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Öğe Aptasensor for Impedimetric Detection of Lysozyme(Humana Press Inc., 2023) Eksin, E.; Senturk, H.; Erdem, A.The impedimetric detection of a protein, lysozyme (LYS), was carried out herein by aptamer-immobilized single-use pencil graphite electrodes (PGEs). The aptamer was immobilized onto electrochemically activated surface of electrode without using any chemical agents, or any types of nanomaterials. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were applied to analyze the electrochemical behavior of unmodified PGE and aptamer immobilized PGE. The interaction of aptamer with its target protein, LYS, was then investigated by EIS. The limit of detection for LYS was found to be 1.44 ?g/mL (equals to 100.65 nM). The developed aptasensor specific to LYS presented high selectivity against to bovine serum albumin and thrombin. © 2023, The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.Öğe The bronze shields found at the Ayanis fortress (Van region, Turkey): manufacturing techniques and corrosion phenomena(Springer, 2010) Ingo, G. M.; Cilingiroglu, A.; Faraldi, F.; Riccucci, C.; Casaletto, M. P.; Erdem, A.; Batmaz, A.The manufacturing techniques, chemical composition and corrosion products grown on archaeological bronze shields found during the excavation of the Ayanis fortress (Lake Van region, Eastern Anatolia, Turkey) were studied by means of the combined use of scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and optical microscopy (OM) techniques. The shields are dated back to 673-645 BC and in some cases are decorated with cuneiform inscriptions and ornaments representing various animals, such as lions and bulls. The micro-chemical and structural results show the presence of corrosion products constituted by copper carbonates (azurite and malachite), cuprite and dangerous chlorine-based compounds (nantokite, atacamite, clinoatacamite and paratacamite) due to the Cl-enriched soil of Ayanis. Furthermore, the results show that the bronze shields are coated with a Sn-enriched thin layer, likely due to an intentional tinning process carried out in ancient times to achieve a silver-like finish. Analytical data show an inter-granular corrosion phenomenon that heavily corroded the boundaries of the large equiassic grains inducing mechanical weakness. This latter phenomenon was induced by the repeated cycles of mechanical work and annealing thermal treatments carried out to restore the ductility and malleability of the alloy. Such processing caused the crystallisation and growth of the flattened grains, as well as impurities segregation phenomena along grain boundaries, thus enhancing the inter-granular long-term corrosion.Öğe Carbon Nanofiber-Ionic Liquid Nanocomposite Modified Aptasensors Developed for Electrochemical Investigation of Interaction of Aptamer/Aptamer–Antisense Pair with Activated Protein C(MDPI, 2023) Maral, M.; Erdem, A.Selective and sensitive detection of human activated protein C (APC) was performed herein by using carbon nanofiber (CNF) and ionic liquid (IL) composite modified pencil graphite electrode (PGE) and electrochemical impedance spectroscopy (EIS) technique. A carbon nanomaterial-based electrochemical aptasensor was designed and implemented for the first time in this study for the solution-phase interaction of DNA-Apt with its cognate protein APC as well as APC inhibitor aptamer–antidote pair. The applicability of this assay developed for the determination of APC in fetal bovine serum (FBS) and its selectivity against different proteins (protein C, thrombin, bovine serum albumin) was also examined. CNF-IL modified aptasensor specific to APC provided the detection limit as 0.23 ?g/mL (equal to 3.83 nM) in buffer medium and 0.11 ?g/mL (equal to 1.83 nM) in FBS. The duration of the proposed assay from the point of electrode modification to the detection of APC was completed within only 55 min. © 2023 by the authors.