WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 4Citation - Scopus: 5Development of Ab3-Type Novel Phthalocyanine and Porphyrin Photosensitizers Conjugated With Triphenylphosphonium for Higher Photodynamic Efficacy(American Chemical Society, 2022) Albakour, Mohamad; Önal, Emel; Tüncel, Özge; Erdoğan, İpek; Gümüşgöz Çelik, Gizem; Küçük, Tuǧba; Akgül, Bünyamin; Gürek, Ayşe Gül; Özçelik, SerdarThere are a number of lipophilic cations that can be chosen; the triphenylphosphonium (TPP) ion is particularly unique for mitochondrion targeting, mainly due to its simplicity in structure and ease to be linked to the target molecules. In this work, mitochondrion-targeted AB3-type novel phthalocyanine and porphyrin photosensitizers (PSs) were synthesized and their photophysical photochemical properties were defined. Fluorescence quantum yields (φF) are 0.009, 0.14, 0.13, and 0.13, and the singlet-oxygen quantum yields (φΔ) are 0.27, 0.75, 0.57, and 0.58 for LuPcPox(OAc), AB3TPP-Pc, AB3TPP-Por-C4, and AB3TPP-Por-C6, respectively. To evaluate the photodynamic efficacy of the TPP-conjugated PS cell viabilities of A549 and BEAS-2B lung cells were comparatively measured and IC-50 values were determined. AB3TPP-Por-C4, AB3TPP-Por-C6, and AB3TPP-Pc compounds compared to the reference molecules ZnPc and H2TPP were found to be highly cytotoxic (sub-micromolar concentration) under the light. LuPcPox(OAc) is the most effective molecule regarding cell killing (the activity). The cell killing of the TPP-conjugated porphyrin derivatives exhibits a similar response compared to LuPcPox(OAc) when the light absorbing factor of the PS is normalized at 660 nm: TPP-conjugated porphyrins absorb less light (lower extinction coefficient) but produce more radical species (higher singlet-oxygen quantum yield) and therefore effectively kill the cells. The singlet oxygen-producing capacity of AB3TPP-Pc is almost 3 times higher compared to LuPcPox(OAc) and 50% more efficient with respect to ZnPc, suggesting that TPP-conjugated phthalocyanine may serve as a good photosensitizer for photodynamic therapy (PDT). The high singlet oxygen generation capacity of these novel TPP-conjugated porphyrin and phthalocyanine PS suggests that they might be useful for PDT requiring lower photosensitizer concentration and reduced energy deposited through less light exposure.Article Citation - WoS: 3Citation - Scopus: 5Physically Unclonable Security Patterns Created by Electrospinning, and Authenticated by Two-Step Validation Method(IOP Publishing, 2022) Taşcıoğlu, Didem; Atçı, Arda; Sevim Ünlütürk, Seçil; Özçelik, SerdarCounterfeiting is a growing economic and social problem. For anticounterfeiting, random and inimitable droplet/fiber patterns were created by the electrospinning method as security tags that are detectable under UV light but invisible in daylight. To check the authenticity of the original security patterns created; images were collected with a simple smartphone microscope and a database of the recorded original patterns was created. The originality of the random patterns was checked by comparing them with the patterns recorded in the database. In addition, the spectral signature of the patterns in the droplet/fiber network was obtained with a simple and hand-held spectrometer. Thus, by reading the spectral signature from the pattern, the spectral information of the photoluminescent nanoparticles was verified and thus a second-step verification was established. In this way, anticounterfeiting technology that combines ink formula, unclonable security pattern creation and two-level verification is developed.Article Citation - WoS: 2Citation - Scopus: 2Mn2+ Ions Incorporated Into Znsxse1-X Colloidal Quantum Dots: Controlling Size and Composition of Nanoalloys and Regulating Magnetic Dipolar Interactions(IOP Publishing, 2021) Ünlütürk, Seçil Sevim; Akdoğan, Yaşar; Özçelik, SerdarA facile synthesis method is introduced how to prepare magnetically active ultraviolet emitting manganese