presence of gold nanoparticles.

Direct interaction of hydrophilic gold nanoparticles with dexamethasone drug: loading and release study.

Water-soluble gold nanoparticles functionalized by sodium 3-mercapto-1-propansulfonate (Au-3MPS) were synthesized with different Au/thiol molar ratios for their ability to interact with biomolecules. In particular, a synthetic glucocorticoid steroid, i.e. dexamethasone (DXM) was selected. Herein, the formation of the Au-3MPS/DXM bioconjugate is reported. Au-3MPS nanoparticles show a plasmon resonance at 520 nm, have a spherical morphology and average size of 7-10 nm. The total number of gold atoms was estimated to be about 10600, with a surface component of 8800 atoms and a number of thiol ligands of about 720, roughly one anchored thiol every 10 surface gold atoms. The drug-nanoparticle interaction occurs through the fluorine atom of DXM and Au(I) atoms on the gold nanoparticle surface. The 3MPS ligands closely pack apart each other to leave room for the DXM, that lies at the gold surface in an unusual, almost parallel feature. The loading efficiency of DXM on Au-3MPS was assessed in the range 70-80%, depending on the thiol content. Moreover, our studies confirmed the drug release of about 70% in 5 days. Thanks to their unique properties, i.e. high water solubility, small size and almost monodispersity, Au-3MPS display high potential in biotechnological and biomedical applications, mainly for the loading and release of water insoluble drugs.

A nanostructured composite based on polyaniline and gold nanoparticles: synthesis and gas sensing properties.

Nanostructured composite materials based on polyaniline (PANI) and gold nanoparticles have been prepared by means of an osmosis based method. Several morphologies have been obtained for the pristine nanoPANI and for nanoPANI-Au composite, ranging from amorphous to sponge-like and spherical shapes. On the basis of this morphological investigation, different materials with high surface area have been selected and tested as chemical interactive materials for room temperature gas and vapor sensing. The resistive sensor devices have been exposed to different vapor organic compounds (VOCs) of interest in the fields of environmental monitoring and biomedical applications, such as toluene, acetic acid, ethanol, methanol, acetonitrile, water, ammonia and nitrogen dioxide. The effect of doping with H2SO4 has been studied for both nanoPANI and nanoPANI-Au samples. In particular, nanoPANI-Au showed sensitivity to ammonia (up to 10 ppm) higher than that to other VOCs or interfering analytes. The facile preparation method and the improved properties achieved for the polyaniline-gold composite materials are significant in the nanomaterials field and have promise for applications in ammonia vapor monitoring.

Structural changes of conjugated Pt-containing polymetallaynes exposed to gamma ray radiation doses.

The effect of (60)Co gamma rays irradiation on the polymetallayne [-Pt(PBu(3))-C≡C-C(6)H(4)-C(6)H(4)-C≡C-](n) (Pt-DEBP) of defined chain length corresponding to 10 repeat units, has been studied in detail. The UV-vis absorption spectra of Pt-DEBP have been recorded in solution upon exposure of the polymetallayne at increasing radiation doses in the range up to 90 Gy, with special care to the features related to low doses. Complex modifications of the chemical structure of Pt-DEBP could be accessed through NMR, FTIR, GPC, and XPS characterizations, which support the attack of Cl and H radicals coming from the radiolysis of the solvent, CHCl(3), to the triple C≡C bonds of the backbone, leading to the formation of chlorinated double and single C-C bonds, with a concomitant increase of the molecular weight due to a recombinant effect of oligomer fragments upon irradiation. The presence of vinyl and single chlorinated moieties has been sustained from the simulation of the UV-vis spectra based on theoretical calculations.

Optical behavior of conjugated Pt-containing polymetallaynes exposed to gamma-ray radiation doses.

The effect of (60)Co γ irradiation on the absorption and emission spectra of the organometallic polymer [-Pt(PBu(3))(2)-C≡C-C(6)H(4)-C(6)H(4)-C≡C-](n) (Pt-DEBP) in chloroform and toluene solutions for dosimetry applications has been studied. The system Pt-DEBP/chloroform can be used for dosimetric applications in two different ways: (i) monitoring of absorption spectra changes for higher doses (higher than 1 Gy), and (ii) monitoring of emission spectra changes for low doses (below 1 Gy). The response of the polymer solution to γ ray doses has been interpreted with the aid of theoretical studies based on time dependent density functional theory (TD-DFT) calculations on the absorption bands of a model complex and of the possible fragments coming from the degradation of the polymer backbone. It has been proposed that the observed changes are promoted by the attack of radicals, from the radiolysis of the solvent, on the polymer triple bonds.

