PubMed Health⌕ Search

Biomedical subjects

Jorge Pérez-Juste

Publications and source records attributed to Jorge Pérez-Juste.

5 recordsLinked to original sources
PubMed2006

Seeded growth of submicron Au colloids with quadrupole plasmon resonance modes.

A modified seeded growth process has been used for the controlled synthesis of quasispherical, CTAB-stabilized gold nanoparticles from 12 up to 180 nm with narrow size distributions. The UV-visible spectra of the aqueous colloids show distinct bands corresponding to dipole and quadrupole plasmon modes, for diameters above 100 nm, in close agreement with predictions based on Mie theory. The assignment of the modes is demonstrated by calculation of near field enhancement maps based on the boundary element method. Apart from other applications, since absorption is drastically reduced above 600 nm, while scattering is largely increased, these particles open new possibilities for construction of highly efficient photonic structures.

Journal Article↗
PubMed2006

Optically active poly(dimethylsiloxane) elastomer films through doping with gold nanoparticles.

Poly(dimethylsiloxane) (PDMS) elastomer films synthesized through a cross-linking reaction between hydroxyl-terminated or vinyl-terminated PDMS have been homogeneously doped with silica-coated Au nanoparticles. The nanocomposite synthesis involves mixing a preformed colloid of surface-modified metal nanoparticles with the elastomer film precursors. The homogeneous distribution of nanoparticles is demonstrated through the presence of well defined plasmon absorbance bands in the visible, which clearly show that the composites retain the characteristic optical properties of single Au nanoparticles. The metal particle concentration could be easily tailored either through the amount or the concentration of the nanoparticle colloid added. Since the Au nanoparticles are not cross-linked to the polymer and the concentration of particles is relatively low, we postulate that the presence of the nanoparticles does not affect the mechanical properties of the films, though this remains to be confirmed.

Dimethylpolysiloxanes↗
PubMed2005

Spatially-directed oxidation of gold nanoparticles by Au(III)-CTAB complexes.

Gold nanoparticles are readily oxidized by Au(III) in the presence of cetyl-trimethylammonium bromide (CTAB). Oxidation occurs preferentially at surface sites with higher curvature. Conversely, oxidation with cyanide ions in the absence of CTAB leads to uniform oxidation over the whole surface. Examples of the spatially directed oxidation are provided using large, irregular spheres, nanocubes, and nanorods. We conclude that the mechanism of oxidation depends on whether the oxidant is attached to CTAB micelles. It is postulated that the CTAB micelles approach the nanoparticles preferentially at the tips, leading to spatially directed oxidation.

Letter↗
PubMed2004

Flexible ureasil hybrids with tailored optical properties through doping with metal nanoparticles.

Hybrid organic-inorganic nanocomposites containing uniform distributions of metal nanoparticles have been prepared by mixing a preformed nanoparticle colloid with the precursors of a ureasil, prior to the sol-gel transition. These nanocomposites possess not only high optical quality and optical features dictated by the size and shape of the nanoparticle dopants but also a high degree of flexibility, which can largely enhance the range of applications in practical devices. The deposition of a uniform silica shell on the nanoparticle surface prior to the sol-gel transition was found to be required to maintain the colloidal stability during the process and, thus, to retain the optical properties in the final nanocomposite material. This method can be readily extended to other materials, such as semiconductor and magnetic nanoparticles.

Journal Article↗