Öğe Electrochemical Behavior of Disposable Electrodes Prepared by Ion Beam Based Surface Modification for Biomolecular Recognition(Amer Inst Physics, 2009) Erdem, A.; Urkac, E. Sokullu; Karadeniz, H.; Caliskan, A.; Oks, E.; Nikolayev, A.; Oztarhan, A.; McDaniel, FD; Doyle, BLMany important technological advances have been made in the development of technologies to monitor interactions and recognition events of biomolecules in solution and on solid substrates. The development of advanced biosensors could impact significantly the areas of genomics, proteomics, biomedical diagnostics and drug discovery. In the literature, there have recently appeared an impressive number of intensive designs for electrochemical monitoring of biomolecular recognition. Herein, the influence of ion implanted disposable graphite electrodes on biomolecular recognition and their electrochemical behaviour was investigated.Öğe Electrochemical detection of interaction between daunorubicin and DNA by hybrid nanoflowers modified graphite electrodes(Elsevier B.V., 2020) Findik, M.; Bingol, H.; Erdem, A.In this study, two types of hybrid nanoflowers (NFs) modified disposable electrodes were developed to investigate the electrochemical behavior of anticancer drug-DNA interaction. Biocompatible hybrid NFs were synthesized by amino acids (L-glutamic acid and L-cysteine) via a simple, rapid and cost-effective methods. Structural characterizations of the synthesized hybrid NFs were performed with Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), while morphological characterizations were performed using scanning electron microscopy (SEM) and energy diffuser X-ray (EDX) spectroscopy techniques. As the sensing platform in electrochemical studies, pencil graphite electrode (PGE) has been used because of its advantages such as low cost, easy-to-handle, portable and disposable. After PGEs modified with NFs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques, differential pulse voltammetry (DPV) technique was used in the determination of calf thymus double stranded DNA (ctdsDNA) and also daunorubicin (DNR) as well as DNA-DNR interaction. The detection limits as a result of ctdsDNA determination were found to be 0.93 ?g/mL by using L-cysteine NFs modified PGE (c-NFs-PGE) and 2.37 ?g/mL by using L-glutamic acid modified PGE (ga-NFs-PGE). The detection limits obtained for the determination of DNR were found as 2.93 ?M and 2.06 ?M with c-NFs-PGE and ga-NFs-PGE, respectively. The optimum interaction time between DNR and ctdsDNA was determined by c-NFs-PGE, which showed higher sensitivity performance against oxidation of guanine signals. © 2020Öğe Electrochemical DNA biosensors developed for the monitoring of biointeractions with drugs: a review(TUBITAK, 2023) Erdem, A.; Şentürk, H.; Yildiz, E.; Maral, M.; Yildirim, A.; Bozoğlu, A.; Kivrak, B.The interaction of drugs with DNA is important for the discovery of novel drug molecules and for understanding the therapeutic effects of drugs as well as the monitoring of side effects. For this reason, many studies have been carried out to investigate the interactions of drugs with nucleic acids. In recent years, a large number of studies have been performed to electrochemically detect drug–DNA interactions. The fast, sensitive, and accurate results of electrochemical techniques have resulted in a leading role for their implementation in this field. By means of electrochemical techniques, it is possible not only to demonstrate drug–DNA interactions but also to quantitatively analyze drugs. In this context, electrochemical biosensors for drug–DNA interactions have been examined under different headings including anticancer, antiviral, antibiotic, and central nervous system drugs as well as DNA-targeted drugs. An overview of the studies related to electrochemical DNA biosensors developed for the detection of drug–DNA interactions that were reported in the last two decades in the literature is presented herein along with their applications and they are discussed together with their future perspectives. © TÜBİTAK.Öğe ELECTROCHEMICAL SENSOR TECHNOLOGY BASED ON NANOMATERIALS FOR BIOMOLECULAR RECOGNITIONS(Springer, 2008) Erdem, A.; Vaseashta, A; Milhailescu, INThere have been many important technological advances for development of electrochemical approaches to monitor biomolecular interactions and recognition events ill Solution and at solid substrates. This investigation describes how novel surfaces modified with nanomaterials can produce selective and sensitive electrochemical DNA sensors and biological recognition Surfaces.