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Öğe Biosensing Applications of Modified Core-Shell Magnetic Nanoparticles(2012) Ozdemir C.; Akca O.; Medine E.I.; Demirkol D.O.; Unak P.; Timur S.Fe 3O 4 magnetic nanoparticles (MNPs) were synthesized and silanized to form a core-shell (Fe 3O 4-SiO 2) structure. Afterwards, surface modification with amino silane was carried out to produce amino groups on the MNPs for the biomolecule immobilization. In order to test the performance of amino functional MNPs as immobilization platform in biosensing applications, glucose oxidase was immobilized on the surface via glutaraldehyde. Obtained Bio-MNPs were then fixed onto the carbon paste electrode by the aid of magnetic force and used as the working electrode during the amperometric measurements at -0. 7 V versus Ag/AgCl. After optimization of some parameters affecting the biosensor performance, analytical characterization was carried out. Linearity was found in the range of 0. 25-2. 0 mM glucose and defined by the equation of y = 8. 366x + 1. 819, (R 2 = 0. 996). Proposed biosensor was then applied for the glucose analysis in various beverages. Finally, data were compared with a commercial enzyme assay kit based on spectrophotometric Trinder reaction as a reference method. © 2011 Springer Science+Business Media, LLC.Öğe Electrochemical glucose biosensing by pyranose oxidase immobilized in gold nanoparticle-polyaniline/AgCl/gelatin nanocomposite matrix(2010) Ozdemir C.; Yeni F.; Odaci D.; Timur S.A novel pyranose oxidase (PyOx) biosensor based on gold nanoparticles (AuNPs)-polyaniline(PANI)/AgCl/gelatin nanocomposite has been developed for the glucose detection. PyOx was immobilized on the surface of glassy carbon electrode (GCE) via the nanocomposite matrix. The electrode surface was imaged by scanning electron microscopy (SEM). Amperometric detection of the consumed oxygen during the enzymatic reaction was monitored at -0.7 V. After optimization studies, analytical characterization of the biosensor was carried out. The linear response of the AuNPs-AgCl/PANI/gelatin modified PyOx biosensor is found to be from 0.05 to 0.75 mM glucose with the equation of y = 2.043x + 0.253; R2 = 0.993. Finally, proposed biosensor was used to analyze glucose content in real samples. Obtained data from the biosensing system was compared with a commercial enzyme assay kit based on spectrophotometric Trinder reaction as a reference method. © 2009 Elsevier Ltd. All rights reserved.Öğe Gold nanoparticle modified conducting polymer of 4-(2,5-di(thiophen-2-yl)- 1H-pyrrole-1-l) benzenamine for potential use as a biosensing material(2011) Tuncagil S.; Ozdemir C.; Demirkol D.O.; Timur S.; Toppare L.Gold nanoparticle (AuNP) modified conducting polymer of 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzenamine (SNS-NH2) was used as the biosensing platform for glucose analysis. Electrochemical measurements were carried out by following the consumed oxygen due to the enzymatic reaction of glucose oxidase (GOx) at -0.7 V vs Ag/AgCl. Optimisation of pH, enzyme loading, stability experiments were carried out. Effect of NP was investigated by monitoring the signal responses at different AuNP sizes and amounts. A linear relation of y = 1.597x + 0.264 (R2 = 0.993) was found for glucose concentrations between 0.002 and 5.0 mM. The analytical characteristics of the system were also evaluated for glucose determination in flow injection analysis (FIA) mode. Finally, the system was checked for glucose detection on real samples. © 2011 Elsevier Ltd. All rights reserved.Öğe Offline glucose biomonitoring in yeast culture by polyamidoamine/ cysteamine-modified gold electrodes(2011) Yuksel M.; Akin M.; Geyik C.; Demirkol D.O.; Ozdemir C.; Bluma A.; Höpfner T.; Beutel S.; Timur S.; Scheper T.This article deals with the use of pyranose oxidase (PyOx) and glucose oxidase (GOx) enzymes in amperometric biosensor design and their application in monitoring fermentation processes with the combination of flow injection analysis (FIA). The amperometric studies were carried out at -0.7 V by following the oxygen consumption due to the enzymatic reactions for both batch and FIA modes. Optimization studies (enzyme amounts and pH) and analytical parameters such as linearity, repeatability, effect of interference, storage, and operational stabilities have been studied. Under optimized conditions, for the PyOx-based biosensor, linear graph was obtained from 0.025 to 0.5 mM glucose in phosphate buffer (50 mM) at pH 7.0 with the equation of y = 3.358x + 0.028 and R2 = 0.998. Linearity was found to be 