Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Citation - WoS: 2Citation - Scopus: 2Transition-Metal Direct C-H Arylation of Thiophene in Aqueous Media Via Potassium Peroxymonosulfate(John Wiley and Sons Inc., 2019) Özenler, Sezer; Özenler, Sezer; Kaya, Hakan; Yıldız, Ümit Hakan; Elmacı, Nuran; Elmacı Irmak, Nuran; Yıldız, Ümit Hakan; 04.01. Department of Chemistry; 01. Izmir Institute of Technology; 04. Faculty of ScienceThis study covers the use of potassium peroxymonosulfate (PPS) which, is a mild and inexpensive catalyst, for direct coupling of C-H/C-H for water soluble thiophene. The 3-(4-methyl-3 '- thienyloxy)propyltriethylammonium bromide (M1) has been selected as model monomer that reacted PPS in 2.0, 0.20 and 0.020 monomer to PPS ratio. The reaction has been monitored via NMR spectroscopy revealing the monomer consumption and formation of dimers to tetramers as well as completion of reaction within 15 minutes. Resultant product is easily collected without tedious work up steps. The computational calculation has optimized the regularity of the coupling as head to tail, tail to tail, head to tail (HT-TT-HT) for tetramer. The regularity of tetramer which is further satisfied via NMR analysis showing emergence of new peaks at 3.56 and 4.48. The shifts in the UV maximum of reactive species have been monitored by absorbance spectroscopy showing time dependent red shift corresponds to growing from monomer to tetramers. The reaction has self-stopped due to low solubility of moderate condensates (higher than trimer), however further experiments have performed in water-organic mixtures showed great promises to obtain higher condensates.Article Citation - WoS: 39Citation - Scopus: 37Flow-Through Colorimetric Assay for Detection of Nucleic Acids in Plasma(Elsevier, 2019) Ammanath, Gopal; Yıldız, Ümit Hakan; Yeasmi, Sanjida; Srinivasulu, Yuvasri; Vats, Mukti; Cheema, Jamal Ahmed; Nabilah, Fairuz; Liedberg, Bo; Yıldız, Ümit Hakan; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyA flow-through colorimetric assay for detection of nucleic acids in plasma is reported. The proposed assay features an array of four polyvinylidene fluoride (PVDF) membranes impregnated with cationic poly (3-alkoxy-4-methylthiophene) (PT) as an optical reporter. The sensing strategy is based on monitoring the changes in optical properties of PT, upon complexation with target nucleic acids in the presence and in the absence of their corresponding complementary peptide nucleic acids (PNAs). As a proof of concept, the proposed methodology is validated using two biomarkers; lung cancer associated microRNA (mir21) and hepatitis B virus DNA (HBV-DNA). The flow-through colorimetric assay enabled detection of mir21 and HBV-DNA in plasma without requiring tedious sample pre-treatment and clean up protocols. Colorimetric responses for mir21 and HBV-DNA were obtained at nanomolar concentrations over five orders of magnitudes (from 1 nM to 10 mu M), with a limit of detection of -0.6 nM and -2 nM in DI water and plasma, respectively. A logic gate system was developed to utilize the colorimetric assay responses as inputs for discrimination of mir21 and HBV-DNA and subsequently to obtain a profile of nucleic acids in samples that exceed respective clinical threshold limits, thereby enabling rapid and point of care (POC) disease diagnosis. Furthermore, the proposed methodology can be utilized for detection of a large number of nucleic acids in plasma by extending the array of PT impregnated membranes incorporated with their corresponding complementary PNAs. (C) 2019 Elsevier B.V. All rights reserved.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; Yıldız, Ümit Hakan; Yücel, Müge; Özçelik, Serdar; Tüncel, Özge; Özenler, Sezer; Kaya, Hakan; Tüncel, Özge; Özçelik, Serdar; Yıldız, Ümit Hakan; 04.01. Department of Chemistry; 04.03. Department of Molecular Biology and Genetics; 01. Izmir Institute of Technology; 04. Faculty of ScienceThis 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: 18Citation - Scopus: 19Hand-Held Volatilome Analyzer Based on Elastically Deformable Nanofibers(American Chemical Society, 2018) Yücel, Müge; Akın, Osman; Yıldız, Ümit Hakan; Akduman, İbrahim; Palaniappan, Alagappan; Liedberg, Bo; Hızal, Gürkan; İnci, Fatih; Yıldız, Ümit Hakan; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyThis study reports on a hand-held volatilome analyzer