Öğe First ground-based photometry and light-curve analysis of the eccentric eclipsing binary V744 Cas(Wiley-V C H Verlag Gmbh, 2006) Bulut, I.; Cicek, C.; Erdem, A.; Bakis, V.; Demircan, O.; Degirmenci, O. L.The first ground-based BVR photometric observations of the recently discovered eclipsing binary V744 Cas are presented. From these measurements, timings for two primary and one secondary minima have been calculated. The light curves of the system were analyzed by using the Wilson-Devinney program. The analysis shows that the system is detached with two similar components of spectral type A2V, and the orbit is eccentric (e = 0.0662 +/- 0.0005). The longitude of the periastron (w) was found significantly different for two different light curves (ours and that of Hipparcos), which is strongly suggestive of an apsidal motion with a period of about 425 +/- 68 yr. This makes V744 Cas an important candidate for studies of apsidal motions. The first estimate of the absolute dimensions place the system close to the terminal age of the main sequence (TAMS) in the HR diagram. The distance from the spectroscopic parallax (d = 740 +/- 10 pc) was found to be slightly larger than the Hipparcos distance of d = 610 +/- 400 pc. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Öğe Gold nanoparticle/polymer nanocomposite for highly sensitive drug-DNA interaction(Royal Soc Chemistry, 2015) Kuralay, F.; Erdem, A.The interaction of the anticancer drug mitomycin C (MC) and DNA immobilized on gold a nanoparticle/polyvinylferrocenium (AuNP/PVF+) coated electrode is presented. This is the first attempt to prepare a biocompatible nanoparticle/redox polymer composite in a one-step and easy electropolymerization procedure and then use the coated electrode for MC-DNA interaction. The prepared electrode exhibits high sensitivity for the investigation of drug-DNA interaction.Öğe Hybrid nanoflowers modified pencil graphite electrodes developed for electrochemical monitoring of interaction between Mitomycin C and DNA(Elsevier B.V., 2021) Findik, M.; Bingol, H.; Erdem, A.In the present study, biocompatible hybrid nanoflowers (NFs) were synthesized by amino acids (glycine, L-lysine) via a simple, rapid and cost-effective methods. NFs were characterized by using FT-IR, Raman spectroscopy, XPS, SEM and EDX techniques. Modified pencil graphite electrode (PGE) surfaces with well-defined NFs were developed to electrochemical monitoring of calf thymus double stranded DNA (ctdsDNA) using differential pulse voltammetry (DPV) for the first time. SEM, EDX, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods were used to characterize the surfaces obtained after modification. In comparison to L-lysine NFs (LNFs-PGE), glycine NFs (GNFs-PGE) exhibited a higher sensitivity performance towards the oxidation of guanine moiety signals. The interaction time between anticancer drug Mitomycin C (MC) and ctdsDNA was aslo investigated with GNFs-PGE. © 2020 Elsevier B.V.Öğe Implementation of 3D printing technologies to electrochemical and optical biosensors developed for biomedical and pharmaceutical analysis(Elsevier B.V., 2023) Erdem, A.; Yildiz, E.; Senturk, H.; Maral, M.Three-dimensional (3D) printing technology has been applied in many areas. In recent years, new generation biosensorshave been emerged with the progress on 3D printing technology (3DPT). Especially in the development of optical and electrochemical biosensors, 3DPT provides many advantages such as low cost, easy to manufacturing, being disposable and allow point of care testing. In this review, recent trends in the development of 3DPT based electrochemical and optical biosensors with their applications in the field of biomedical and pharmaceutical are examined. In addition, the advantages, disadvantages and future opportunities of 3DPT are discussed. © 2023 Elsevier B.V.Öğe Ionic Liquid Modified Single-use Electrode Developed for Voltammetric Detection of miRNA-34a and its Application to Real Samples(Wiley-VCH Verlag, 2020) Yaralı, E.; Kanat, E.; Erac, Y.; Erdem, A.The ionic liquid (IL) modified chemically activated (CA) pencil graphite electrodes (PGEs) were developed for label-free voltammetric detection of miRNA-34a, and implemented to the real samples. Firstly, the electrochemical characterization of unmodified PGE, CA-PGE, IL-PGE and IL-CA-PGE was performed by cyclic voltammetry (CV) as well as their DNA binding capacity was studied by electrochemical impedance spectroscopy (EIS) technique. The microscopic characterization of the surface of each electrodes was investigated by scanning electron