Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Citation - WoS: 51Citation - Scopus: 53Bodipy-Au(i): a Photosensitizer for Singlet Oxygen Generation and Photodynamic Therapy(American Chemical Society, 2017) Üçüncü, Muhammed; Karakuş, Erman; Kurulgan Demirci, Eylem; Sayar, Melike; Dartar, Suay; Emrullahoğlu, MustafaUpon complexation with Au(I), a photoinactive BODIPY derivative was transformed into a highly photoactive triplet sensitizer. Along with high efficiency in singlet oxygen generation (φδ = 0.84), the new BODIPY-Au(I) skeleton showed excellent photocytotoxic activity against cancer cell lines (EC50 = 2.5 nM).Article Citation - WoS: 80Citation - Scopus: 82Electrophilic Cyanate as a Recognition Motif for Reactive Sulfur Species: Selective Fluorescence Detection of H2s(American Chemical Society, 2016) Karakuş, Erman; Üçüncü, Muhammed; Emrullahoğlu, MustafaAn ESIPT-based fluorescent dye, 3-hydroxyflavone, is chemically masked with an electrophilic cyanate motif in order to construct a fluorescent probe for cellular sulfur species. This novel probe structure, displays an extremely fast, highly sensitive and selective "turn-on" type fluorescent response toward H2S. We have also documented its utility for imaging of H2S in the living cells.Article Citation - WoS: 22Citation - Scopus: 24A Fluorescein-Based Chemodosimeter for Selective Gold(iii) Ion Monitoring in Aqueous Media and Living Systems(Elsevier Ltd., 2016) Çetintaş, Ceyla; Karakuş, Erman; Üçüncü, Muhammed; Emrullahoğlu, MustafaWe constructed a turn-on type chemodosimeter based upon a fluorescein scaffold for the rapid, selective detection of gold(III) ions over other metal species. This novel probe structure offers distinct features including high water solubility, a low detection limit, rapid response time and applicability in imaging gold(III) ions in living cells.Article Citation - WoS: 15Citation - Scopus: 15Bodipy-Conjugated Chitosan Nanoparticles as a Fluorescent Probe(Taylor and Francis Ltd., 2017) Bor, Gizem; Üçüncü, Muhammed; Emrullahoğlu, Mustafa; Tomak, Aysel; Şanlı Mohamed, GülşahRecently, development of fluorescent nanoparticle-based probes for various bioimaging applications has attracted great attention. This work aims to develop a new type fluorescent nanoparticle conjugate and evaluate its cytotoxic effects on A549 and BEAS 2B cell lines. Throughout the study, ionically crosslinked chitosan nanoparticles (CNs) were conjugated with carboxylated 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY-COOH). The results of conjugates (BODIPY-CNs) were investigated with regard to their physic-chemical, optical, cytotoxic properties and cellular internalization. The morphology of BODIPY-CNs was found to be spherical in shape and quite uniform having average diameter of 70.25 ± 11.99 nm. Cytotoxicty studies indicated that although BODIPY-COOH itself was quite toxic on both A549- and BEAS 2B-treated cells, CNs increased the cell viability of both cell lines via conjugation to BODIPY-COOH fluorescent molecule up to 67% for A549 and 74% for BEAS 2B cells. These results may suggest a possible utilization of the new fluorescent nanoparticle-based probe for bioimaging in biology and medicine.Article Citation - WoS: 36Citation - Scopus: 37A Bodipy-Based Fluorescent Probe for Ratiometric Detection of Gold Ions: Utilization Of: Z -Enynol as the Reactive Unit(Royal Society of Chemistry, 2016) Üçüncü, Muhammed; Karakuş, Erman; Emrullahoğlu, MustafaUsing an irreversible intramolecular cyclisation pathway triggered by gold ions, a boron-dipyrromethene (BODIPY) based fluorescent probe integrated with a reactive Z-enynol motif responds selectively to gold ions. With the addition of gold(iii), the probe displays ratiometric fluorescence behaviour clearly observable to the naked eye under both visible and UV light. © The Royal Society of Chemistry 2016.Article Citation - WoS: 33Citation - Scopus: 36Epr Studies of Intermolecular Interactions and Competitive Binding of Drugs in a Drug-Bsa Binding Model(Royal Society of Chemistry, 2016) Akdoğan, Yaşar; Emrullahoğlu, Mustafa; Tatlıdil, Diğdem; Üçüncü, Muhammed; Çakan Akdoğan, GülçinUnderstanding intermolecular interactions between drugs and proteins is very important in drug delivery studies. Here, we studied different binding interactions between salicylic acid and bovine serum albumin (BSA) using electron paramagnetic resonance (EPR) spectroscopy. Salicylic acid was labeled with a stable radical (spin label) in order to monitor its mobilized (free) or immobilized (bound to BSA) states. In addition to spin labeled salicylic acid (SL-salicylic acid), its derivatives including SL-benzoic acid, SL-phenol, SL-benzene, SL-cyclohexane and SL-hexane were synthesized to reveal the effects of various drug binding interactions. EPR results of these SL-molecules showed that hydrophobic interaction is the main driving force. Whereas each of the two functional groups (-COOH and -OH) on the benzene ring has a minute but detectable effect on the drug-protein complex formation. In order to investigate