WoS İndeksli Yayınlar Koleksiyonu

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  • Article
    Citation - WoS: 8
    Citation - Scopus: 8
    Thermo-Responsive Complexes of c-Myc Antisense Oligonucleotide With Block Copolymer of Poly(OEGMA) and Quaternized Poly(4-Vinylpyridine)
    (Wiley-VCH Verlag GmbH, 2016-11-03) Topuzogullari, Murat; Elalmis, Yeliz Basaran; Isoglu, Sevil Dincer
    Solution behavior of thermo-responsive polymers and their complexes with biological macromolecules may be affected by environmental conditions, such as the concentration of macromolecular components, pH, ion concentration, etc. Therefore, a thermo-responsive polymer and its complexes should be characterized in detail to observe their responses against possible environments under physiological conditions before biological applications. To briefly indicate this important issue, thermo-responsive block copolymer of quaternized poly(4-vinylpyridine) and poly(oligoethyleneglycol methyl ether methacrylate) as a potential nonviral vector has been synthesized. Polyelectrolyte complexes of this copolymer with the antisense oligonucleotide of c-Myc oncogene are also thermo-responsive but, have lower LCST (lower critical solution temperature) values compared to individual copolymer. LCST values of complexes decrease with molar ratio of macromolecular components and presence of salt. Dilution of solutions also affects solution behavior of complexes and causes a significant decrease in size and an increase in LCST, which indicates possible effects of severe dilutions in the blood stream.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Superior CdSe/ZnS@Fe2O3 Yolk-Shell Nanoparticles as Optically Active MRI Contrast Agents
    (Wiley-VCH Verlag GmbH, 2022-07) Ekici, Derya D.; Mutlugun, Evren
    We have developed a robust synthesis methodology for quantum dots (QDs) nanoparticles with magnetic properties designed for biomodal imaging. These nanocrsytlas consists of a semiconductor quantum dot core with engineered fluorescence, which is located in a paramagnetic iron oxide shell that acts as a magnetic resonance imaging (MRI) contrast agent. Yolk-shell CdSe/ZnS@Fe2O3 nanoparticles (NPs) are synthesized via sonochemical decomposition of iron pentacarbonyl (Fe(CO)(5)) using the oleylamine (OAm) as the ligand. The sonochemical synthesis method of magnetic fluorescent NPs that can be used as MRI contrast agents provided advantages such as improved quantum efficiency and homogeneous size distributions. It has been determined that the luminescence efficiency of quantum dots decreases in coatings that can be made at high temperatures by thermal decomposition. In order to eliminate the disadvantage of elevated temperatures, the sonochemical decomposition method, which allows coating at low temperatures, has been used. With this method, yolk-shell (CdSe/ZnS@Fe2O3) nanoparticles were produced with high photoluminescence quantum efficiency and homogeneous size distributions. The synthesis magnetic fluorescent NPs optimized was determined to have the injection temperature of Fe(CO)(5) at 60 degrees C, Fe(CO)(5)/CdSe@ZnS ratio 0.7, OAm/Fe(CO)(5) volume ratio 1.43 with an oxidation time 5 min. Under these conditions, the quantum efficiency was found to be 78 %, nanoparticle sizes between 11-14 nm and r(1) value was 0.199, r(2) value was 0.518 in MRI analysis. These optically active magnetic fluorescent nanoparticles as positive contrast agents (T1 weighted) are predicted to pave the way for the future of advanced bio-imaging systems.
  • Article
    Citation - WoS: 11
    Citation - Scopus: 9
    Single-Mode Lasing From a Single 7 nm Thick Monolayer of Colloidal Quantum Wells in a Monolithic Microcavity
    (Wiley-VCH Verlag GmbH, 2021-03-03) Foroutan-Barenji, Sina; Erdem, Onur; Delikanli, Savas; Yagci, Huseyin Bilge; Gheshlaghi, Negar; Altintas, Yemliha; Demir, Hilmi Volkan
    In this work, the first account of monolithically-fabricated vertical cavity surface emitting lasers (VCSELs) of densely-packed, orientation-controlled, atomically flat colloidal quantum wells (CQWs) using a self-assembly method and demonstrate single-mode lasing from a record thin colloidal gain medium with a film thickness of 7 nm under femtosecond optical excitation is reported. Specially engineered CQWs are used to demonstrate these hybrid CQW-VCSELs consisting of only a few layers to a single monolayer of CQWs and are achieved the lasing from these thin gain media by thoroughly modeling and implementing a vertical cavity consisting of distributed Bragg reflectors with an additional dielectric layer for mode tuning. Accurate spectral and spatial alignment of the cavity mode with the CQW films is secured with the help of full electromagnetic computations. While overcoming the long-pending problem of limited electrical conductivity in thicker colloidal films, such ultrathin colloidal gain media can be helpful to enable fully electrically-driven colloidal lasers.