ions incorporated into ZnSxSe1-x colloidal quantum dot (nanoalloy) at 110 degrees C in aqueous solutions. The reaction time is the main factor to control the hydrodynamic size from 3 to 10 nm and the precursor ratio is significant to tune the alloy composition. ZnS shell layer on the ZnSxSe1-x core was grown to passivate environmental effects. The nanoalloy has ultraviolet emission at 380 nm having a lifetime of 80 ns and 7% quantum yield. The incorporation of Mn2+ ions into the nanoalloys induced magnetic activity but did not modify the structure and photophysical properties of the nanoalloys. Colloidal and powdery samples were prepared and analyzed by electron paramagnetic resonance (EPR) spectroscopy. In the colloidal dispersions, EPR spectra showed hyperfine line splitting regardless of the Mn2+ ion fractions, up to 6%, indicating that Mn2+ ions incorporated into the nanoalloys were isolated. EPR signals of the powdery samples were broadened when the fraction of Mn2+ ions was higher than 0.1%. The EPR spectra were simulated to reveal the locations and interactions of Mn2+ ions. The simulations suggest that the Mn2+ ions are located on the nanoalloy surfaces. These findings infer that the magnetic dipolar interactions are regulated by the initial mole ratio of Mn/Zn and the physical state of the nanoalloys adjusted by preparation methods.Article Citation - WoS: 22Citation - Scopus: 18Nuclear-Targeted Gold Nanoparticles Enhance Cancer Cell Radiosensitization(IOP Publishing, 2020) Pratx, Guillem; Özçelik, SerdarRadiation therapy aims to kill or inhibit proliferation of cancer cells while sparing normal cells. To enhance radiosensitization, we developed 40 nm-sized gold nanoparticles targeting the nucleus. We exploited a strategy that combined RGD and NLS peptides respectively targeting cancer cell and the nucleus to initiate cell-death activated by x-ray irradiation. We observed that the modified gold nanoparticles were either translocated in the nuclei or accumulated in the vicinity of the nuclei. We demonstrated that x-ray irradiation at 225 kVp energy reduced cell proliferation by 3.8-fold when the nuclear targeted gold nanoparticles were used. We determined that the radiation dose to have a 10% survival fraction was reduced from 11.0 Gy to 7.1 Gy when 10.0 mu g ml(-1)of the NLS/RGD/PEG-AuNP was incubated with A549 cancer cells. We conclude that the peptide-modified gold nanoparticles targeting the nucleus significantly enhance radiosensitization.Article Citation - WoS: 8Citation - Scopus: 7Engineered Silica Nanoparticles Are Biologically Safe Vehicles To Deliver Drugs or Genes To Liver Cells(Elsevier Ltd., 2021) Tüncel, Özge; Kahraman, Erkan; Bağcı, Gülsün; Atabey, Neşe; Özçelik, SerdarEngineered silica nanoparticles (SiNP) are emerging materials for medical applications. Evaluating biological responses of specific cells treated with engineered silica nanoparticles is however essential. We synthesized and characterized the physicochemical properties of silica nanoparticles with two different sizes of 10 and 100 nm (10SiNP and 100SiNP) dispersed in cell culture medium. HuH-7, an epithelial-like human hepatoblastoma cell line and SK-HEP-1, a liver sinusoidal endothelial cell line (LSEC) are employed to evaluate their biological responses for the SiNP treatment. Primary human lymphocytes are used to assess genotoxicity recommended by OECD guidelines while erythrocytes are used to assess hemolytic activity. The engineered silica nanoparticles are not able to produce radical species, to alter the mitochondrial membrane potential, and induce any adverse effects on cell proliferation. The colony formation ability of HuH-7 hepatoblastoma cells was not affected following the SiNP treatment. Furthermore, SiNPs do not induce hemolysis of red blood cells and are not genotoxic. These findings suggest that SiNPs regardless of the size, amount, and incubation time are biologically safe vehicles to deliver drugs or genes to the liver. © 2020 