In vitro experiments have shown the great potential of magnetic nanocarriers for multimodal imaging diagnosis and non-invasive therapies. However, their extensive clinical application is still jeopardized by a fast retention in the reticuloendothelial system (RES). The other issue that restrains their potential performance is slow degradation and excretion, which increases their risks of toxicity. We report a promising case in which multicore iron oxide nanoparticles coated with a poly(4-vinylpyridine) polyethylene glycol copolymer show low RES retention and high urinary excretion, as confirmed by single photon emission computerized tomography (SPECT), gamma counting, magnetic resonance imaging (MRI) and electron microscopy (EM) biodistribution studies. These iron oxide-copolymer nanoparticles have a high PEG density in their coating which may be responsible for this effect. Moreover, they show a clear negative contrast in the MR imaging of the kidneys. These nanoparticles with an average hydrodynamic diameter of approximately 20 nm were nevertheless able to cross the glomerulus wall which has an effective pore size of approximately 6 nm. A transmission electron microscopy inspection of kidney tissue revealed the presence of iron containing nanoparticle clusters in proximal tubule cells. This therefore makes them exceptionally useful as magnetic nanocarriers and as new MRI contrast agents for the kidneys.

The crystal structure, thermal vibrations and electron density of L-arginine phosphate monohydrate (formally C6H15N4O2 +.H2PO4 −.H2O) have been analysed using 130 K single-crystal X-ray diffraction data to a resolution of (sin θ/λ)max = 1.20 Å−1. A multipolar pseudo-atom density model was fitted against the 6805 observed data with I > 3σ(I), [R(F) = 0.016,Rw (F) = 0.014, S = 1.39] in order to map the static valence-electron density distribution. Positional and thermal vibration parameters for H atoms were taken from neutron diffraction results. A comparison between the electron density ρ(r), ∇2 ρ(r) and the electrostatic potential calculated from X−X and X−(X + N) refinements shows that reliable results may be obtained from X−X data only.

A Raman spectroscopic study of aqueous solutions of KH,P04 as a function of concentration and temperature has been made. Attention is focused on the analysis of the bands arising from the internal modes of the H,P04-anions. The band profile of these internal modes has been analysed by a Fourier transform self-deconvolution method which allowed quantitative information about phosphate dimerization to he obtained. The results seem to indicate the existence of two different configurations for the dimers. The association constant for each dimer and their thermodynamic parameters were obtained from the spectroscopic data.

The electron density of L-histidinium dihydrogen orthophosphate orthophosphoric acid has been determined from X-ray and neutron diffraction data at low temperature (120 K). Topological analysis of the electron density has been used to analyse the effect of the multipolar refinement strategy on the electron-density model in the hydrogen-bonding regions. The electron density at low temperature has also been used to acquire high-quality experimental thermal parameters at room temperature using the transferability principle. Molecular vibrations, TLS and normal mode analysis are discussed and studied at both temperatures.

The problem of removing the characteristic parasitic errors of the high-accuracy universal polarimeter method in a linearly birefringent and optically active crystal section is examined. The use of constant parasitic errors typical of each particular polarimetric system is shown to be inappropriate. The parasitics should preferably be determined in each measurement process, since the instrumental parasitics depend not only on the optical and mechanical elements of the experimental system (polarizers, rotators, detection unit etc.), but on sample quality, alignment of the system, and even in many cases on exactly where the light beam passes through the sample. Thus, measurements with different samples give different values of parasitic errors. Such instrumental parasitics can be held within the same order of magnitude for different samples ($10 À4 ) if they are of good optical quality. However, the parasitics are increased by an order of magnitude ($10 À3 ) when the samples are of moderate or bad optical quality. Optical anisotropy properties as coef®cients of thermal variation of the birefringence of KDC and KDP single crystals and the optical activity of KDP at 632.8 nm wavelength are obtained, in the ranges from room temperature to 353 K and to 373 K, respectively.

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Abstract. In this study we present a morphological approach in observing the interaction of cationic magnetic nanoparticles with A-549 cells (human lung adenocarcinoma). Under our experimental conditions, nanoparticles easily penetrated cells and were observed in vivo, using bright light microscopy. In fixed cells, nanoparticles remained inside cells, showing quantity and distribution patterns similar to those in unfixed cells. The presence of nanoparticles did not affect cell viability or the morphologic parameters assessed. We determined the potential internalization mechanism of nanoparticles into cells using endocytosis inhibitors. The results suggest that nanoparticles used in this study penetrate A-549 cells mainly through a macropinocytosis process.

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