the effect of electrostatic interaction on drug binding, cationic BSA (cBSA) was synthesized, altering the negative net charge of BSA to positive. The salicylic acid loading capacity of cBSA is significantly higher compared to that of BSA, indicating the importance of electrostatic interaction in drug binding. Moreover, the competitive binding properties of salicylic acid, ibuprofen and aspirin to BSA were studied. The combined EPR results of SL-salicylic acid/ibuprofen and SL-ibuprofen/salicylic acid showed that ibuprofen is able to replace up to ∼83% of bound SL-salicylic acid, and salicylic acid can replace only ∼14% of the bound SL-ibuprofen. This indicates that ∼97% of all salicylic acid and ibuprofen binding sites are shared. On the other hand, aspirin replaces only ∼23% of bound SL-salicylic acid, and salicylic acid replaces ∼50% of bound SL-aspirin, indicating that ∼73% of all salicylic acid and aspirin binding sites are shared. These results show that EPR spectroscopy in combination with the spin labeling technique is a very powerful method to investigate drug binding dynamics in detail.Article Citation - WoS: 24Citation - Scopus: 27Physiological Concentrations of Albumin Favor Drug Binding(Royal Society of Chemistry, 2015) Tatlıdil, Diğdem; Üçüncü, Muhammed; Akdoğan, YaşarThe ability to track drug binding and release makes electron paramagnetic resonance (EPR) spectroscopy well suited for drug delivery studies. Using the continuous wave (cw) EPR technique to extract information about the dynamics of the spin labeled drugs we can simultaneously determine the bound and unbound drugs. Here, spin labeled salicylic acid (SLSA) binding to and release from bovine serum albumin (BSA) is investigated, as a model for drug-transport protein interaction. We studied SLSA-BSA binding in a wide concentration range and found that the stoichiometry of the drug-protein increases significantly when the physiological range of BSA concentration is reached. Our EPR results explicitly reveal that up to ∼7 SLSA can bind to one albumin at the physiological concentration, whereas at lower BSA concentrations (<0.125 mM) the SLSA-BSA stoichiometry is maximum 2. Moreover, we studied drug release and showed that the ratio of bound to unbound SLSA concentrations remains relatively stable during dialysis. This indicates that the binding equilibrium of SLSA is not altered through the process of dialysis. This study demonstrates that cw EPR spectroscopy in combination with spin labeled drugs is an effective technique for binding and release studies and stoichiometric analysis of drug-protein interactions.Article Citation - WoS: 24Citation - Scopus: 24A Ratiometric Fluorescent Probe for Gold and Mercury Ions(John Wiley and Sons Inc., 2015) Üçüncü, Muhammed; Karakuş, Erman; Emrullahoğlu, MustafaA fluorescent probe that displays a ratiometric fluorescence response towards gold and mercury ions has been devised. Emitting at a relatively longer wavelength, the conjugated form of the fluorescent dye transforms in the presence of the gold or mercury ions into a new dye, the molecular structure of which lacks the conjugation and consequently emits at a distinctly shorter wavelength. A fluorescent probe that displays a ratiometric fluorescence response towards gold and mercury ions has been devised. Emitting at a relatively longer wavelength, the conjugated form of the fluorescent dye transforms in the presence of the gold or mercury ions into a new dye (see figure).Article Citation - WoS: 5Citation - Scopus: 5A Rare ?-Pyranopyrazole Skeleton: Design, One-Pot Synthesis and Computational Study(Royal Society of Chemistry, 2016) Üçüncü, Muhammed; Cantürk, Ceren; Karakuş, Erman; Zeybek, Hüseyin; Bozkaya, Uğur; Soydaş, Emine; Şahin, Ertan; Emrullahoğlu, MustafaDrawing upon a consecutive amide coupling and intramolecular cyclisation pathway, a one-pot, straightforward synthetic route has been developed for a range of pyrazole fused γ-pyrone derivatives. The reaction mechanism proposed for the chemoselective formation of γ-pyranopyrazole is furthermore fully supported by experimental and computational studies. © The Royal Society of Chemistry 2016.Article Citation - WoS: 22Citation - Scopus: 25A Bodipy/Pyridine Conjugate for Reversible Fluorescence Detection of Gold(iii) Ions(Royal Society of Chemistry, 2015) Üçüncü, Muhammed; Karakuş, Erman; Emrullahoğlu, MustafaWe designed a "turn-on" type fluorescent probe based on a BODIPY-pyridine conjugate which exhibits high selectivity towards Au(iii) ions and, also responds to changes in the pH within the acidic pH range. The probe offers features such as a rapid response time, a low detection limit, and high sensitivity and selectivity. The detection of Au(iii) is recognized by a distinct change in the emission intensity which relies on a reversible "ligand to ion" binding mechanism. We also document the utility of the probe for the quantification of gold ion residues in synthetic end products prepared via gold catalysis. © 2015 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.