RESUMO
This paper describes the synthesis, functionalization, and multitechnique analysis of magnetic nanoparticles. The synthetic method involves the covering of a magnetite nucleus by a silica layer and the further functionalization with different fluorophores via a cross-linker molecule. All synthetic intermediates were analyzed by fluorescence spectroscopy and AC magnetic susceptibility. For one of the considered molecules, a further investigation with STEM, EDXS, and DLS has been conducted in order to validate the proposed magnetic results. The comparison between the two techniques is used to ensure a complete characterization of the product confirming the success of the synthesis. By comparing the magnetic and the fluorescence measurements, we also demonstrate the effectiveness of AC susceptibility as a robust and versatile technique to follow the synthesis of complex magnetic nanostructures regardless of the nature of the functionalization.
Assuntos
Magnetismo , Nanoestruturas , Microscopia Eletrônica de Varredura , Espectroscopia de Prótons por Ressonância Magnética , Espectrometria de FluorescênciaRESUMO
Natural gadolinium is the strongest neutron-absorbing element and neutron diffraction studies of Gd-containing materials rely on the use of either enriched Gd isotopes or short neutron wavelengths where the absorption is weaker but, unfortunately, the neutron flux is also weak. We have employed a new sample-mounting technique to obtain neutron powder diffraction patterns from the intermetallic compound Gd(3)Ag(4)Sn(4) containing natural Gd, at a neutron wavelength of â¼ 2.37 Å where there is much greater flux. Here, we report the magnetic structure of Gd(3)Ag(4)Sn(4). The magnetic ordering temperature is 28.8(2) K. At 2.8 K the Gd(4e) sublattice is antiferromagnetically ordered along the crystal c-axis, commensurate with the crystal lattice. The Gd(2d) sublattice is also ordered along the c-axis but its magnetic structure is incommensurate with the crystal lattice.
RESUMO
The concept of drug monitoring is generally accepted for toxic drugs and for some particular pathological states. However its basis and its limits are still controversial. This paper outlines under which circumstances drug monitoring is of absolute necessity. This paper also deals with pharmacokinetics, i.e. the measurement of drug concentration as a tool in drug monitoring. Finally it tries to forecast future developments in this field using the analysis of receptors, found in blood cells, as probes of tissue receptors.