Nanostructured functional co-polymers bioconjugate integrin inhibitors.

Synthesis and properties of bioconjugates based on functionalized polymeric nanoparticles (PNs) and monoclonal anti-Integrin αV CD51 (aI) antibody were investigated. Polymeric and co-polymeric colloidal nanoparticles with different functionalities, i.e., acid, amine, or thiol, namely poly(methylmethacrylate-co-acrylic acid) [P(MMA-co-AA)], poly(methylmethacrylate-co-dimethylpropargylamine) [P(MMA-co-DMPA)], poly(methylmethacrylate-co-allil mercaptane) [P(MMA-co-AM)], were obtained by tailoring emulsion synthesis and fully characterized by means of spectroscopic techniques and scanning electron microscopy (SEM). Bioconjugates (PN/aI) based on P(MMA) or P(MMA-co-AA) were obtained by loading the polymeric nanoparticles with the antibody anti-Integrin with a simple and straightforward immobilization strategy. Bioconjugates qualitative and quantitative loading analyses were carried out by means of polyacrylamide gel electrophoresis 1D-PAGE, MALDI-TOF, and LC/ESI-MS/MS investigations. The biological efficacy of bioconjugates was confirmed by the reduced migration potential of PN/aI-treated human kidney cells (HEK293). The easy immobilization procedure and high immobilization capacity of polymeric nanoparticles together with tuneable chemical functionalities and dimension of the polymeric nanoparticles open applicative perspectives for targeted delivery.

Core shell hybrids based on noble metal nanoparticles and conjugated polymers: synthesis and characterization.

Noble metal nanoparticles of different sizes and shapes combined with conjugated functional polymers give rise to advanced core shell hybrids with interesting physical characteristics and potential applications in sensors or cancer therapy. In this paper, a versatile and facile synthesis of core shell systems based on noble metal nanoparticles (AuNPs, AgNPs, PtNPs), coated by copolymers belonging to the class of substituted polyacetylenes has been developed. The polymeric shells containing functionalities such as phenyl, ammonium, or thiol pending groups have been chosen in order to tune hydrophilic and hydrophobic properties and solubility of the target core shell hybrids. The Au, Ag, or Pt nanoparticles coated by poly(dimethylpropargylamonium chloride), or poly(phenylacetylene-co-allylmercaptan). The chemical structure of polymeric shell, size and size distribution and optical properties of hybrids have been assessed. The mean diameter of the metal core has been measured (about 10-30 nm) with polymeric shell of about 2 nm.

Mono- and bi-functional arenethiols as surfactants for gold nanoparticles: synthesis and characterization.

Stable gold nanoparticles stabilized by different mono and bi-functional arenethiols, namely, benzylthiol and 1,4-benzenedimethanethiol, have been prepared by using a modified Brust's two-phase synthesis. The size, shape, and crystalline structure of the gold nanoparticles have been determined by high-resolution electron microscopy and full-pattern X-ray powder diffraction analyses. Nanocrystals diameters have been tuned in the range 2 ÷ 9 nm by a proper variation of Au/S molar ratio. The chemical composition of gold nanoparticles and their interaction with thiols have been investigated by X-ray photoelectron spectroscopy. In particular, the formation of networks has been observed with interconnected gold nanoparticles containing 1,4-benzenedimethanethiol as ligand.

Self-assembled nanoparticles of functional copolymers for photonic applications.

