Search results for "nanoparticle"
showing 10 items of 2198 documents
Core–Shell Engineering to Enhance the Spectral Stability of Heterogeneous Luminescent Nanofluids
2017
This work was supported by the Spanish Ministerio de Educación y Ciencia (MAT2016-75362-C3-1-R) and by COST Action CM1403. L.L.-P. thanks the Universidad Autónoma de Madrid for the ‘‘Formación de Personal Investigador (FPI-UAM)’’program. P.H.-G. thanks the Spanish Ministerio de Economia y Competitividad for the Juan de la Cierva program (IJCI-2015-24551). M.P. and A.S. thank University of Verona (Italy) for financial support in the framework of the ‘‘Cooperint 2016’’ and “Ricerca di Base 2015” projects. The work of K.S. was supported by Latvian National Research Program IMIS2 (Grant No. 302/2012).
Synthesis of Nanoparticles
2012
In this chapter I describe the synthetic methods for the particles used in this work. Initially bare gold nanorods are synthesized , which are used to investigate continuously the growth of bigger nanoparticles and the protein-membrane interaction on a single particle level . To reduce the single particle linewidth and therefore to increase the sensitivity on changes in the refractive index , these rods are coated with a thin silver shell . Another method to increase the sensitivity of nanoparticles is to produce hollow rod-shaped nanorattles, which were synthesized by Yuriy Khalavka . To investigate the polarization depend scattering spectra of different shapes with the RotPOL setup , diff…
Magnon and Phonon Excitations in Nanosized NiO
2019
Single-crystal, microcrystalline and nanocrystalline nickel oxides (NiO) have been studied by Raman spectroscopy. A new band at ~200 cm-1 and TO-LO splitting of the band at 350–650 cm-1 have been found in the spectra of single-crystals NiO(100), NiO(110) and NiO(111). The Raman spectra of microcrystalline (1500 nm) and nanocrystalline (13–100 nm) NiO resemble those of the single crystals. They all contain the two-magnon band at 1500 cm-1, indicating that the oxides remain at room temperature in the antiferromagnetic phase. Besides, a new sharp Raman band has been observed at 500 cm-1 in nanocrystalline NiO. Its temperature dependence suggests the magnetic origin of the band, possibly associ…
Spectroscopic Signature of the Superparamagnetic Transition and Surface Spin Disorder in CoFe2O4 Nanoparticles
2012
Phonons are exquisitely sensitive to finite length scale effects in a wide variety of materials. To investigate confinement in combination with strong magnetoelastic interactions, we measured the infrared vibrational properties of CoFe(2)O(4) nanoparticles and compared our results to trends in the coercivity over the same size range and to the response of the bulk material. Remarkably, the spectroscopic response is sensitive to the size-induced crossover to the superparamagnetic state, which occurs between 7 and 10 nm. A spin-phonon coupling analysis supports the core-shell model. Moreover, it provides an estimate of the magnetically disordered shell thickness, which increases from 0.4 nm i…
Guided hierarchical co-assembly of soft patchy nanoparticles.
2013
Different polymers can be used in combination to produce coexisting nanoparticles of different symmetry and tailored to co-assemble into well-ordered binary and ternary hierarchical structures. There is considerable practical interest in developing the tools to fabricate multicomponent artificial systems that mimic the hierarchical ordering seen in the natural world — complex biomaterials can be assembled from the simple but precisely defined molecular building blocks. Andre Groschel and colleagues have developed a bottom-up approach that's a step in that direction. Previously they designed simple linear polymers that self-assemble in solution to produce monodisperse nanoparticles with well…
Brush Conformation of Polyethylene Glycol Determines the Stealth Effect of Nanocarriers in the Low Protein Adsorption Regime
2021
For nanocarriers with low protein affinity, we show that the interaction of nanocarriers with cells is mainly affected by the density, the molecular weight, and the conformation of polyethylene glycol (PEG) chains bound to the nanocarrier surface. We achieve a reduction of nonspecific uptake of ovalbumin nanocarriers by dendritic cells using densely packed PEG chains with a "brush" conformation instead of the collapsed "mushroom" conformation. We also control to a minor extent the dysopsonin adsorption by tailoring the conformation of attached PEG on the nanocarriers. The brush conformation of PEG leads to a stealth behavior of the nanocarriers with inhibited uptake by phagocytic cells, whi…
Impact of nanoparticles on the environmental sustainability of polymer nanocomposites based on bioplastics or recycled plastics – A review of life-cy…
2022
Adding nanoparticles to a host polymer can lead to performance improvements that can be twice as beneficial to the environment: first, sustainable nanocomposites based on bioplastics or recycled plastics could replace ubiquitous petroleum-based polymers; second, substantial plastic saving could be achieved by profiting from the superior specific properties of the nanocomposites. Nevertheless, the inherent environmental burden of nanoparticles can compromise the expected benefits. Here we address the controversial issue of the environmental sustainability of “green” polymer nanocomposites based on bioplastics and recycled plastics. A critical review of life-cycle assessment studies regarding…
Monitoring Thiol–Ligand Exchange on Au Nanoparticle Surfaces
2018
Surface functionalization of nanoparticles (NPs) plays a crucial role in particle solubility and reactivity. It is vital for particle nucleation and growth as well as for catalysis. This raises the quest for functionalization efficiency and new approaches to probe the degree of surface coverage. We present an (in situ) proton nuclear magnetic resonance (1H NMR) study on the ligand exchange of oleylamine by 1-octadecanethiol as a function of the particle size and repeated functionalization on Au NPs. Ligand exchange is an equilibrium reaction associated with Nernst distribution, which often leads to incomplete surface functionalization following “standard” literature protocols. Here, we show…
Colloidal Self-assembled Nanosphere Arrays for Plasmon-enhanced Light Trapping in Thin Film Silicon Solar Cells
2014
To realize high-efficiency thin-film silicon solar cells it is crucial to develop light-trapping methods that can increase absorption of the near- bandgap light in the silicon material. That can be achieved using the far-field scattering properties of metal nanoparticles (MNP) sustaining surface plasmons. The MNPs should be inserted in the back of the cell, embedded in the transparent conductive oxide (TCO) layer which separates the rear mirror from the silicon layers. In this way, a plasmonic back reflector (PBR) is constructed that can redirect light at angles away from the incidence direction and thereby increase its path length in the cell material. In this work, a novel technique is pr…
Molybdenum Trioxide Nanoparticles with Intrinsic Sulfite Oxidase Activity
2014
Sulfite oxidase is a mitochondria-located molybdenum-containing enzyme catalyzing the oxidation of sulfite to sulfate in the amino acid and lipid metabolism. Therefore, it plays a major role in detoxification processes, where defects in the enzyme cause a severe infant disease leading to early death with no efficient or cost-effective therapy in sight. Here we report that molybdenum trioxide (MoO3) nanoparticles display an intrinsic biomimetic sulfite oxidase activity under physiological conditions, and, functionalized with a customized bifunctional ligand containing dopamine as anchor group and triphenylphosphonium ion as targeting agent, they selectively target the mitochondria while bein…