Single-walled carbon nanotubes affect the expression of genes associated with immune response in normal human astrocytes.

The effect of single-walled carbon nanotubes (SWCNTs) on the expression of a subset of immune response, apoptosis and cell proliferation -associated genes was studied in normal human astrocytes (line NHA/TS). In the cells treated with SWCNTs (2, 10 and 50 ng/ml of medium for 24 h) we observed a strong dose-dependent down-regulation of the expression of a cell surface glycoproteins HLA-DRA (major histocompatibility complex, class II, DR alpha) and HLA-DRB1. At the same time, the expression of HLA-F (major histocompatibility complex, class I, F), LMNB1 (lamin B1), and HTRA1 (high temperature requirement A1) genes as well as the level of miR-190b and miR-7 was up-regulated in NHA/TS subjected to different concentrations of SWCNTs. After 24 h of treatment with SWCNTs we detected a dose-dependent suppression of PHLDA2 (pleckstrin homology-like domain, family A, member 2) gene expression in these cells. Obtained data show that SWCNTs may affect an immune response, in particular through suppression of HLA-DRA and HLA-DRB1 gene expressions and that miR-190b and miR-7 possibly participated in this suppression. Deregulation of lamin B1 expression indicates the possibility of alterations in genome stability following treatment of astrocytes with SWCNTs. Thus, more caution is needed in biomedical application of SWCNTs.

Complexation of late transition metal(II) ions (M = Co, Ni, Cu, and Zn) by a macrocyclic thiacrown ether studied by means of electrospray ionization mass spectrometry.

Electrospray ionization mass spectrometry (ESI-MS) is used to probe the metal-binding selectivity of a macrocyclic thiacrown ether (C(44)H(32)S(20)) towards Co(II), Ni(II), Cu(II), and Zn(II). In homogeneous 1:1 v/v methanol/dichloromethane solutions, it is found that the thia ligand very selectively binds traces of copper even in the presence of an excess of the other metal ions. The large selectivity is ascribed to the redox-active nature of copper which enables a reduction from Cu(II) to Cu(I), occurring upon ESI-MS, whereas Co(II), Ni(II) and Zn(II) cannot undergo similar redox reactions.

Can electrospray mass spectrometry quantitatively probe speciation? Hydrolysis of uranyl nitrate studied by gas-phase methods.

Electrospray ionization of uranyl nitrate dissolved in water generates gaseous species containing either hydroxo-uranyl [UO(2)(OH)](+) or nitrato-uranyl [UO(2)(NO(3))](+) contact ion pairs solvated by up to four water molecules. Furthermore, uranyl clusters of the general type [U(m)O(2m)(X,Y)(2m-1)(H(2)O)(n)](+) (X,Y = OH, NO(3)) with m = 1-5 and n = 2-4 are formed. Collision-induced dissociation experiments are used to probe the structures and the stoichiometries of the uranyl ions generated. A detailed investigation of the concentration-dependent behavior of the formed gaseous uranyl complexes reveals a preference for nitrate- over hydroxide-containing species with increasing concentration of the sprayed solution. This behavior reflects changes in the pH value of the bulk solutions that can be attributed to solvolysis of UO(2)(2+) in water. Further, the tendency for generation of polynuclear cluster ions is amplified with increasing concentration and can be explained by a mechanism which involves the association of cations present in solution with neutral species such as UO(2)(OH)(2), UO(2)(OH)(NO(3)), and UO(2)(NO(3))(2). The observed dependences of the cluster-ion intensities in the mass spectra from the concentration of the solutions fed to the electrospray source are used to suggest a scheme for a quantitative correlation between the gas-phase and solution-phase data. The results inter alia indicate that the effective concentrations of the spraying solution can be several orders of magnitude larger than those of the feed solutions entering the electrospray ionization source.

Study of the interactions of sodium thiocyanate, potassium thiocyanate and ammonium thiocyanate in water+N,N-dimethylformamide mixtures by Raman spectroscopy.

