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Department: search.filters.department.Department of PhysicsSubject: search.filters.subject.Chemistry, physical and theoretical

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Now showing 1 - 5 of 5
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    Determination of the wavelength-dependent photothermal conversion efficiency of photosensitizers for photothermal therapy: application to Ag2S-glutathione quantum dots
    (Amer Chemical Soc, 2021) Department of Physics; N/A; N/A; Department of Chemistry; Sennaroğlu, Alphan; Khan, Minahil; Hashemkhani, Mahshid; Acar, Havva Funda Yağcı; Faculty Member; PhD Student; PhD Student; Faculty Member; Department of Physics; Department of Chemistry; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; 23851; N/A; N/A; 178902
    Nanoparticles have become popular photosensitizers for photothermal therapy (PTT), as they can be targeted to specific cancer tissues and deliver a chemotherapeutic drug, providing a multimodal therapeutic approach. Photothermal conversion efficiency of nanoparticles is critical in the assessment of their therapeutic use in PTT. We describe an accurate calorimetric method for the determination of the photothermal conversion efficiency of nanoparticles in solution. A tightly focused laser beam was used to irradiate a cuvette containing a solution of silver sulfide-glutathione quantum dots (Ag2S-GSH QDs), and the maximum steady-state temperature rise was measured with an infrared camera. The data were analyzed using two different photothermal conversion efficiencies, the intrinsic and external conversion efficiencies, to relate the induced heating power of the nanoparticles to the absorbed and incident optical powers, respectively. Measurements with a tunable Ti3+:sapphire laser showed that the intrinsic photothermal conversion efficiency of Ag(2)SGSH QDs exceeded 91% over the 720-810 nm wavelength range. The method was also used to analyze poly(acrylic acid)-coated superparamagnetic iron oxide nanoparticles (PAA/SPIONs), and the intrinsic photothermal conversion efficiency was determined to be 83.4% at 810 nm. This approach is useful for the evaluation of various potential nanoparticles for photothermal therapy applications.
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    Investigation of the hydrogen gas sensing properties of nanoporous Pd alloy films based on AAO templates
    (Elsevier, 2011) Öztürk, Sadullah; Kılınç, Necmettin; Öztürk, Zafer Ziya; Department of Physics; Taşaltın, Nevin; Researcher; Department of Physics; College of Sciences; 220956
    In this study, the hydrogen sensing properties of nanoporous Pd-Ag and Pd-Cu alloy films based on anodic aluminum oxide (AAO) templates were investigated at various temperatures (25-100 degrees C) and hydrogen with concentrations in the range between 250 and 5000ppm in high purity nitrogen to determine the temperature-sensitivity relationship. A hexagonally shaped AAO template of approximately 50nm in diameter and 10 mu m in length was fabricated as a substrate for supporting a nanoporous Pd alloy film with an approximate thickness of 80 nm. The morphologies of the AAO template and the Pd alloy films were studied by scanning electron microscopy (SEM). The hydrogen sensing properties of the nanoporous Pd-Ag and Pd-Cu alloy films were measured using a transient resistance method. The sensor responses of the nanoporous Pd-Ag and Pd-Cu films on the AAO template were better than the traditional Pd-Ag and Pd-Cu thin film sensors; the sensitivities of the sensors were approximately 1.6% and 1.2%, respectively, for 1000ppm H(2), and the detection limit was 250ppm at room temperature. The highest sensitivity was measured at room temperature for all alloy nanoporous sensors, and the sensitivity of the Pd-Ag nanoporous alloy was higher than that of the Pd-Cu nanoporous alloy.
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    Motion of single terrylene molecules in confined channels of poly(butadiene)-poly(ethylene oxide) diblock copolymer
    (Amer Chemical Soc, 2009) N/A; Department of Physics; Department of Chemistry; Yorulmaz, Mustafa; Kiraz, Alper; Demirel, Adem Levent; Master Student; Faculty Member; Faculty Member; Department of Physics; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; 22542; 6568
    The motion of terrylene probe molecules in confined PB channels of an asymmetric PB-PEO diblock copolymer has been investigated by single molecule tracking. The one-dimensional diffusion coefficients were found to be significantly smaller and had a narrower distribution compared to two-dimensional diffusion coefficients in PB. The trajectories of some single molecules showed unusual behavior of directed motion where mean square displacement had a parabolic dependence oil lag time. The likely origin of this behavior is discussed in terms of local variations in the PB channel width and the resulting change in the local density. The results show the effect of nonuniformities and heterogeneities in the channels on the motion of single molecules and demonstrate the sensitivity of single molecule tracking in characterizing self-assembled block copolymer morphologies.
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    POLY 708-Photoluminescent rare-earth ion containing silicone copolymers
    (Amer Chemical Soc, 2006) Department of Chemistry; Department of Chemistry; N/A; Department of Physics; Yılgör, İskender; Yılgör, Emel; Demirbaş, Ümit; Sennaroğlu, Alphan; Kurt, Adnan; Tezgel, Arife Özgül; Faculty Member; Researcher; Master Student; Faculty Member; Teaching Faculty; Undergraduate Student; Department of Chemistry; Department of Physics; College of Sciences; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; 24181; N/A; 20328; 23851
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    Single-molecule fluorescence of terrylene embedded in anthracene matrix: a room temperature study
    (Elsevier Science Bv, 2012) N/A; Department of Physics; Yüce, Mehdi Yavuz; Kiraz, Alper; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 22542
    We characterized room-temperature fluorescence properties of single terrylene molecules embedded in anthracene thin films that were prepared by spin-coating on glass substrates. Our results show that terrylene molecules embedded in anthracene matrix are oriented nearly parallel to the substrate. Typical measured fluorescence lifetime of terrylene was 3.6 ns and photon count rate at saturation was 750 kHz. Our analyses of 104 molecules indicate that we can detect on average 1.6 x 10(6) photons from a single terrylene molecule before it photobleaches. These results make terrylene-anthracene a promising guest-host system for room temperature single molecule experiments.