microscopy (SEM). Differential pulse voltammetry (DPV) technique was used for measuring the oxidation signal of guanine in order to perform a label-free voltammetric monitoring of a full-match hybridization specific to miRNA-34a. The selectivity of biosensor was tested against to miRNA-155, miRNA-660 as well as to the mismatch sequence of miRNA-34a. The further selectivity of this proposed biosensor was studied in the mixture of samples containing miRNA-34a with other miRNAs (1 : 1). The voltammetric detection of miRNA-34a was also explored in the artificial serum medium as fetal bovine serum (FBS) and also in total RNA samples isolated from HUH-7 human hepatocellular carcinoma cell line. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimÖğe Liver involvement in patients with brucellosis: results of the Marmara study(Springer, 2014) Ozturk-Engin, D.; Erdem, H.; Gencer, S.; Kaya, S.; Baran, A. I.; Batirel, A.; Tekin, R.; Celen, M. K.; Denk, A.; Guler, S.; Ulug, M.; Turan, H.; Pekok, A. U.; Mermut, G.; Kaya, S.; Tasbakan, M.; Tulek, N.; Cag, Y.; Inan, A.; Yalci, A.; Ataman-Hatipoglu, C.; Gonen, I.; Dogan-Celik, A.; Bozkurt, F.; Gulsun, S.; Sunnetcioglu, M.; Guven, T.; Duygu, F.; Parlak, E.; Sozen, H.; Tosun, S.; Demirdal, T.; Guclu, E.; Karabay, O.; Uzun, N.; Gunal, O.; Diktas, H.; Haykir-Solay, A.; Erbay, A.; Kader, C.; Aydin, O.; Erdem, A.; Elaldi, N.; Kadanali, A.; Yulugkural, Z.; Gorenek, L.; Altindis, M.; Bolukcu, S.; Agalar, C.; Ormeci, N.Brucellosis is a zoonotic disease that primarily affects the reticuloendothelial system. But, the extent of liver damage in due course of the disease is unclear. This study included 325 brucellosis patients with significant hepatobiliary involvement identified with microbiological analyses from 30 centers between 2000 and 2013. The patients with a parts per thousand yen5 times of the upper limit of normal for aminotransferases, total bilirubin level a parts per thousand yen2 mg/dl or local liver lesions were enrolled. Clinical hepatitis was detected in 284 patients (87.3 %) and cholestasis was detected in 215 (66.1 %) patients. Fatigue (91 %), fever (86 %), sweating (83 %), arthralgia (79 %), and lack of appetite (79 %) were the major symptoms. Laboratory tests showed anemia in 169 (52 %), thrombocytopenia in 117 (36 %), leukopenia in 81 (25 %), pancytopenia in 42 (13 %), and leukocytosis in 20 (6 %) patients. The most commonly used antibiotic combinations were doxycycline plus an aminoglycoside (n = 73), doxycycline plus rifampicin (n = 71), doxycycline plus rifampicin and an aminoglycoside (n = 27). The duration of ALT normalization differed significantly in three treatment groups (p < 0.001). The use of doxycycline and an aminoglycoside in clinical hepatitis showed better results compared to doxycycline and rifampicin or rifampicin, aminoglycoside, doxycycline regimens (p < 0.05). However, the length of hospital stay did not differ significantly between these three combinations (p > 0.05). During the follow-up, treatment failure occurred in four patients (1 %) and relapse was seen in three patients (0.9 %). Mortality was not observed. Hepatobiliary involvement in brucellosis has a benign course with suitable antibiotics and the use of doxycycline and an aminoglycoside regimen seems a better strategy in select patients.Öğe Nucleic acid based impedimetric biosensors(Elsevier, 2023) Erdem, A.; Eksin, E.; Maral, M.Analytical research related to (bio)sensors has gained an enormous growth since 1990s. Rapid, highly selective, and sensitive techniques to quantify biological and biochemical molecules and other target species are of great importance in biomedical application. Electrochemical biosensors based on impedance technique have been extremely useful for sensing of different types of biological interactions during the past years, due to their high sensitivity and fast response. A variety of sensing platforms in combination with electrochemical impedance spectroscopy as well as devices have been developed and still under progress. This chapter is focused on the development of impedimetric biosensors as functional sensing platforms for detection of nucleic acids by means of their excellent features such as portability, sensitivity, cost-effectiveness, easy to use and miniaturization, label-free operation, and on-site analysis. © 2023 Elsevier Ltd. All rights reserved.
