Synthesis and characterization of sulfated Gal-ß-1,3/4-GlcNAc disaccharides through consecutive protection/glycosylation steps.

We have developed an expeditious procedure to yield large amounts of orthogonally protected Gal-ß1,3/4-GlcNAc, which allowed for the systematic introduction of a sulfate group onto the C3/C6 positions of Gal and/or the C6 position of GlcNAc. In particular, the disaccharide precursors were prepared in five or six steps and high overall yield from para-tolyl-6-O-tert-butyldiphenylsilyl-1-thio-ß-D-galactopyranoside. After deprotection and sulfation steps, the final products were characterized by using several NMR methods to unambiguously confirm the location of each introduced sulfate group and they were examined for their binding specificity of human galectin-1 and galectin-8.

Molecular ordering of mixed surfactants in mesoporous silicas: a solid-state NMR study.

The use of mixed surfactants in the synthesis of mesoporous silica nanoparticles (MSNs) is of importance in the context of adjusting pore structures, sizes and morphologies. In the present study, the arrangement of molecules in micelles produced from a mixture of two surfactants, cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB) was detailed by solid-state NMR spectroscopy. Proximities of methyl protons in the trimethylammonium headgroup of CTAB and protons in the pyridinium headgroup of CPB were observed under fast magic angle spinning (MAS) by (1)H-(1)H double quantum (DQ) MAS NMR and NOESY. This result suggested that CTAB and CPB co-exist in the pores without forming significant monocomponent domain structures. (1)H-(29)Si heteronuclear correlation (HETCOR) NMR showed that protons in the headgroups of CTAB are in closer proximity to the silica surface than those in the CPB headgroups. The structural information obtained in this investigation leads to better understanding of the mechanisms of self-assembly and their role in determining the structure and morphology of mesoporous materials.

Synthesis of metal ion-histidine complex functionalized mesoporous silica nanocatalysts for enhanced light-free tooth bleaching.

Several metal ion-histidine complex functionalized mesoporous silica nanoparticles (MSN) were synthesized and utilized as efficient catalysts for enhanced and light-free tooth bleaching. Fe(II), Mn(II), and Cu(II) ions were successfully immobilized in histidine-functionalized MSN and their catalytic abilities against discoloration of a dye (Orange II) in both test tubes and extracted tooth models were compared and discussed. Through direct observation of test tubes and calculation of mean color changes of extracted teeth we concluded that Fe(II)-his-MSN exhibited better catalytic competence than Mn(II)-his-MSN and Cu(II)-his-MSN because of its intrinsic redox ability. In test tubes Orange II was completely degraded within 6 h when Fe(II)-his-MSN was used as the catalyst. For the extracted tooth model the presence of Fe(II)- or Mn(II)-his-MSN significantly enhanced the efficacy of tooth bleaching for three regions, the enamel, outer dentin, and inner dentin, of stained teeth compared with H(2)O(2) alone. Furthermore, unlike current tooth bleaching techniques that need an LED or laser to catalyze H(2)O(2) bleaching, we demonstrated a light-free tooth bleaching system using Fe(II)-his-MSN as an efficient and reliable catalyst.