Raman spectra of water+N,N-dimethylformamide (DMF) mixtures and their solutions with NaNCS, KNCS and NH(4)NCS were obtained. The bands of nu(CO) stretching, delta(OCN) bending, r(CH(3)) rocking and nu(N-CH)(3)) stretching of the DMF molecule with and without salts were studied. The dependence of the vibration frequencies and Raman intensities of the bands on the composition of the mixed solvent was discussed. The change of the band frequencies as a result of the presence of the salts and the solvation of the cations by the solvent molecules was examined. The stronger cation solvation by the aprotic solvent molecules instead of the water molecules in DMF concentrated solutions was discussed. The nu(CN) and nu(CS) vibrations of the SCN(-) ions were observed as a function of the cation present and the solvent composition. The presence of the SCN(-) ions as "free", contact ion pairs, or solvent separated pairs, was discussed.

Solvation of copper(II) sulfate in binary water/N,N-dimethylformamide mixtures: from the solution to the gas phase.

The solvation of copper(II) sulfate in binary mixtures of water and N,N-dimethylformamide (DMF) is studied by a combined approach using electrochemical studies in solution and a mass spectrometric assay of the solvated ions formed from these solutions upon electrospray ionization (ESI). In the condensed phase, the limiting transference numbers (t(+/-)(o)) and the apparent ion association constants (K(A)'s) of CuSO(4) have been determined in water/DMF solutions at 20 degrees C. The t(+)(o) values decrease with increasing DMF content, demonstrating a gradual solvation of Cu(2+) by DMF molecules. The association constants indicate that aggregation becomes more pronounced as the DMF content increases. In order to achieve complementary insight, the intrinsic interactions among the ions and solvent molecules are investigated in gas-phase experiments of the CuSO(4)/water/DMF system using ESI mass spectrometry. Under the conditions used, the dications [Cu(DMF)(n)](2+) (n = 3-6), [Cu(2)(DMF)(n)SO(4)](2+) (n = 2-7), and [Cu(3)(DMF)(n)(SO(4))(2)](2+) (n = 2-7), and the monocations [Cu(OH)(DMF)(n)](+), [Cu(DMF)(n)(HSO(4))](+) (both, n = 1-3), and [Cu(DMF)(n)](+) (n = 1, 2), are formed as the leading copper-containing cations. Likewise, polynuclear copper clusters observed in the anion ESI spectra support partial aggregation occurring in solution. The gas-phase studies clearly support the conclusions that (i) DMF is a highly preferred ligand for CuII in comparison to water and that (ii) DMF supports ion association for which the mass spectrometric data suggest the formation of polynuclear copper clusters.

Competitive complexation of gaseous Mn(II) by 1,10-phenanthroline, 2,2'-bipyridine, and 4,5-diazafluorene.

Complexes of Mn(II) with 1,10-phenanthroline (phen) and 2,2'-bipyridine (bipy) are investigated by means of electrospray ionization (ESI) mass spectrometry. Under the conditions used, [MnL(n)]2+ with n = 2 and 3, [MnL(n)Cl]+ with n = 0-2, and [Mn2L(n)Cl3]+ with n = 2 and 3 are produced (where L = phen or bipy). The collision-induced dissociation (CID) spectra of the mass-selected ions show various dissociation pathways, most notable among them is the reduction of the ligated Mn(II) to Mn(I) by intracomplex electron transfer. CID experiments of mixed-ligand complexes formed upon ESI from solutions which contain both phen and bipy exhibit preferential eliminations of bipy, indicating that bipy is a significantly weaker ligand for Mn(II) than phen. This effect is mainly attributed to the flexibility of the bipy ligand concomitant with thermodynamic control in ion dissociation. To support this hypothesis, mixed complexes with some methylated derivatives as well as those containing 4,5-diazafluorene (daf) are examined also. Interestingly, the differences between the ligands diminish in charge-separation reactions of dicationic Mn(II) complexes, due to the joined operation of thermodynamic as well as kinetic effects. In addition, the complexes [Mn(bipy)]+, [Mn(phen)]+, [Mn(bipy)]2+, [Mn(phen)]2+, and [Mn(bipy)(phen)]2+ are computed using the mPW1PW91 hybrid density functional along with the Stuttgart-Cologne-type pseudopotential and basis-set suite, and relative energies for charge-separation reactions and losses of neutral ligands are evaluated.