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Nanoparticles Based (nanoparticle + base)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Chemistry	50%

Selected Abstracts

Blue Luminescence of ZnO Nanoparticles Based on Non-Equilibrium Processes: Defect Origins and Emission Controls

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2010
Haibo Zeng
Abstract High concentrations of defects are introduced into nanoscale ZnO through non-equilibrium processes and resultant blue emissions are comprehensively analyzed, focusing on defect origins and broad controls. Some ZnO nanoparticles exhibit very strong blue emissions, the intensity of which first increase and then decrease with annealing. These visible emissions exhibit strong and interesting excitation dependences: 1) the optimal excitation energy for blue emissions is near the bandgap energy, but the effective excitation can obviously be lower, even 420,nm (2.95,eV,<,Eg,=,3.26,eV); in contrast, green emissions can be excited only by energies larger than the bandgap energy; and, 2) there are several fixed emitting wavelengths at 415, 440, 455 and 488,nm in the blue wave band, which exhibit considerable stability in different excitation and annealing conditions. Mechanisms for blue emissions from ZnO are proposed with interstitial-zinc-related defect levels as initial states. EPR spectra reveal the predominance of interstitial zinc in as-prepared samples, and the evolutions of coexisting interstitial zinc and oxygen vacancies with annealing. Furthermore, good controllability of visible emissions is achieved, including the co-emission of blue and green emissions and peak adjustment from blue to yellow. [source]

pH-Dependent Assembly of DNA,Gold Nanoparticles Based on the i-Motif: A Switchable Device with the Potential of a Nanomachine

HELVETICA CHIMICA ACTA, Issue 9 2006
Frank Seela
Abstract The pH-dependent self-assembling of gold nanoparticles is described. Oligonucleotides containing four or six consecutive dC residues are immobilized on 15-nm gold nanoparticles. Their assembly is based on the formation of a DNA i-motif as determined by the color change from red to blue between pH,5.5 and 6.5. The process occurs within a narrow pH range and is reversible. The i-motif is formed by the antiparallel intercalation of two parallel duplexes provided by two different gold nanoparticles. This assembly process can be utilized to generate novel systems for colorimetric sensing, applications in medical imaging and therapy, and for the construction of a proton-driven nanomachine. [source]

Asymmetric Functionalization of Nanoparticles Based on Thermally Addressable DNA Interconnects,

ADVANCED MATERIALS, Issue 17 2006
F. Huo
The synthesis of nanoparticles asymmetrically functionalized with oligonucleotides is reported. The method provides excellent control over the placement of oligonucleotides on the surface of only one hemisphere of each particle (see figure). This new synthetic capability allows one to introduce valency into such structures and then use that valency to direct particle-assembly events. [source]

A Generic Approach to Monofunctionalized Protein-Like Gold Nanoparticles Based on Immobilized Metal Ion Affinity Chromatography

CHEMBIOCHEM, Issue 4 2006
Raphaël Lévy Dr.
Control of a peptide-capped gold-nanoparticle (NP) surface with single-molecule accuracy is demonstrated. Immobilized metal ion affinity chromatography (IMAC) has been used to separate peptide-capped NPs as a function of the number of molecular labels (see scheme). The method described in this paper is simple, quantitative and directly applicable to the preparation of monofunctionalized nanoparticles with any water-soluble chemical moieties. [source]