Yazar "Yavuz, Mustafa S." seçeneğine göre listele

Listeleniyor 1 - 6 / 6
  • Küçük Resim Yok
    Öğe
    Exceptional organic solvent uptake by disulfide-linked polymeric networks
    (ROYAL SOC CHEMISTRY, 2014) Patel, Hasmukh A.; Yavuz, Mustafa S.; Yavuz, Cafer T.
    Disulfide-linked covalent organic polymers (COPs) were prepared through catalyst-free oxidative coupling polymerization. Owing to the excellent swelling behavior, low cost, and efficient synthesis, these materials can be promising materials for removal of organics in concentrated streams. COPs show 1,4-dioxane uptake up to 1.8 g g(-1).
  • Küçük Resim Yok
    Öğe
    Laser-Triggered Degelation Control of Gold Nanoparticle Embedded Peptide Organogels
    (AMER CHEMICAL SOC, 2013) Erdogan, Hakan; Sakalak, Huseyin; Yavuz, Mustafa S.; Demirel, Gokhan
    Further understanding of the interactions between nanoparticles (NPs) and biological molecules offers new possibilities in the applications of nanomedicine and nanodiagnostics. The properties of NPs, including size, shape, and surface functionality, play a decisive role in these interactions. Herein, we evaluated the influences of gold NPs (AuNPs) with different sizes (5-60 nm) and shapes (i.e., spherical, rod, and cage) on the self assembly of diphenylalanine (Phe-Phe) dipeptides. We found that the size of AuNPs smaller than 10 nm did not affect the self-assembly process of Phe-Phe, while bigger AuNPs (>10 nm) caused the formation of starlike peptide morphologies connected to one center. In the case of shape differences, nanorod and nanocage morphologies acted differently than spherical ones and caused the formation of densely packed, networklike dipeptide morphologies. In addition to these experiments, by combining photothermal properties of AuNPs with a Phe-Phe-based organogel having a thermo-responsive property, we demonstrated that the degelation process of AuNPs embedded organogels may be controlled by laser illumination. Complete degelation was achieved in about 10 min. We believe that such control may open the door to new opportunities for a number of applications, such as controlled release of drugs and tissue engineering.
  • Küçük Resim Yok
    Öğe
    Measuring Temperature Change at the Nanometer Scale on Gold Nanoparticles by Using Thermoresponsive PEGMA Polymers
    (WILEY-V C H VERLAG GMBH, 2017) Yavuz, Mustafa S.; Citir, Murat; Cavusoglu, Halit; Demirel, Gokhan
    Plasmonic heating of gold nanoparticles (AuNPs) under laser illumination is a highly desirable technique, especially for cancer therapy. However, significant drawbacks still remain including uncontrolled heat release from AuNPs, random exposure duration, and selection of the proper laser power without damaging normal healthy cells. Herein, we demonstrate a simple and versatile method to measure temperature variation on the surface of Au nanoparticles under laser irradiation based on a thermoresponsive polymer, poly(ethylene glycol) methylether methacrylate (PEGMA). In this context, a series of PEGMA polymers were synthesized to have different lower critical solution temperature (LCST) values (28-90 degrees C) and conjugated to the surface of spherical AuNPs by a gold-thiolate linkage. According to our strategy, the AuNPs first photothermally absorb light energy and convert it to heat owing to their tailored photothermal characteristics. The generated heat from the AuNPs subsequently dissipates into the surrounding thermoresponsive PEGMA polymer. When the temperature generated on the Au surface upon laser irradiation for a certain exposure time reaches the LCST value of the surrounding PEGMA polymer, the polymer chain collapses. Therefore, the hydrodynamic diameter of the PEGMA-coated AuNPs changes, which can be easily monitored by using dynamic light scattering (DLS). We systematically measured the temperature (28-90 degrees C) generated on the AuNP surfaces by using different laser power densities with varying durations. We believe that the resulting strategy will be very valuable for oncologists to easily predict the minimum laser power and duration needed to destroy the cancer cells through the photothermal effect of Au nanostructures.
  • Küçük Resim Yok
    Öğe
    One-pot synthesis of gold nanoparticles using tetradentate porphyrins
    (SPRINGER, 2011) Canitez, Fatma K.; Yavuz, Mustafa S.; Ozturk, Ramazan
    In this study, the meso-tetra (p-hydroxyphenyl) porphyrin and meso-tetra (m-hydroxyphenyl) porphyrin were coated on to gold nanoparticles (AuNPs) via thioacetate anchors which easily dissociate to form S-Au bonds. 4-tert-butyl phenyl thioacetate-AuNPs were prepared and used as a monodentate passivant to control the size of the tetradentate porphyrin-AuNPs. The porphyrin-coated AuNPs were characterized by UV-Vis, TEM, XRD, and XPS analyses. The tetradentate porphyrin-AuNPs size is within a range of 5-15 nm in diameter with exotic shapes. The plausible network formation for AuNP@p-TPP-SAc and the capping structure of the AuNP@m-TPP-SAc have been suggested.
  • Küçük Resim
    Öğe
    Surface grafting of electrochemically crosslinked poly(3,4-ethylenedioxythiophene) (PEDOT) brushes via surface-initiated ring-opening metathesis polymerization
    (PERGAMON-ELSEVIER SCIENCE LTD, 2012) Yavuz, Mustafa S.; Sotzing, Gregory A.
    Herein we demonstrated the preparation of 3,4-ethylenedioxythiophene (EDOT) containing polynorbornylene brushes on Au surfaces via surface-initiated ring-opening metathesis polymerization (SI-ROMP). Using solid-state oxidative crosslinking technique, these polymer brushes were electrochemically converted to conjugated polymer networks. Grazing-angle FTIR spectra of polymer brushes clearly showed the characteristic vibrations of EDOT and norbornylene groups. Furthermore, densely covered Au substrates with polynorbornylene brushes were characterized by using scanning electron microscopy and atomic force microscopy. (C) 2012 Elsevier Ltd. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Synthesis, conductivity and magnetic properties of poly(N-pyrrole phosphonic acid)-Fe3O4 nanocomposite
    (ELSEVIER SCIENCE SA, 2011) Temizel, Emine; Ayan, Esra; Senel, Mehmet; Erdemi, Hamit; Yavuz, Mustafa S.; Kavas, Huseyin; Baykal, Abdulhadi
    The present study describes the preparation and characterization of poly(N-pyrrole phosphonic acid)-Fe3O4 (PPP/Fe3O4-NPs) nanocomposite. Structural characterizations and some physical properties such as magnetism, ac-dc conductivity performance and dielectric permittivity of the nanocomposite were performed by FT-IR. XRD, TGA, TEM and VSM (vibrating sample magnetometer). FT-IR measurements of the nanocomposite showed that the Fe3O4-NPs bound to the polymer chains via phosphonic acid moieties. From the XRD powder pattern, the crystallite size was estimated as 11 +/- 4 nm which is consistent with the TEM micrographs and magnetic core size from VSM measurements. Analysis of conductivity and permittivity meausurements revealed the magnetic transition above 60 which gives rise to the maximum conductivity of 1.7 x 10(-6) S cm(-1) at 100 degrees C. (C) 2011 Elsevier B.V. All rights reserved.