for selective determination of clinically relevant biomarkers in exhaled breath. The sensing platform is based on electrospun polymer nanofiber-multiwalled carbon nanotube (MWCNT) sensing microchannels. Polymer nanofibers of poly(vinylidene fluoride) (PVDF), polystyrene (PS), and poly(methyl methacrylate) (PMMA) incorporated with MWCNT exhibits a stable response to interferences of humidity and CO2 and provides selective deformations upon exposure of exhaled breath target volatilomes acetone and toluene, exhibiting correlation to diabetes and lung cancer, respectively. The sensing microchannels "P1" (PVDF-MWCNT), "P2" (PS-MWCNT), and "P3" (PMMA-MWCNT) are integrated with a microfluidic cartridge (μ-card) that facilitates collection and concentration of exhaled breath. The volatilome analyzer consists of a conductivity monitoring unit, signal conditioning circuitries and a low energy display module. A combinatorial operation algorithm was developed for analyzing normalized resistivity changes of the sensing microchannels upon exposure to breath in the concentration ranges between 35 ppb and 3.0 ppm for acetone and 1 ppb and 10 ppm for toluene. Subsequently, responses of volatilomes from individuals in the different risk groups of diabetes were evaluated for validation of the proposed methodology. We foresee that proposed methodology provides an avenue for rapid detection of volatilomes thereby enabling point of care diagnosis in high-risk group individuals.Article Citation - WoS: 32Citation - Scopus: 32Luminescent Device for the Detection of Oxidative Stress Biomarkers in Artificial Urine(American Chemical Society, 2018) Ammanath, Gopal; Yıldız, Ümit Hakan; Palaniappan, Alagappan; Liedberg, Bo; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyA luminescent paper-based device for the visual detection of oxidative stress biomarkers is reported. The device consists of a polyvinylidene fluoride membrane impregnated with poly(3-alkoxy-4-methylthiophene) (PT) for colorimetric detection. 8-hydroxy-2′-deoxyguanosine (8-OHdG), a biomarker associated with oxidative stress, is used as a model system for validating the proposed methodology. The detection strategy is based on monitoring the changes in optical properties of PT associated with its conformational changes upon interaction with an aptamer in the presence and in the absence of 8-OHdG. Fluorometric and colorimetric monitoring revealed linear responses for 8-OHdG concentrations between 50 pM and 500 nM (∼14 pg/mL to 140 ng/mL), with limits of detection of ∼300 pM and ∼350 pM, respectively for (n = 3). Colorimetric responses in artificial urine ascertained rapid, sensitive, and selective detection of 8-OHdG at clinically relevant (pM to nM) concentration levels. Furthermore, the proposed methodology enables point-of-care diagnostics for oxidative stress without requiring sophisticated instrumentation.Article Citation - WoS: 56Citation - Scopus: 55A Bodipy-Based Fluorescent Probe To Visually Detect Phosgene: Toward the Development of a Handheld Phosgene Detector(John Wiley and Sons Inc., 2018) Sayar, Melike; Karakuş, Erman; Emrullahoğlu, Mustafa; Yıldız, Büşra; Yıldız, Ümit Hakan; Yıldız, Ümit Hakan; 04.01. Department of Chemistry; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of TechnologyA boron-dipyrromethene (BODIPY)-based fluorescent probe with a phosgene-specific reactive motif shows remarkable selectivity toward phosgene, in the presence of which the nonfluorescent dye rapidly transforms into a new structure and induces a fluorescent response clearly observable to the naked eye under ultraviolet light. Given that dynamic, a prototypical handheld phosgene detector with a promising sensing capability that expedites the detection of gaseous phosgene without sophisticated instrumentation was developed. The proposed method using the handheld detector involves a rapid response period suitable for issuing early warnings during emergency situations.Conference Object Citation - Scopus: 2Utilization of Near Ir Absorbing Gold Nanocolloids by Green Synthesis(Trans Tech Publications, 2018) Elveren, Beste; Yıldız, Ümit Hakan; Yıldız, Ümit Hakan; Arslan Yıldız, Ahu; 04.01. Department of Chemistry; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe rapid developments in nanoscience, and its applications on biomedical areas have a large impact on drug delivery, tissue engineering, sensing, and