Elsevier B.V.Article Citation - WoS: 13Citation - Scopus: 13Single Chain Cationic Polymer Dot as a Fluorescent Probe for Cell Imaging and Selective Determination of Hepatocellular Carcinoma Cells(American Chemical Society, 2019) Özenler, Sezer; Yücel, Müge; Tüncel, Özge; Kaya, Hakan; Özçelik, Serdar; Yıldız, Ümit HakanThis letter describes formation of single chain cationic polymer dots (Pdots) made of poly[1,4-dimethy1-1-(34(2,4,5-trimethylthiophen-3-yl)oxy)propyl)piperazin-1-ium bromide] conjugated polyelectrolyte (CPE). The single chain Pdot formation relies on a simple process which is a rapid nanophase separation between CPE solution of ethylene glycol and water. Pdots show narrow monodisperse size distribution with a 3.6 nm in diameter exhibiting high brightness and excellent colloidal and optical stability. It has been demonstrated that photoluminescent Pdots provide selective nuclear translocation to hepatocellular carcinoma cells as compared to healthy liver cells. The Pdot labeling effectively discriminates cancer cells in the coculture media. Pdots hold great promise as a luminescent probe to diagnose cancer cells in histology and may guide surgeons during operations to precisely separate out cancerous tissue due to augmented fluorescence brightness.Article Citation - WoS: 50Citation - Scopus: 57Biofunctional Quantum Dots as Fluorescence Probe for Cell-Specific Targeting(Elsevier Ltd., 2014) Ağ, Didem; Bongartz, Rebecca; Eral Doğan, Leyla; Seleci, Muharrem; Walter, Johanna G.; Odacı Demirkol, Dilek; Stahl, Frank; Özçelik, Serdar; Timur, Suna; Scheper, ThomasWe describe here the synthesis, characterization, bioconjugation, and application of water-soluble thioglycolic acid TGA-capped CdTe/CdS quantum dots (TGA-QDs) for targeted cellular imaging. Anti-human epidermal growth factor receptor 2 (HER2) antibodies were conjugated to TGA-QDs to target HER2-overexpressing cancer cells. TGA-QDs and TGA-QDs/anti-HER2 bioconjugates were characterized by fluorescence and UV-Vis spectroscopy, X-ray diffraction (XRD), hydrodynamic sizing, electron microscopy, and gel electrophoresis. TGA-QDs and TGA-QDs/anti-HER2 were incubated with cells to examine cytotoxicity, targeting efficiency, and cellular localization. The cytotoxicity of particles was measured using an MTT assay and the no observable adverse effect concentration (NOAEC), 50% inhibitory concentration (IC50), and total lethal concentration (TLC) were calculated. To evaluate localization and targeting efficiency of TGA-QDs with or without antibodies, fluorescence microscopy and flow cytometry were performed. Our results indicate that antibody-conjugated TGA-QDs are well-suited for targeted cellular imaging studies.Article Citation - WoS: 33Citation - Scopus: 33Folic Acid Modified Clay/Polymer Nanocomposites for Selective Cell Adhesion(Royal Society of Chemistry, 2014) Barlas, Fırat Barış; Ağ Şeleci, Didem; Özkan, Melek; Demir, Bilal; Şeleci, Muharrem; Aydın, Muhammed; Taşdelen, M. A.; Zareie, Hadi M.; Timur, Suna; Özçelik, Serdar; Yağcı, YusufA folic acid (FA) modified poly(epsilon-caprolactone)/clay nanocomposite (PCL/MMT-(CH2CH2OH)2-FA) resulting in selective cell adhesion and proliferation was synthesized and characterized as a cell culture and biosensing platform. For this purpose, first the FA modified clay (MMT-(CH2CH2OH)2-FA) was prepared by treating the organo-modified clay, Cloisite 30B [MMT-(CH2CH 2OH)2] with FA in chloroform at 60°C. Subsequent ring opening polymerization of ε-caprolactone in the presence of tin octoate (Sn(Oct)2) using MMT-(CH2CH2OH)2-FA at 110°C resulted in the formation of MMT-(CH2CH 2OH)2-FA with an exfoliated clay structure. The structures of intermediates and the final nanocomposite were investigated in detail by FT-IR spectral analysis and DSC, TGA, XRD, SEM and AFM measurements. The combination of FA, PCL and clay provides a simple and versatile route to surfaces that allows controlled and selective cell adhesion and proliferation. FA receptor-positive