Browsing by Subject "DIMETHYL-SULFOXIDE"

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  • Stape, Thiago Henrique Scarabello; Seseogullari-Dirihan, Roda; Tjäderhane, Leo; Abunas, Gabriel; Marcondes Martins, Luis Roberto; Tezvergil-Mutluay, Arzu (2018)
    In dentistry, the wet-bonding approach relies on water to maintain demineralized collagen expanded for proper resin infiltration; nevertheless, hydrolytic instability of the resin-dentin interface is inevitable with current bonding techniques. Considering dimethyl sulfoxide's (DMSO) ability to "biomodify" collagen and precipitate enzymes, the aim was to test whether the use of DMSO would permit adequate resin bonding to H3PO4-etched dehydrated dentin and assess its impact on collagen degradation by host-derived enzymes. Etched dentin surfaces from extracted sound human molars were randomly bonded in wet or dry conditions using aqueous or ethanolic DMSO solutions as pretreatments and bonding resins with or without DMSO. Bonded teeth were sectioned into resin-dentin slabs for confocal in situ zymography and beams for microtensile bond strength test. Demineralized powdered dentin was incubated in the tested DMSO -media and a hydroxyproline assay evaluated dissolution of collagen peptides. Zymography was performed on protein extracts obtained from dry and wet H3PO4-ecthed dentin powder treated with the DMSO- media. The correlative biochemical analysis demonstrated that reduction of water content during dentin hybridization by the innovative dry-bonding approaches with DMSO is effective to inactivate host-derived MMP-2 and MMP-9 and thus reduce collagen degradation while simultaneously optimizing resin-dentin bonding.
  • Ferreira, Daniela C.; Oliveira, Mayara L.; Bioni, Thais A.; Nawaz, Haq; King, Alistair W. T.; Kilpeläinen, Ilkka; Hummel, Michael; Sixta, Herbert; El Seoud, Omar A. (2019)
    The efficiency of mixtures of ionic liquids (ILs) and molecular solvents in cellulose dissolution and derivatization depends on the structures of both components. We investigated the ILs 1-(1-butyl)-3-methylimidazolium acetate (C(4)MeImAc) and 1-(2-methoxyethyl)-3-methylimidazolium acetate (C(3)OMeImAc) and their solutions in dimethyl sulfoxide, DMSO, to assess the effect of presence of an ether linkage in the IL side-chain. Surprisingly, C(4)MeImAc-DMSO was more efficient than C(3)OMeImAc-DMSO for the dissolution and acylation of cellulose. We investigated both solvents using rheology, NMR spectroscopy, and solvatochromism. Mixtures of C(3)OMeImAc-DMSO are more viscous, less basic, and form weaker hydrogen bonds with cellobiose than C(4)MeImAc-DMSO. We attribute the lower efficiency of C(3)OMeImAc to "deactivation" of the ether oxygen and C2-(H) under bar of the imidazolium ring due to intramolecular hydrogen bonding. Using the corresponding ILs with C2-(CH3) under bar instead of C2-(H) under bar, namely, 1-butyl-2,3-dimethylimidazolium acetate (C(4)Me(2)ImAc) and 1-(2-methoxyethyl)-2,3-dimethylimidazolium acetate (C(3)OMe(2)ImAc) increased the concentration of dissolved cellulose; without noticeable effect on biopolymer reactivity.
  • Kasparyan, Gari; Poojari, Chetan; Rog, Tomasz; Hub, Jochen S. (2020)
    Itraconazole is a triazole drug widely used in the treatment of fungal infections, and it is in clinical trials for treatment of several cancers. However, the drug suffers from poor solubility, while experiments have shown that itraconazole delivery in liposome nanocarriers improves both circulation half-life and tissue distribution. The drug release mechanism from the nanocarrier is still unknown, and it depends on several factors including membrane stability against defect formation. In this work, we used molecular dynamics simulations and potential of mean force (PMF) calculations to quantify the influence of itraconazole on pore formation over lipid membranes, and we compared the effect by itraconazole with a pore-stabilizing effect by the organic solvent dimethyl sulfoxide (DMSO). According to the PMFs, both itraconazole and DMSO greatly reduce the free energy of pore formation, by up to similar to 20 kJ mol(-1). However, whereas large concentrations of itraconazole of 8 mol % (relative to lipid) were required, only small concentrations of a few mole % DMSO (relative to water) were sufficient to stabilize pores. In addition, itraconazole and DMSO facilitate pore formation by different mechanisms. Whereas itraconazole predominantly aids the formation of a partial defect with a locally thinned membrane, DMSO mainly stabilizes a transmembrane water needle by shielding it from the hydrophobic core. Notably, the two distinct mechanisms act cooperatively upon adding both itraconazole and DMSO to the membrane, as revealed by an additional reduction of the pore free energy. Overall, our simulations reveal molecular mechanisms and free energies of membrane pore formation by small molecules. We suggest that the stabilization of a locally thinned membrane as well as the shielding of a transmembrane water needle from the hydrophobic membrane core may be a general mechanism by which amphiphilic molecules facilitate pore formation over lipid membranes at sufficient concentrations.