PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7645
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Article Citation - WoS: 3Citation - Scopus: 3Green Fabrication of Lanthanide-Doped Hydroxide-Based Phosphors: Y(oh)(3):eu3+ Nanoparticles for White Light Generation(Beilstein-Institut Zur Forderung der Chemischen Wissenschaften, 2019) Güner, Tuğrul; Kuş, Anılcan; Özcan, Mehmet; Genç, Aziz; Şahin, Hasan; Demir, Mustafa MuammerPhosphors can serve as color conversion layers to generate white light with varying optical features, including color rendering index (CRI), high correlated color temperature (CCT), and luminous efficacy. However, they are typically produced under harsh synthesis conditions such as high temperature, high pressure, and/or by employing a large amount of solvent. In this work, a facile, water-based, rapid method has been proposed to fabricate lanthanide-doped hydroxide-based phosphors. In this sense, sub-micrometer-sized Y(OH)(3):Eu3+ particles (as red phosphor) were synthesized in water at ambient conditions in <= 60 min reaction time. The doping ratio was controlled from 2.5-20 mol %. Additionally, first principle calculations were performed on Y(OH)(3):Eu3+ to understand the preferable doping scenario and its optoelectronic properties. As an application, these fabricated red phosphors were integrated into a PDMS/YAG:Ce3+ composite and used to generate white light. The resulting white light showed a remarkable improvement (approximate to 24%) in terms of luminous efficiency, a slight reduction of CCT (from 3900 to 3600 K), and an unchanged CRI (approximate to 60) as the amount of Y(OH)(3):Eu3+ was increased.Article Citation - WoS: 18Citation - Scopus: 14Optimization and Performance of Nitrogen-Doped Carbon Dots as a Color Conversion Layer for White-Led Applications(Beilstein-Institut Zur Forderung der Chemischen Wissenschaften, 2019) Güner, Tuğrul; Yüce, Hürriyet; Taşçıoğlu, Didem; Şimşek, Eren; Savacı, Umut; Genç, Aziz; Demir, Mustafa MuammerIn this study, green-emitting nitrogen-doped carbon dots (N-CDots) were synthesized and incorporated into drop-cast composite films for use as color conversion layers in a white-LED configuration to generate white light. In order to resolve the red deficiency of this configuration, a commercial red phosphor was integrated into the system. Moreover, the N-CDots were also processed into polymer/N-CDot composite fibers, for which we determined the amount of N-CDots that yielded adequate white-light properties. Finally, we showed that white light with excellent properties could be generated by employing both of the fabricated N-CDot composites either as drop-cast films or composite fibers. Hence, N-CDots provide a promising alternative to inorganic phosphors that are commonly employed in white-LED configurations.Article Citation - WoS: 36Citation - Scopus: 42Protoporphyrin Ix-Loaded Magnetoliposomes as a Potential Drug Delivery System for Photodynamic Therapy: Fabrication, Characterization and in Vitro Study(Elsevier Ltd., 2016) Başoğlu, Harun; Bilgin, Mehmet Dinçer; Demir, Mustafa MuammerProtoporphyrin IX (PpIX) is a well-known photosensitizer that has great potential for use in photodynamic therapy (PDT). However, aggregation behavior of PpIX in neutral water makes it inappropriate for physiological studies. PpIX-loaded magnetoliposomes (MLs) were fabricated to increase PpIX biocompatibility. PpIX-loaded ML physical properties were characterized, and PpIX-loaded ML drug release behavior was investigated under the influence of an external magnetic field and heat. Toxicity and photodynamic effects of the complex were also examined using in vitro experiments with MCF-7 human breast cancer cells. The magnetoliposomes were prepared with DPPC, DSPE-PEG2000 lipids and Fe3O4 nanoparticles. The toxicity and in vitro photodynamic effects of the PpIX-loaded MLs at various concentrations were studied using the MCF-7 cell line.Article Citation - WoS: 28Citation - Scopus: 29Formation of Pseudoisocyanine J-Aggregates in Poly(vinyl Alcohol) Fibers by Electrospinning(American Chemical Society, 2009) Demir, Mustafa Muammer; Özen, Bengisu; Özçelik, SerdarSubmicrometer diameter, light emitting fibers of poly(vinyl alcohol) (PVA) doped with pseudoisocyanine (1,1′-diethyl-2,2′-cyanine bromide, PIC) dye were prepared by electrospinning. A horizontal setup was employed with a stationary collector consisting of two parallel-positioned metal strips separated by a void gap. Formation of uniaxially aligned and randomly deposited fibers in electrospun films was confirmed by microscopy. Photoluminescence (PL) spectroscopy is used to evaluate spectral properties of both types of fibers doped with PIC. While PIC molecules were individually dispersed in PVA solution, they assemble into J-aggregates upon electrospinning when the weight fraction of PIC molecules is above 2.5 wt %. The formation of J-aggregates was observed in both randomly deposited and uniaxially aligned electrospun fibers. Moreover, the fibers aligned uniaxially showed a high degree of polarized emission (PL |/PL⊥)10), arising from the orientation of J-aggregates along the fiber axis. On the other hand, isotropic emission of J-aggregates was observed from the fibers deposited randomly. As a conclusion, electrospinning was found to be an efficient and a practical method to form highly oriented J-aggregates dispersed into polymer fibers. To the best of our knowledge, it is the first time formation of J-aggregates (a bottom-up approach) and electrospinning (a topdown approach) is successfully combined.