Endocytosis of dextran and silan-coated magnetite nanoparticles and the effect of intracellular hyperthermia on human mammary carcinoma cells in vitro

To obtain more evidence for intracellular magnetic fluid hyperthermia (MFH), endocytosis and hyperthermia efficacy of silan and dextran magnetite was investigated. Differential endocytosis was observed in dependence of nanoparticle and cell type. Clonogenic survival was 3-fold lower after MFH versus waterbath hyperthermia. The selective \u27remote inactivation\u27 of cancer cells by an AC magnetic field has been demonstrated in vitro

Presentation of a new magnetic field therapy system for the treatment of human solid tumors with magnetic fluid hyperthermia

Magnetic fluid hyperthermia (MFH) selectively heats up tissue by coupling alternating current (AC) magnetic fields to targeted magnetic fluids, so that boundaries of different conductive tissues do not interfere with power absorption. In this paper, a new AC magnetic field therapy system for clinical application of MFH is described. With optimized magnetic nanoparticle preparations it will be used for target-specific glioblastoma and prostate carcinoma therapy

Endocytosis of dextran and silan-coated magnetite nanoparticles and the effect of intracellular hyperthermia on human mammary carcinoma cells in vitro

To obtain more evidence for intracellular magnetic fluid hyperthermia (MFH), endocytosis and hyperthermia efficacy of silan and dextran magnetite was investigated. Differential endocytosis was observed in dependence of nanoparticle and cell type. Clonogenic survival was 3-fold lower after MFH versus waterbath hyperthermia. The selective 'remote inactivation' of cancer cells by an AC magnetic field has been demonstrated in vitro

A nonviral DNA delivery system based on surface modified silica-nanoparticles can efficiently transfect cells in vitro

Diverse polycationic polymers have been used as nonviral transfection agents. Here we report the ability of colloidal silica particles with covalently attached cationic surface modifications to transfect plasmid DNA in vitro and make an attempt to describe the structure of the resulting transfection complexes. In analogy to the terms lipoplex and polyplex, we propose to describe the nanoparticle-DNA complexes by the term 'nanoplex'. Three batches, Si10E, Si100E, and Si26H, sized between 10 and 100 nm and with ζ potentials ranging from +7 to +31 mV at pH 7.4 were evaluated. The galactosidase expression plasmid DNA pCMVβ was immobilized on the particle surface and efficiently transfected Cos-1 cells. The transfection activity was accompanied by very low cytotoxicity, with LD50 values in the milligrams per milliliter range. The most active batch, Si26H, was produced by modification of commercially available silica particles with N-(6-aminohexyl)-3-aminopropyltrimethoxysilane, yielding spherical nanoparticles with a mean diameter of 26 nm and a ζ potential of +31 mV at pH 7.4. Complexes of Si26H and pCMVβ plasmid DNA formed at w/w ratios of 10 were most effective in promoting transfection of Cos-1 cells in the absence of serum. At this ratio, >90% of the DNA was associated with the particles, yielding nanoplexes with a net negative surface charge. When the transfection medium was supplemented with 10% serum, maximum gene expression was observed at a w/w ratio of 30, at which the resulting particle-DNA complexes possessed a positive surface charge. Transfection was strongly increased in the presence of 100 µM chloroquine in the incubation medium and reached approximately 30% of the efficiency of a 60 kDa polyethylenimine. In contrast to polyethylenimine, no toxicity was observed at the concentrations required. Atomic force microscopy of Si26H-DNA complexes revealed a spaghetti-meatball-like structure. The surface of complexes prepared at a w/w ratio of 30 was dominated by particles half-spheres. Complex sizes correlated well with those determined previously by dynamic light scattering

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Aqueous sol-gel derived nanocomposite coating materials

Sol-gel reactions, in general, have to take place in organic solvents in order to control the hydrolysis and condensation reaction. This leads to drawbacks in applications, since the organic solvent vapor concnetration has to be controlled for example in ocoating applications for environmental, health or security reasons. For this reason, a reaction route has been developed to produce coating precursors stable against water as solvent. To achieve this, conventional electrostatically stabilized sols obtained either by hydrolysis and condensation or commercially availabe sols (e.g. SiO2 sols) have been surface modified to reduce the particle-to-particle interaction and electrosterically stabilized precursors compatible to water have been obtained. By use of alkoxy silanes as surface modifiers, water-dispersable nanoparticulate liquid coating systems have been prepared, for example, with boehmite, SiO2 or TiO2 as nanoparticles to be crosslinked after coating thermally by inorganic condensation and organic condensation or polymerization reactions. Thus, aqueous sol-gel coating systems have been prepared with EtOH contents below 5%. In the paper, the basic reaction as well as material properties will be discussed

Organic-inorganic hybrid materials processing and applications

Hybrid materials as inorganic-organic nanostructured composites require tailored surface chemistry in order to obtain a homogeneous distribution of the nanoparticles in the matrix. For this reason, nanoparticles with organic functions have been synthesized, first, to provide the desired æ-potential at a given pH value, second, to avoid irreversible agglomeration due to the spacing effect, and third, to provide the appropriate surface chemistry. I could be shown that using this approach, it is possible to switch the ζ-potential of SiO2 nanoparticles from a negative to a positive potential at neutral and to bind DNA fragments to the particles for an effective transfection into cells. Other examples show that nanoparticles (TiO2, SiO2) coated with epoxy and methacryloxy groupings can be used as coating sol for the fabrication of thin films with green densities up to 67% by volume only by photochemical crosslinking of the polymerizable groupings. Using this approach, interference layers have been fabricated on transparent plastics. In soft matrices, these particles permit to establish appropriate ζ-potentials and in electric fields by electrophoresis, it was possible to up-concentrate them to form gradient index optics. The investigations show that surface chemistry-tailored nanoparticles are a useful tool for the fabrication of nanocomposite hybrids

Sol-gel derived nanoparticles and processing routes to ceramics and composites

Highly crystalline nanoparticles from Y-Zr02 and FeOx have been prepared by microemulsion with subsequent solvothermal treatment and by precipitation processes. In both cases, aqueous based intermediates have been prepared which have been surface-modified by carboxylic acids and ammosilane. The surface modification prevents the formation of hard agglomerates of the nanoparticles (6-8 ran) completely and provides complete redispersibility. Low sintering compacts and nanocomposites have been prepared, and first results for using the FeOx nanoparticles for medical applications have been obtained