HeLa and negative A549 cells were used to prove the selectivity of the modified surfaces. Both microscopy and electrochemical sensing techniques were applied to show the differences in cell adherence on the modified and pristine clay platforms. This approach is expected to be adapted into various bio-applications such as 'cell culture on chip', biosensors and design of tools for targeted diagnosis or therapy.Article Citation - WoS: 56Citation - Scopus: 57Dynamic Nuclear Polarization of Spherical Nanoparticles(Royal Society of Chemistry, 2013) Akbey, Ümit; Altın, Burcu; Linden, Arne; Özçelik, Serdar; Gradzielski, Michael; Oschkinat, HartmutSpherical silica nanoparticles of various particle sizes (∼10 to 100 nm), produced by a modified Stoeber method employing amino acids as catalysts, are investigated using Dynamic Nuclear Polarization (DNP) enhanced Nuclear Magnetic Resonance (NMR) spectroscopy. This study includes ultra-sensitive detection of surface-bound amino acids and their supramolecular organization in trace amounts, exploiting the increase in NMR sensitivity of up to three orders of magnitude via DNP. Moreover, the nature of the silicon nuclei on the surface and the bulk silicon nuclei in the core (sub-surface) is characterized at atomic resolution. Thereby, we obtain unique insights into the surface chemistry of these nanoparticles, which might result in improving their rational design as required for promising applications, e.g. as catalysts or imaging contrast agents. The non-covalent binding of amino acids to surfaces was determined which shows that the amino acids not just function as catalysts but become incorporated into the nanoparticles during the formation process. As a result only three distinct Q-types of silica signals were observed from surface and core regions. We observed dramatic changes of DNP enhancements as a function of particle size, and very small particles (which suit in vivo applications better) were hyperpolarized with the best efficiency. Nearly one order of magnitude larger DNP enhancement was observed for nanoparticles with 13 nm size compared to particles with 100 nm size. We determined an approximate DNP penetration-depth (∼4.2 or ∼5.7 nm) for the polarization transfer from electrons to the nuclei of the spherical nanoparticles. Faster DNP polarization buildup was observed for larger nanoparticles. Efficient hyperpolarization of such nanoparticles, as achieved in this work, can be utilized in applications such as magnetic resonance imaging (MRI).Article Citation - WoS: 9Citation - Scopus: 9Tuning Photoinduced Intramolecular Electron Transfer by Electron Accepting and Donating Substituents in Oxazolones(Springer, 2013) Öztürk, Gülsiye; Karabıyık, Hasan; Aygün, Muhittin; Alp, Serap; Özçelik, SerdarThe solvatochromic and spectral properties of oxazolone derivatives in various solvents were reported. Fluorescence spectra clearly showed positive and negative solvatochromism depending on substituents. The solvatochromic plots and quantum chemical computations at DFT-B3LYP/6-31+G(d,p) level were used to assess dipole moment changes between the ground and the first excited singlet-states. The electron accepting nitro substituent at the para-position increased the π-electron mobility, however, the 3,5-dinitro substituent decreased the π-electron mobility as a result of inverse accumulation of the electronic density as compared with that of its ground state. Experimental and computational studies proved that the photoinduced intramo- lecular electron transfer (PIET) is responsible for the observed solvatochromic effects. We demonstrate that PIET can be finely tailored by the position of the electron accepting and donating substituents in the phenyl ring of the oxazolone de- rivatives.We propose that the photoactive CPO derivatives are new molecular class of conjugated push-pull structures using azlactone moiety as the π-conjugated linker and may find applications in photovoltaic cells and light emitting diodes.