diagnosis. Gold is widely investigated nanomaterial for the last couple of decades, since it has unique surface properties and very low toxicity to biological environment. In this work, we present a novel synthesis of gold nanoparticles (GNPs) exhibiting both visible and near-IR absorbance without agglomeration. The surface of GNPs were analyzed by routine methods and the binding kinetics were investigated by Surface Plasmon Resonance (SPR) Spectroscopy. The unique optical properties of near-IR asorbing GNP colloids hold promise for biological applications.Conference Object Citation - WoS: 1Citation - Scopus: 4Polymer Nanofiber-Carbon Nanotube Network Generating Circuits(SPIE, 2018) Mutlu, Mustafa Umut; Akın, Osman; Yıldız, Ümit Hakan; Mutlu, Mustafa Umut; 03.09. Department of Materials Science and Engineering; 04.01. Department of Chemistry; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe polymer nanofiber carbon nanotube (CNT) based devices attracts attention since they promise high performance for next generation devices such as wearable electronics, ultra-light weighted appliances and foldable devices. This abstract describes the utilization of polymer nanofibers and CNT as major component of low cost foldable photo-resistor. We use polymer nanofiber as template guiding CNTs to generate nanocircuits and conductive sensing network. The controlled combination of CNTs and polymer nanofibers provide opportunities for device miniaturization without loss of performance. The nanofiber-CNT network based photo-resistor exhibits broad band response 400 to 1600 nm that holding promises for ultra-thin devices and new sensing platforms.Conference Object Citation - Scopus: 2Fabrication of Polymer Nanofiber-Conducting Polymer Fabric and Noncontact Motion Sensing Platform(Trans Tech Publications, 2018) Mutlu, Mustafa Umut; Akın, Osman; Demir, Mustafa Muammer; Yıldız, Ümit Hakan; Mutlu, Mustafa Umut; Yıldız, Ümit Hakan; 03.09. Department of Materials Science and Engineering; 04.01. Department of Chemistry; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyConductive polymer-electrospun polymer nanofiber network was combined to host iron oxide nanoparticles providing micrometer thick sensing interface. The sensor has fabricated as freestanding fabric exhibiting 10 to 100 KOhm base resistivity upon bias applied. The moving object has been sensed through the electrostatic interactions between fibers and object. The sensing range has been found to be 1-5 cm above the surface of fabric. By the controlled combination of conductive polymers electrospun polymer nanofibers effective device miniaturization has been provided without loss of performance. The noncontact motion sensor platform has unique flexibility and light weight holding a potential for wearable sensor technology.Article Citation - WoS: 44Citation - Scopus: 53Smart Phone Assisted Detection and Quantification of Cyanide in Drinking Water by Paper Based Sensing Platform(Elsevier Ltd., 2017) İncel, Anıl; Akın, Osman; Demir, Mustafa Muammer; Yıldız, Ümit Hakan; Demir, Mustafa Muammer; Çağır, Ali; Yıldız, Ümit Hakan; 04.01. Department of Chemistry; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyAn organometallic dye, europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) and gold nanoparticles (Au NPs) impregnated paper based sensor platform have been utilized for development of fluorescence turn-on cyanide assay in aqueous media. The ordinary filter paper with 6 μ m pore size were employed as solid support that facilitates impregnation of EuD4TEA and gold nanoparticles and provides durability. Detection mechanism relying on two processes (i) dissolution of gold nanoparticles causing fluorescence recovery and (ii) ligand exchange of triethyl amine with CN group stimulating cyanide specific fluorescence enhancement. The paper platform exhibit naked eye distinguishable color transition upon CN− addition from 10−2 to 10−12 M. To standardize the methodology a homemade image processing algorithm has been developed that enabling calibration of color change and quantify CN− concentration. The described algorithm is applicable to Android smart phones and facilitate transforming these devices into a quantitative cyanide detector. The overall methodology provides instrument free cyanide detection and therefore rapid control of water quality and safety at off-field conditions.