0.01-1.0 mM in citrate buffer (50 mM and pH 4.0) with the equation of y = 1.539x + 0.181 and R2 = 0.992 for the GOx biosensor. Finally, these biosensor configurations were further evaluated in a conventional flow injection system. Results from batch experiments provide a guide to design sensitive, stable, and interference-free biosensors for FIA mode. Biosensor stability, dynamic range, and repeatability were also studied in FIA conditions, and the applicability for the determination of glucose in fermentation medium could be successfully demonstrated. The FIA-combined glucose biosensor was used for the offline monitoring of yeast fermentation. The obtained results correlated well with HPLC measurements. © 2011 American Institute of Chemical Engineers.Öğe Propofol orchestrates long non-coding RNAs in MCF7 cells, unraveling new avenues for breast cancer intervention(Elsevier Masson s.r.l., 2024) Biray Avci C.; Edgunlu T.G.; Suzek T.; Ozates N.P.; Goker Bagca B.; Demirtas Bilgic A.; Ozdemir C.Long non-coding RNAs (lncRNAs) play a dynamic role in gene expression regulation and serve as potential therapeutic targets in breast cancer. The anticancer effect of propofol, an anesthetic agent, has been proven, but its interaction with lncRNAs has not been adequately investigated. This study aims to reveal the interactions between propofol and lncRNAs and contribute to the understanding of its therapeutic potential in the treatment of breast cancer. We evaluated the effects of propofol on cell viability, apoptosis, and mitochondrial membrane potential in MCF7 cells. The study used qRT-PCR to analyze cancer-related lncRNA expressions following propofol treatment; this was supported by RNA-RNA interaction predictions and in silico functional analysis using selected datasets and the R cluster Profiler GSEABase package. Propofol showed a cytotoxic effect at higher doses in MCF7 breast cancer cells, inducing necrosis. Propofol regulated (IGF2-AS, MRPL23-AS1, PANDAR, HULC) and down-regulated (IWT1-AS, HOXA-AS2, H19, GACAT1, MIAT) the expression levels of various lncRNAs in MCF7 cells. Our research revealed complex interactions of MALAT1 lncRNA with both upregulated and downregulated genes. Additionally, three rRNA genes (LSU-rRNA, RNA45SN3, and SSU-rRNA) were identified to interact with both groups of lncRNAs. Propofol potentially targets chemotherapy resistance by regulating UCA1, LINC-RoR1, and MEG3. Wikipathways' pathway enrichment analysis identified two downregulated lncRNAs, UCA1 and LINC-RoR1, and an upregulated MEG3, implicated in lncRNA-mediated chemotherapeutic resistance mechanisms. Our study illuminates the intricate interplay of lncRNAs and their potential contribution to propofol's anti-cancer effects in breast cancer, offering new avenues for therapeutic exploration and advancement. © 2024Öğe Studies on the morphology, anatomy and ecology of ophrys lutea cav. subsp. minor (Guss.) O. Danesch & E. Danesch ex Gölz & H.R. Reinhard (orchidaceae) in Turkey(Pakistan Botanical Society, 2014) Durmuskahya C.; Ozdemir C.; Bozdag B.; Öztürk M.In this study, morphological, anatomical and ecological characteristics of Ophrys lutea subsp. minor in Turkey were investigated. The plant material was collected from 30 different populations during 2010-2013. In all 19 morphological and 20 anatomical features were investigated, and habitat characteristics recorded. The soil samples were also collected from the plant sampling sites and subjected to an analysis for 18 characteristics. The minimum plant length was 69 mm and maximum 323 mm, minimum length of underground part was 29 mm, and maximum 49 mm, and the number of leaves varied between 1-10. The ecological characteristics revealed that O. lutea subsp. minor flourishes well from sea level to 800 m, and the most common habitats of O. lutea subsp. minor are rocky limestones, phrygana, macchie, olive gorves, woodland margins.Öğe X band patch array antenna design for marine radar application(Institute of Electrical and Electronics Engineers Inc., 2018) Pehlivan M.; Asci Y.; Yegin K.; Ozdemir C.Horizontally polarized patch antenna array design is proposed for frequency modulated continuous wave (FMCW) marine radar applications. The array consists of series-parallel fed 96 elements printed on microwave substrate. The array configuration is optimized for minimum line loss and maximum aperture efficiency. The target frequency band is 9.3-9.4 GHz. Antenna parameters such as return loss, peak gain, half-power beam width and side-lobe levels are presented for marine radar applications. © 2018 Warsaw University of Technology.