			Home About us Contact

Nanoparticle Systems (nanoparticle + system)

Distribution by Scientific Domains

Polymers and Materials Science	46%
Physics and Astronomy	26%

Distribution within Polymers and Materials Science

General & Introductory Materials Science	71%
Polymer Science & Technology General	28%

Selected Abstracts

Enzyme-Responsive Nanoparticle Systems,

ADVANCED MATERIALS, Issue 22 2008
James E. Ghadiali
Abstract Inorganic nanoparticles and their accompanying diverse physical properties are now virtually in routine use as imaging tools in cell-biology. In addition to serving as excellent contrast agents, their size- and environment-dependent optical and magnetic properties can be harnessed to create enzyme biosensor devices of extremely high sensitivity, whilst circumventing the numerous technical limitations associated with traditional enzyme assays. In this Research News article we discuss recent advances in field of enzyme-responsive nanoparticle systems, where the activity of an enzyme elicits a specific response in the nanoparticle assembly to produce a signal relating to enzyme activity, focusing on three important systems: DNA-structured nanoparticles, protein kinases and proteases. [source]

PEI,PEG,Chitosan-Copolymer-Coated Iron Oxide Nanoparticles for Safe Gene Delivery: Synthesis, Complexation, and Transfection

ADVANCED FUNCTIONAL MATERIALS, Issue 14 2009
Forrest M. Kievit
Abstract Gene therapy offers the potential of mediating disease through modification of specific cellular functions of target cells. However, effective transport of nucleic acids to target cells with minimal side effects remains a challenge despite the use of unique viral and non-viral delivery approaches. Here, a non-viral nanoparticle gene carrier that demonstrates effective gene delivery and transfection both in vitro and in vivo is presented. The nanoparticle system (NP,CP,PEI) is made of a superparamagnetic iron oxide nanoparticle (NP), which enables magnetic resonance imaging, coated with a novel copolymer (CP,PEI) comprised of short chain polyethylenimine (PEI) and poly(ethylene glycol) (PEG) grafted to the natural polysaccharide, chitosan (CP), which allows efficient loading and protection of the nucleic acids. The function of each component material in this nanoparticle system is illustrated by comparative studies of three nanoparticle systems of different surface chemistries, through material property characterization, DNA loading and transfection analyses, and toxicity assessment. Significantly, NP,CP,PEI demonstrates an innocuous toxic profile and a high level of expression of the delivered plasmid DNA in a C6 xenograft mouse model, making it a potential candidate for safe in vivo delivery of DNA for gene therapy. [source]

Eudragit RL100 nanoparticle system for the ophthalmic delivery of cloricromene

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2004
Claudio Bucolo
A Eudragit RL100 polymer nanoparticle system loaded with cloricromene was prepared and characterized on the basis of physicochemical properties, stability and drug release features. To investigate the ocular bioavailability of cloricromene after inclusion in the polymer matrix, the new nanoparticle system was topically administered in the rabbit eye and compared with an aqueous solution of the same drug. The nanoparticle system showed interesting size distribution and surface charge values, suitable for ophthalmic application. The results indicated that the dispersion of cloricromene within Eudragit RL100 polymer nanoparticles increased its ocular bioavailability and enhanced the biopharmaceutical profile. The new cloricromene-loaded nanoparticle system described here may be useful in clinical practice. [source]

Magnetic field-dependence study of the magnetocaloric properties of a superparamagnetic nanoparticle system: a Monte Carlo simulation

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2008
D. Serantes
Abstract The influence of the applied magnetic field on the magnetocaloric properties of a fine magnetic particle system has been studied using a Monte Carlo technique. By simulating zero field cooling (ZFC) curves under different strengths of the applied magnetic field, we have analyzed the variation of the entropy for temperatures above the maximum of the ZFC curves, where the process is reversible. The entropy curves have been observed to behave in a different fashion at low values of the magnetic field, where the peak only slightly shifts to higher temperatures with increasing fields. For larger fields, the peak rapidly shifts to higher temperatures, while the overall shape of the curve broadens over a wide temperature range. It is also observed that the blocking temperature as a function of the magnetic field shows the feature of a change from a bell-like shape to a monotonically decreasing function, resembling what is found experimentally for intermediate values of the sample concentration. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Identification of a Highly Efficient Alkylated Pincer Thioimido,Palladium(II) Complex as the Active Catalyst in Negishi Coupling

CHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2009
Jing Liu Dr.
Abstract PdIIate complex: A novel alkylated pincer thioimido,Pd complex generated from a catalyst precursor and basic organometallic reagents (RM) was observed by in situ IR, 1H,NMR, and 13C,NMR spectroscopies for the first time and proved to be the active catalyst in stoichiometric and catalytic reactions of aryl iodides with RM (see scheme). The catalyst, as an electron-rich PdII species, promoted the Negishi coupling of aryl iodides and alkylzinc reagents with high efficiency, even at low temperatures (0 or ,20,°C). The induction period of Negishi coupling catalyzed by pincer thioamide,palladium complex 1 was investigated. A heterogeneous mechanism was excluded by kinetic studies and comparison with Negishi coupling reactions promoted by Pd(OAc)2/Bu4NBr (a palladium,nanoparticle system). Tetramer 2 was isolated from the reaction of 1 and organozinc reagents. Dissociation of complex 2 by PPh3 was achieved, and the structure of resultant complex 8 was confirmed by X-ray diffraction analysis. A novel alkylated pincer thioimido,PdII complex, 7, generated from catalyst precursor 1 and basic organometallic reagents (RM), was observed by in situ IR, 1H,NMR, and 13C,NMR spectroscopy for the first time. The reaction of 7 with methyl 2-iodobenzoate afforded 74,% of the cross-coupled product, methyl 2-methylbenzoate, together with 60,% of PdII complex 2. Furthermore, the catalyst, as an electron-rich PdII species, efficiently promoted the Negishi coupling of aryl iodides and alkylzinc reagents without an induction period, even at low temperatures (0,°C or ,20,°C). To evaluate the influence of the catalyst structure upon the induction period, complex 9 was prepared, in which the nBu groups of 1 were displaced by more bulky 1,3,5-trimethylphenyl groups. Trimer 10 was isolated from the reaction of complex 9 and basic organometallic reagents such as CyZnCl or CyMgCl (Cy: cyclohexyl); this is consistent with the result obtained with complex 1. The rate in the induction period of the model reaction catalyzed by 9 was faster than that with 1. Plausible catalytic cycles for the reaction, based upon the experimental results, are discussed. [source]

PEI,PEG,Chitosan-Copolymer-Coated Iron Oxide Nanoparticles for Safe Gene Delivery: Synthesis, Complexation, and Transfection

Designed Fabrication of Silica-Based Nanostructured Particle Systems for Nanomedicine Applications,

ADVANCED FUNCTIONAL MATERIALS, Issue 23 2008
Yuanzhe Piao
Abstract Suitably integrating multiple nanomaterials into nanostructured particle systems with specific combinations of properties has recently attracted significant attention in the research community. In particular, numerous particle systems have been designed and fabricated by integrating diverse materials with monodispersed silica nanoparticles. One or more distinct nanomaterials can be assembled on, encapsulated within, or integrated both inside and on the surface of silica nanoparticles using different chemistries and techniques to create multifunctional nanosystems. Research on these particle systems for biomedical applications has progressed rapidly during recent years due to the synergistic advantages of these complexes compared to the use of single components. This feature article surveys recent research progress on the fabrication strategies of these nanoparticle systems and their applications to medical diagnostics and therapy, thereby paving the way for the emerging field of nanomedicine. [source]

Enzyme-Responsive Nanoparticle Systems,

Singularity-Free Brownian Dynamics Analyses of Rotational Dynamics: Non-Spherical Nanoparticles in Solution

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 5 2005
Stine Nalum Naess
Abstract Summary: From kinetic theory we have rigorously derived singularity-free Brownian dynamics analyses of nanoparticle rotational dynamics. The rigid non-spherical nanoparticles incorporate all three rotational degrees of freedom. This was achieved by using the components of Cartesian rotation vectors as the generalized coordinates describing angular orientation. The new results constitute an important advance compared to the situation when Eulerian angles specify angular orientation. Our finding eliminates one of the main longstanding obstacles to detailed studies of nanoparticle rotational dynamics in the diffusion time domain. The described formalism is applicable to a wide range of nanoparticle systems including liquid crystals, biopolymers, and colloids. [source]

Thermal stability of Fe, Co, Ni metal nanoparticles

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2006
L. F. Cao
Abstract The thermal stability of metal nanoparticles is discussed in both melting thermodynamics and interface thermodynamics. Emphases are put on the size and shape dependence of melting temperature, critical size and vacancy-formation energy of both freestanding and embedded metal nanoparticles. The melting temperature depression and superheating phenomena for reported nanoparticle systems are explained. Critical sizes of Fe, Co, Ni metal nanocrystals that the crystals keep their crystallinity are calculated and the corresponding minimum melting temperatures predicted. The vacancy-formation energies of Fe, Co, Ni small particles are also calculated as a reference. Theoretical predictions are consistent with experimental results. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Monodisperse magnetic nanoparticles for biomedical applications