  • Article
    Citation - WoS: 36
    Citation - Scopus: 36
    Selective Remanent Ambipolar Charge Transport in Polymeric Field-Effect Transistors for High-Performance Logic Circuits Fabricated in Ambient
    (Wiley-VCH Verlag GmbH, 2014-10-06) Fabiano, Simone; Usta, Hakan; Forchheimer, Robert; Crispin, Xavier; Facchetti, Antonio; Berggren, Magnus
  • Article
    Citation - WoS: 128
    Citation - Scopus: 136
    Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth
    (Wiley-VCH Verlag GmbH, 2019-12-23) Liu, Baiquan; Altintas, Yemliha; Wang, Lin; Shendre, Sushant; Sharma, Manoj; Sun, Handong; Demir, Hilmi Volkan
    Colloidal quantum wells (CQWs) are regarded as a highly promising class of optoelectronic materials, thanks to their unique excitonic characteristics of high extinction coefficients and ultranarrow emission bandwidths. Although the exploration of CQWs in light-emitting diodes (LEDs) is impressive, the performance of CQW-LEDs lags far behind other types of soft-material LEDs (e.g., organic LEDs, colloidal-quantum-dot LEDs, and perovskite LEDs). Herein, high-efficiency CQW-LEDs reaching close to the theoretical limit are reported. A key factor for this high performance is the exploitation of hot-injection shell (HIS) growth of CQWs, which enables a near-unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films, and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape-, composition-, and device-engineering, the CQW-LEDs using CdSe/Cd0.25Zn0.75S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23 490 cd m(-2), extremely saturated red color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.715, 0.283), and stable emission are obtained. The findings indicate that HIS-grown CQWs enable high-performance solution-processed LEDs, which may pave the path for future CQW-based display and lighting technologies.
  • Article
    Citation - WoS: 15
    Citation - Scopus: 16
    Quartz-Crystal Microbalance Measurements of Cd19 Antibody Immobilization on Gold Surface and Capturing B Lymphoblast Cells: Effect of Surface Functionalization
    (Wiley-VCH Verlag GmbH, 2018-02-05) Icoz, Kutay; Soylu, Mehmet Cagri; Canikara, Zeynep; Unal, Ekrem
    We have investigated different surface functionalization methods to immobilize CD19 antibody on gold surface to capture B lymphoblast cells associated with the acute lymphoblastic leukemia disease. Quartz Crystal Microbalance measurements were performed to analyze the binding kinetics of each layer and determine the optimum method, which results in higher cell capture rates. The random orientation of antibody and oriented antibody through protein G was investigated and protein G presence resulted in 15,2Hz frequency shift for 10(4)cells/mL. The 3-mercaptopropyltrimethoxysilane (MPS) and 11-Mercaptoundecanoic acid (MUA) coatings of gold surface together with 4-(N-Maleimidomethyl)cyclohexane-1-carboxylic acid 3-sulfo-N-hydroxysuccinimide ester sodium salt (Sulfo-SMCC) and N-Ethyl-N'-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)/N-hydroxysulfosuccinimide (NHS) linker layers were tested on QCM for protein G and antibody binding. The results indicate that MUA, EDC/NHS, protein G, antibody CD19 is the optimum surface modification among the tested combinations. By using the optimum surface functionalization method, minimum 10(3) cell per mL was measured as 1.9Hz frequency shift.
  • Article
    Citation - WoS: 88
    Citation - Scopus: 83
    Organic Light-Emitting Physically Unclonable Functions
    (Wiley-VCH Verlag GmbH, 2021-12-22) Kayaci, Nilgun; Ozdemir, Resul; Kalay, Mustafa; Kiremitler, N. Burak; Usta, Hakan; Onses, M. Serdar
    The development of novel physically unclonable functions (PUFs) is of growing interest and fluorescent organic semiconductors (f-OSCs) offer unique advantages of structural versatility, solution-processability, ease of processing, and great tuning ability of their physicochemical/optoelectronic/spectroscopic properties. The design and ambient atmosphere facile fabrication of a unique organic light-emitting physically unclonable function (OLE-PUF) based on a green-emissive fluorescent oligo(p-phenyleneethynylene) molecule is reported. The OLE-PUFs have been prepared by one-step, brief (5 min) thermal annealing of spin-coated nanoscopic films (approximate to 40 nm) at a modest temperature (170 degrees C), which results in efficient surface dewetting to form randomly positioned/sized hemispherical features with bright fluorescence. The random positioning of molecular domains generated the unclonable surface with excellent uniformity (0.50), uniqueness (0.49), and randomness (p > 0.01); whereas the distinctive photophysical and structural properties of the molecule created the additional security layers (fluorescence profile, excited-state decay dynamics, Raman mapping/spectrum, and infrared spectrum) for multiplex encoding. The OLE-PUFs on substrates of varying chemical structures, surface energies and flexibility, and direct deposition on goods via drop-casting are demonstrated. The OLE-PUFs immersed in water, exposed to mechanical abrasion, and read-out repeatedly via fluorescence imaging showed great stability. These findings clearly demonstrate that rationally engineered solution-processable f-OSCs have a great potential to become a key player in the development of new-generation PUFs.
