Photothermally controlled methotrexate release system using β-cyclodextrin and gold nanoparticles

The inclusion compound (IC) of cyclodextrin (CD) containing the antitumor drug Methotrexate (MTX) as a guest molecule was obtained to increase the solubility of MTX and decrease its inherent toxic effects in nonspecific cells. The IC was conjugated with gold nanoparticles (AuNPs), obtained by a chemical method, creating a ternary intelligent delivery system for MTX molecules, based on the plasmonic properties of the AuNPs. Irradiation of the ternary system, with a laser wavelength tunable with the corresponding surface plasmon of AuNPs, causes local energy dissipation, producing the controlled release of the guest from CD cavities. Finally, cell viability was evaluated using MTS assays for β-CD/MTX and AuNPs + β-CD/MTX samples, with and without irradiation, against HeLa tumor cells. The irradiated sample of the ternary system AuNPs + β-CD/MTX produced a diminution in cell viability attributed to the photothermal release of MTX

Modification of silicon surface with redox molecules derived from ferrocene

This study presents a new method to bind active redox molecules derived of ferrocene to the surface of single crystal silicon. The procedure consists in the reaction of hydrogenated silicon with allyl bromide activated with white light and its subsequent reaction with monolithio ferrocene in order to create a covalent union between the redox molecule and the semiconductor surface. The layers formed are electrochemically active and present a quasireversible electrochemical process which is attributed to the ferrocene molecules which are bound to the silicon surface. X-ray photoelectron spectroscopy (XPS) analysis confirms the presence of ferrocene molecules on the silicon surface

γ-Cyclodextrin/alkylthiol inclusion compounds crystals as substrates for the formation and immobilization of gold nanoparticles produced by magnetron sputtering

© Springer Science+Business Media Dordrecht 2014. In this work, we report the nanodecoration of microcrystals of inclusion compound (IC) of γ-cyclodextrin (γ-CD) that contain octanethiol, decanethiol and dodecanethiol. Crystals of these ICs provide a suitable environment for nucleation, growth and immobilization of gold nanoparticles that were obtained by the magnetron sputtering technique. The use of γ-CD IC substrates with a specific surface morphology (i.e., the functional group of the guest molecule faces outward preferentially from a crystal plane) is an efficient method for the preparation of AuNPs with low size dispersion, which is due to the high affinity between the functional group of the surfactant alkylthiol guest with the metal nanoparticles

Application of photochemical method in the synthesis of Ga2O3 X thin films co-doped with terbium and europium

Artículo de publicación ISIGa2O3 X thin films co-doped with terbium and europium have been prepared by photochemical metalorganic deposition. In this process, solutions containing Ga(III), Tb(III) and Eu(III) 2,2,6,6-tetramethyl-3,5- heptanedionate complexes were spin coated on silicon and quartz substrates. Upon irradiation, the photosensitive of the complexes precursors undergoes decomposition, leaving a gallium oxide amorphous thin film containing terbium and europium. The photo-reactivity of these films was monitored by UV vis and FT-IR spectroscopy. The obtained films were characterized by X-ray photoelectron spectroscopy and X-ray diffraction. Under UV light excitation (254 nm) the doped films (Ga2O3 XeTb) show the characteristic emissions associated to 5D4 /7FJ (J ¼ 6, 5, 4, 3) transitions of terbium ion. However, these emissions decrease with the co-doped films (Ga2O3 XeTbeEu). Analysis suggests an energy transfer process among terbium and europium ions.The authors are grateful to the financial support of National Fund for Scientific and Technological Development, Chile. (FONDECYT N 1100045)

Photothermally Controlled Methotrexate Release System Using β-Cyclodextrin and Gold Nanoparticles