A modified emulsion copolymerization of phenylacetylene (PA) with hydrophilic monomers having different functions, i.e., acrylic acid (AA) and N,N-dimethylpropargylamine (DMPA) respectively, yields functionalized polymeric P(PA-co-AA) and P(PA-co-DMPA) nanoparticles. The systematic investigation on the experimental parameters affecting size, surface charge and polydispersity of the copolymers (initiator concentration, reaction time, cosolvent and PA/comonomer ratios) allows to modulate the nanoparticle physico-chemical properties. Spherical shaped particles with diameters in the range 80-500 nm, low polydispersity (PI values in the range 1.11-1.30) and different surface charge densities, between 0.44 and 2.87 microC/cm(2), have been consistently obtained and characterized by means of Dynamic Light Scattering (DLS), laser Doppler electrophoretic and Scanning Electron Microscopy (SEM) studies. XPS measurements have provided information on the nanoparticles chemical surface structure and suggest that AA and DMPA units are preferentially distributed on the surface of the spheres. The nanospheres self-assemble giving large domains (9.5 x 14.5 microm). Photonic analysis of the self-assembled copolymeric nanoparticles has been performed by means of Spectroscopic Ellipsometry (SE) and Bragg reflection spectroscopy, both of them demonstrating a three-dimensional photonic crystal property of these systems.

Self-assembled monolayers based on Pd-containing organometallic thiols: preparation and structural characterization.

Multilayers and self-assembled monolayers of on-purpose-prepared organometallic thiolates, trans-[Pd(PBu(3))(2)(SCOCH(3))(2)], trans-[(C(6)H(5)C[triple bond]C)Pd(PBu(3))(2)(SCOCH(3))], and trans,trans-[(CH(3)COS)Pd(PBu(3))(2)(C[triple bond]C-C(6)H(4)-C(6)H(4)-C[triple bond]C)(PBu(3))(2)Pd(SCOCH(3))] were deposited onto gold surfaces. High-resolution X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure measurements allowed us to assess the anchoring of the organometallic thiols onto gold substrates; the interaction occurring at the interface; and their molecular orientation on the surface with tilt angles of about 30 degrees-40 degrees, depending on the investigated molecule. The molecule packing density/coverage was also assessed.

Synthesis and Microstructural Investigations of Organometallic Pd(II) Thiol-Gold Nanoparticles Hybrids.

In this work the synthesis and characterization of gold nanoparticles functionalized by a novel thiol-organometallic complex containing Pd(II) centers is presented. Pd(II) thiol, trans, trans-[dithiolate-dibis(tributylphosphine)dipalladium(II)-4,4'-diethynylbiphenyl] was synthesized and linked to Au nanoparticles by the chemical reduction of a metal salt precursor. The new hybrid made of organometallic Pd(II) thiol-gold nanoparticles, shows through a single S bridge a direct link between Pd(II) and Au nanoparticles. The size-control of the Au nanoparticles (diameter range 2-10 nm) was achieved by choosing the suitable AuCl(4) (-)/thiol molar ratio. The size, strain, shape, and crystalline structure of these functionalized nanoparticles were determined by a full-pattern X-ray powder diffraction analysis, high-resolution TEM, and X-ray photoelectron spectroscopy. Photoluminescence spectroscopy measurements of the hybrid system show emission peaks at 418 and 440 nm. The hybrid was exposed to gaseous NO(x) with the aim to evaluate the suitability for applications in sensor devices; XPS measurements permitted to ascertain and investigate the hybrid -gas interaction.

Lipolytic enzymes with improved activity and selectivity upon adsorption on polymeric nanoparticles.

Nanostructured polystyrene (PS) and polymethylmethacrylate (PMMA) were used as carriers for the preparation of bioconjugates with lipolytic enzymes, such as Candida rugosa lipase (CRL) and Pseudomonas cepacia lipase (PCL). Simple addition of the lipase solution to the polymeric nanoparticles under protein-friendly conditions (pH 7.6) led to the formation of polymer-enzyme bioconjugates. Energy filtered-transmission electron microscopy (EF-TEM) performed on immuno-gold labeled samples revealed that the enzyme preferentially binds to the polymer nanoparticles and that the binding does not affect the nanostructured features of the carriers. The studies performed on the activity of the bioconjugates pointed out that the lipases adsorbed onto polymeric nanoparticles show an improved performance in terms of activity and selectivity with respect to those shown by lipases adsorbed on the same non-nanostructured carriers. The residual activities of CRL and PCL immobilized on nanostructured PMMA and PS reached 60% and 74%, respectively. Moreover, we found that enantioselectivity and pH and thermal stability increase upon immobilization. These results highlight the fact that new protein conformers with improved enantioselectivity stabilized after adsorption on nanoparticles are obtained. On the basis of the chemical structures of the selected polymers and the slopes of the adsorption isotherms, a hydrophobic binding model for lipase/nanostructured polymers is suggested.