POLYMER INTERNATIONAL, Issue 7 2007
Chenjie Xu
Abstract Magnetic nanoparticles that are superparamagnetic with high saturation moment have great potential for biomedical applications. Solution-phase syntheses have recently been applied to make various kinds of monodisperse magnetic nanoparticles with standard deviation in diameter of less than 10%. However, the surface of these nanoparticles is coated with a layer of hydrocarbon molecules due to the use of lipid-like carboxylic acid and amine in the syntheses. Surface functionalization leads to the formation of water-soluble nanoparticles that can be further modified with various biomolecules. Such functionalization has brought about several series of monodisperse magnetic nanoparticle systems that have shown promising applications in protein or DNA separation, detection and magnetic resonance imaging contrast enhancement. The goal of this mini review is to summarize the recent progress in the synthesis and surface modification of monodisperse magnetic nanoparticles and their applications in biomedicine. Copyright © 2007 Society of Chemical Industry [source]

A model predicting delivery of saquinavir in nanoparticles to human monocyte/macrophage (Mo/Mac) cells

BIOTECHNOLOGY & BIOENGINEERING, Issue 5 2008
D. Ece Gamsiz
Abstract Modeling the influence of a technology such as nanoparticle systems on drug delivery is beneficial in rational formulation design. While there are many studies showing drug delivery enhancement by nanoparticles, the literature provides little guidance regarding when nanoparticles are useful for delivery of a given drug. A model was developed predicting intracellular drug concentration in cultured cells dosed with nanoparticles. The model considered drug release from nanoparticles as well as drug and nanoparticle uptake by the cells as the key system processes. Mathematical expressions for these key processes were determined using experiments in which each process occurred in isolation. In these experiments, intracellular delivery of saquinavir, a low solubility drug dosed as a formulation of poly(ethylene oxide)-modified poly(epsilon- caprolactone) (PEO,PCL) nanoparticles, was studied in THP-1 human monocyte/macrophage (Mo/Mac) cells. The model accurately predicted the enhancement in intracellular concentration when drug was administered in nanoparticles compared to aqueous solution. This simple model highlights the importance of relative kinetics of nanoparticle uptake and drug release in determining overall enhancement of intracellular drug concentration when dosing with nanoparticles. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc. [source]

HRTEM, Raman and optical study of CdS1,xSex nanocrystals embedded in silicate glass

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 13 2004
V. Bellani
Abstract We studied CdS1,xSex nanocrystals embedded in a silicate glass by means of complementary techniques like high resolution transmission electron microscopy (HRTEM), micro-Raman spectroscopy and optical transmission and reflectivity. Transmission Electron Microscopy gives complete information on crystallization and size distribution of the nanocrystals wile Raman scattering is particularly useful in the determination of the composition of the nanocrystals for low-concentration or small-crystallite size composite. Having the size distribution and composition of the nanocrystals we have explained the transmission spectra of the studied samples. Optical transmission spectra evidence the quantization of the electronic states of the nanoparticles system with a size distribution described by a Gaussian function. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Cooling-field dependence of exchange bias and asymmetric reversal modes in a nanoparticles system with ferromagnetic core and antiferromagnetic matrix morphology

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2009
Yong Hu
Abstract Interest in exchange bias (EB) in magnetic nanoparticles has increased in the past few years by virtue of its potential for application in fields such as ultrahigh-density magnetic recording. A modified Monte Carlo Metropolis method is performed to simulate the effect of cooling field on EB and asymmetric reversal modes of a granular system of ferromagnetic (FM) nanoparticles embedded in an antiferromagnetic (AFM) matrix, based on three-dimensional classical Heisenberg model. The results show that the EB first decreases slightly due to the energy barriers in the antiferromagnet, while the coercivity and vertical magnetization shift increase with the increase of cooling field, finally, they all level off as the cooling field is strong enough. Whereas the cooling- and measuring-field angular dependence of asymmetric reversal modes reveal asymmetric reversal mechanism and interesting rotation process of FM spins, confirming the existence of the net magnetization on the surface of AFM matrix. The reason may be due to the energy competition and geometric frustration of system. However, the strong interfacial coupling may change the intrinsic atomic configuration of antiferromagnet to influence the EB and reversal modes. [source]