RESUMEN
Magnetite nanoparticles (Chemicell SiMAG-TCL) were characterized by SQUID-relaxometry, susceptometry, and TEM. The magnetization detected by SQUID-relaxometry was 0.33% of that detected by susceptometry, indicating that the sensitivity of SQUID-relaxometry could be significantly increased through improved control of nanoparticle size. The relaxometry data were analyzed by the moment superposition model (MSM) to determine the distribution of nanoparticle moments. Analysis of the binding of CD34-conjugated nanoparticles to U937 leukemia cells revealed 60,000 nanoparticles per cell, which were collected from whole blood using a prototype magnetic biopsy needle, with a capture efficiency of >65% from a 750 µl sample volume in 1 minute.
RESUMEN
Four new one-dimensional materials and one dimer complex based on the linkage of [Nb6O19] clusters and [CuLx] (L=ethylenediamine (en), NH3, H2O) assemble under ambient conditions. These phases include the following: Rb4[Cu(en)2(H2O)2]3[(Nb6O19H2)2Cu(en)2].24H2O (1), space group P; [Cu(en)2(H2O)2]2[(Nb6O19H2)Cu(en)2].14H2O (2), space group P; Rb2[Cu(NH3)2(H2O)4][Cu(NH3)4(H2O)2]2{[Nb6O19][Cu(NH3)]2}(2).6H2O (3), space group P; {[Nb6O19][Cu(NH3)2(H2O)]2[Cu(H2O)4]2}.3H2O (4), space group P2/n; and {[Nb6O19][Cu(NH3)2(H2O)]2[Cu(H2O)4]2} (5), space group C2/m. All structures have been solved by single-crystal methods, and compounds 1-5 were characterized by thermogravimetric analysis, Fourier transform IR, chemical analysis, and magnetic measurements. It has been demonstrated that the conformation, charge, and geometry of the [Nb6O19]-[CuLx] chains can be modulated by varying the type and amount of the [CuLx]2+ species. The charge balance is provided by mixed Rb+/[CuLx]2+ or [CuLx]2+ cations only for structures 1-3, whereas 4 and 5 are neutral chains with no counterions. There are weak antiferromagnetic Cu2+-Cu2+ interactions in all phases. Compounds 2-5 represent the first examples in which the [Nb6O19] Lindqvist ion forms extended solids rather than dimers or decorated monomers when reacted with transition-metal, cationic complexes.