Browsing by Subject "Molecular oxygen"
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Item Open Access Functional electrospun polystyrene nanofibers incorporating α-, β-, and γ-cyclodextrins: Comparison of molecular filter performance(2010) Uyar, Tamer; Havelund, R.; Hacaloglu, J.; Besenbacher, F.; Kingshott, P.Electrospinning has been used to successfully create polystyrene (PS) nanofibers containing either of three different types of cyclodextrin (CD); α-CD, β-CD, and γ-CD. These three CDs are chosen because they have different sized cavities that potentially allow for selective inclusion complex (IC) formation with molecules of different size or differences in affinity of IC formation with one type of molecule. The CD containing electrospun PS nanofibers (PS/CD) were initially characterized by scanning electron microscopy (SEM) to determine the uniformity of the fibers and their fiber diameter distributions. X-ray photoelectron spectroscopy (XPS) was used to quantitatively determine the concentration of each CD on the different fiber surfaces. Static time-of-flight secondary ion mass spectrometry (static-ToF-SIMS) showed the presence of each type of CD on the PS nanofibers by the detection of both the CD sodium adduct molecular ions (M + Na+) and lower molecular weight oxygen containing fragment ions. The comparative efficiency of the PS/CD nanofibers/nanoweb for removing phenolphthalein, a model organic compound, from solution was determined by UV-vis spectrometry, and the kinetics of phenolphthalein capture was shown to follow the trend PS/α-CD > PS/β-CD > PS/γ-CD. Direct pyrolysis mass spectrometry (DP-MS) was also performed to ascertain the relative binding strengths of the phenolphthalein for the CD cavities, and the results showed the trend in the interaction strength was β-CD > γ-CD > α-CD. Our results demonstrate that nanofibers produced by electrospinning that incorporate cyclodextrins with different sized cavities can indeed filter organic molecules and can potentially be used for filtration, purification, and/or separation processes. © 2010 American Chemical Society.Item Open Access Near-IR absorbing BODIPY derivatives as glutathione-activated photosensitizers for selective photodynamic action(Wiley-VCH Verlag, 2014) Turan, I. S.; Cakmak, F. P.; Yildirim, D. C.; Cetin Atalay, R.; Akkaya, E. U.Enhanced spatiotemporal selectivity in photonic sensitization of dissolved molecular oxygen is an important target for improving the potential and the practical applications of photodynamic therapy. Considering the high intracellular glutathione concentrations within cancer cells, a series of BODIPY-based sensitizers that can generate cytotoxic singlet oxygen only after glutathione-mediated cleavage of the electron-sink module were designed and synthesized. Cell culture studies not only validate our design, but also suggest an additional role for the relatively hydrophobic quencher module in the internalization of the photosensitizer.Item Open Access Thinking outside the silicon box: molecular and logic as an additional layer of selectivity in singlet oxygen generation for photodynamic therapy(2009) Ozlem, S.; Akkaya, E. U.A simple derivative of a well-known dye bodipy appears to be a satisfactory sensitizer for singlet oxygen. Moreover, the rate of singlet oxygen generation can be modulated by two cancer-related cellular parameters, sodium ion concentration and acidity. Singlet oxygen generation rate is maximal when sodium ions and an organic acid were added. The operation of this molecular automaton follows AND logic, which introduces an additional layer of selectivity in the photodynamic action of the reagent. It should also be noted that in this system sensing, computing and actuating functions are realized within a single molecule. Copyright © 2008 American Chemical Society.