  • Article
    Citation - WoS: 11
    Citation - Scopus: 12
    Optical Gain in Ultrathin Self-Assembled Bi-Layers of Colloidal Quantum Wells Enabled by the Mode Confinement in Their High-Index Dielectric Waveguides
    (Wiley-VCH Verlag GmbH, 2020-10-20) Foroutan-Barenji, Sina; Erdem, Onur; Gheshlaghi, Negar; Altintas, Yemliha; Demir, Hilmi Volkan
    This study demonstrates an ultra-thin colloidal gain medium consisting of bi-layers of colloidal quantum wells (CQWs) with a total film thickness of 14 nm integrated with high-index dielectrics. To achieve optical gain from such an ultra-thin nanocrystal film, hybrid waveguide structures partly composed of self-assembled layers of CQWs and partly high-index dielectric material are developed and shown: in asymmetric waveguide architecture employing one thin film of dielectric underneath CQWs and in the case of quasi-symmetric waveguide with a pair of dielectric films sandwiching CQWs. Numerical modeling indicates that the modal confinement factor of ultra-thin CQW films is enhanced in the presence of the adjacent dielectric layers significantly. The active slabs of these CQW monolayers in the proposed waveguide structure are constructed with great care to obtain near-unity surface coverage, which increases the density of active particles, and to reduce the surface roughness to sub-nm scale, which decreases the scattering losses. The excitation and propagation of amplified spontaneous emission (ASE) along these active waveguides are experimentally demonstrated and numerically analyzed. The findings of this work offer possibilities for the realization of ultra-thin electrically driven colloidal laser devices, providing critical advantages including single-mode lasing and high electrical conduction.
  • Article
    Citation - WoS: 13
    Citation - Scopus: 14
    Near-Field Energy Transfer Into Silicon Inversely Proportional to Distance Using Quasi-2D Colloidal Quantum Well Donors
    (Wiley-VCH Verlag GmbH, 2021-09-12) Humayun, Muhammad Hamza; Hernandez-Martinez, Pedro Ludwig; Gheshlaghi, Negar; Erdem, Onur; Altintas, Yemliha; Shabani, Farzan; Demir, Hilmi Volkan
    Silicon is the most prevalent material system for light-harvesting applications; however, its inherent indirect bandgap and consequent weak absorption limits its potential in optoelectronics. This paper proposes to address this limitation by combining the sensitization of silicon with extraordinarily large absorption cross sections of quasi-2D colloidal quantum well nanoplatelets (NPLs) and to demonstrate excitation transfer from these NPLs to bulk silicon. Here, the distance dependency, d, of the resulting Forster resonant energy transfer from the NPL monolayer into a silicon substrate is systematically studied by tuning the thickness of a spacer layer (of Al2O3) in between them (varied from 1 to 50 nm in thickness). A slowly varying distance dependence of d(-1) with 25% efficiency at a donor-acceptor distance of 20 nm is observed. These results are corroborated with full electromagnetic solutions, which show that the inverse distance relationship emanates from the delocalized electric field intensity across both the NPL layer and the silicon because of the excitation of strong in-plane dipoles in the NPL monolayer. These findings pave the way for using colloidal NPLs as strong light-harvesting donors in combination with crystalline silicon as an acceptor medium for application in photovoltaic devices and other optoelectronic platforms.
  • Article
    Citation - WoS: 15
    Citation - Scopus: 16
    Natural Molecule-Incorporated Magnetic Organic-Inorganic Nanoflower: Investigation of Its Dual Fenton Reaction-Dependent Enzyme-Like Catalytic Activities With Cyclic Use
    (Wiley-VCH Verlag GmbH, 2023-04-03) Dadi, Seyma; Cardoso, Marlon Henrique; Mandal, Amit Kumar; Franco, Octavio Luiz; Ildiz, Nilay; Ocsoy, Ismail
    The functional organic-inorganic hybrid nanoflowers (hNFs) have recently attracted considerable attention due to enhanced catalytic activity and stability. The main purpose of this study is to synthesize new Fenton reagents and investigate their catalytic activity, dye degradation performance and antimicrobial activity. This magnetic gallic acid nanoflowers (FeGANF) were self-assembled via incorporating magnetic nanoparticles (Fe3O4 NPs) into gallic acid (GA) as organic part and copper(II) phosphate (Cu-3(PO4)(2)) as inorganic parts. The FeGANF were characterized by SEM, EDX, FT-IR and XRD. The peroxidase-like activity and dye degradation performance of FeGANF and GANF based on Fenton reaction in the presence of H2O2 was studied toward guaiacol as substrate, using methylene blue (MB) and congo red (CR) as a cationic and anionic dyes, respectively. FeGANF shows much high catalytic activity and decoloration efficiency (97 % for MB and 99 % for CR) because of dual active center in Fenton reaction on the surface of FeGANF. FeGANF exhibited more antimicrobial activity against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, and Candida albicans ATCC 10231 than that of the GA and GANF. The results of these studies suggest that magnetic hNFs has proved to be promising Fenton reagents for biological and environmental applications including treatment of wastewater.