The inclusion compound (IC) of cyclodextrin (CD) containing the antitumor drug Methotrexate (MTX) as a guest molecule was obtained to increase the solubility of MTX and decrease its inherent toxic effects in nonspecific cells. The IC was conjugated with gold nanoparticles (AuNPs), obtained by a chemical method, creating a ternary intelligent delivery system for MTX molecules, based on the plasmonic properties of the AuNPs. Irradiation of the ternary system, with a laser wavelength tunable with the corresponding surface plasmon of AuNPs, causes local energy dissipation, producing the controlled release of the guest from CD cavities. Finally, cell viability was evaluated using MTS assays for β-CD/MTX and AuNPs + β-CD/MTX samples, with and without irradiation, against HeLa tumor cells. The irradiated sample of the ternary system AuNPs + β-CD/MTX produced a diminution in cell viability attributed to the photothermal release of MTX

Evidence of the Disassembly of alpha-Cyclodextrin-octylamine Inclusion Compounds Conjugated to Gold Nanoparticles via Thermal and Photothermal Effects

Cyclodextrin (CD) molecules form inclusion compounds (ICs), generating dimers that are capable of encapsulating molecules derived from long-chain hydrocarbons. The aim of this study is to evaluate the structural changes experienced by ICs in solution with increasing temperatures. For this, a nuclear magnetic resonance (H-1-NMR) titration was performed to determinate the stoichiometric alpha-cyclodextrin (alpha-CD):octylamine (OA) 2:1 and binding constant (k = 2.16 M-2) of ICs. Solution samples of alpha-CD-OA ICs conjugated with gold nanoparticles (AuNPs) were prepared, and H-1-NMR spectra at different temperatures were recorded. Comparatively, H-1-NMR spectra of the sample irradiated with a laser with tunable wavelengths, with plasmons of conjugated AuNPs, were recorded. In this work, we present evidence of the disassembly of ICs conjugated with AuNPs. Thermal studies demonstrated that, at 114 degrees C, there are reversible rearrangements of the host and guests in the ICs in a solid state. Migration movements of the guest molecules from the CD cavity were monitored via temperature-dependent H-1-NMR, and were verified comparing the chemical shifts of octylamine dissolved in deuterated dimethylsulfoxide (DMSO-d(6)) with the OA molecule included in alpha-CD dissolved in the same solvent. It was observed that, at 117 degrees C, OA exited the alpha-CD cavity. CD IC dimer disassembly was also observed when the sample was irradiated with green laser light.Laboratory NMR USACH, Fondecyt, Conicy

Synthesis and evaluation of bis-b-diketonate dioxotungsten(VI) complexes as precursors for the photodeposition of WO3 films

In this paper non-stoichiometric tungsten oxide thin films have been successfully prepared by direct UV irradiation of bis-b-diketonate dioxotungsten(VI) precursor complexes spin-coated Si(1 0 0) substrates. Photodeposited films were characterized by Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) and the surface morphology examined by Atomic Force Microscopy (AFM). The results of XRD analysis showed that the as-photodeposited WO3 x films are amorphous and have a rougher surface than thermally treated films. Post-annealing of the films in air at 500 C transforms the sub-oxides to a monoclinic WO3 phase.This research was supported by FONDECYT, Chile (Project No. 1080225) and Pontificia Universidad Católica de Valparaíso (Project D.I. No. 125.727/08)

Molybdenum trioxide thin films doped with gold nanoparticles grown by a sequential methodology: photochemical metal-organic deposition (PMOD) and DC-magnetron sputtering

Gold nanoparticles (AuNPs) were deposited by DC-magnetron sputtering onto molybdenum trioxide (MoO3) thin films grown by Photochemical Metal-Organic Deposition (PMOD) on Si(100) and borosilicate glass substrates. The chemical, optical and morphology properties of the films were studied by UV/Vis Spectroscopy, Scanning Electron Microscopy (SEM), X-Ray Photoelectron Spectroscopy (XPS), and X-Ray Diffraction (XRD). SEM revealed that AuNPs formed after 5 s of sputtering. AuNPs are spherical and have both an average diameter of 18 nm and a relatively narrow size distribution. As the deposition time increases, larger structures are formed by an aggregation of AuNPs. XPS studies of the AuNP/MoO3 films on Si(100) showed the presence of Mo(VI) and Mo(V), which indicated that the films were primarily non-stoichiometric molybdenum oxides. The occurrence of oxygen vacancies in the substrate play an important role to stabilize the AuNP