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    A critical review of molecularly imprinted polymer technology for aflatoxin sensing: Current status and future directions
    (Elsevier, 2026) Cetinkaya, Ahmet; Kaya, S. Irem; Demirbakan, Burcak; Unal, Mehmet Altay; Sezginturk, Mustafa Kemal; Ozkan, Sibel A.; Altuntas, Evrim Gunes
    Since the first discovery and identification of aflatoxins almost 70 years ago, their occurrence, potential risks, and health hazards remain of great importance. Therefore, several chromatography-, colorimetry-, and immunoassay-based analytical applications for aflatoxin detection are reported in the literature. Molecularly imprinted polymers (MIPs) have attracted considerable interest in sensor design due to their unique potential as synthetic recognition elements, providing high selectivity and excellent stability. These features help overcome the disadvantages of conventional sensing systems. The ongoing advancement of MIP-based sensors presents new opportunities for future applications and offers a reliable and versatile approach to meet the growing demands of current analytical research. This review focuses on studies published since 2023 concerning the detection of aflatoxins using MIP-based sensors, which hold a prominent and critical position in the literature. Additionally, this review addresses several limitations of MIP-based sensors, particularly in the context of aflatoxin detection, and discusses proposed solutions to overcome these challenges. Lastly, current advancements and future expectations in the topic are also highlighted.
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    A New Approach to Synthesis of Highly Dispersed Gold Nanoparticles via Glucose Oxidase-Immobilized Hydrogel and Usage in The Reduction of 4-Nitrophenol
    (Wiley-V C H Verlag Gmbh, 2020) Ozay, Hava; Tarimeri, Nur; Gungor, Zeynep; Demirbakan, Burcak; Ozcan, Burcu; Sezgintürk, Mustafa Kemal; Özay, Özgür
    In this study, for the first time in the literature, synthesis of Au(0) nanoparticles supported by a crosslinked gel structure was performed via enzyme-mediated reduction of Au(III) ions without using any chemical reductant. In our newly-developed method, glucose oxidase enzymes immobilized in the crosslinked gelatine structure ensured simultaneous reduction of the Au(III) ions diffused within the gel to Au(0). The Au@Gel obtained was structurally characterised with TEM (Transmission electron microscopy), EDX (Energy dispersive X-ray analysis) elemental mapping, XPS (X-Ray photoelectron spectroscopy) and XRD (X-Ray Diffraction) analyses. The catalytic activity of Au(0) particles with nearly 8 nm size in the Au@Gel was investigated for the reduction of 4-nitrophenol (4-NP) as a model compound in the presence of NaBH(4)as reducing agent. The activation parameters for the reduction reaction of 4-nitrophenol in the presence of Au@Gel catalyst were determined as E-a= 30.16 kJmol(-), Delta H= 27.52 kJmol(-)and Delta S= -197.45 Jmol(-)K(-). The Au@Gel catalyst system, with good catalytic activity, simultaneously has nearly perfect reusability.
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    A novel electrochemical immunosensor based on disposable ITO-PET electrodes for sensitive detection of PAK 2 antigen
    (Elsevier Science Sa, 2019) Demirbakan, Burcak; Sezgintürk, Mustafa Kemal
    In the present work, we have developed a novel electrochemical immunosensor based on modified disposable ITO-PET (indium tin oxide - polyethylene terephthalate) electrodes for PAK-2 (p21-activated kinase 2) early detection. An ITO-PET electrode surface was modified with 3-cyanopropyl trimethoxysilane (3-CPTMS), which formed self-assembled monolayers (SAMs). PAK2 immunosensing was performed by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) techniques, square wave voltammetry (SWV) and a single frequency impedance (SFI) technique utilized for specific interaction between the anti-PAK2 and PAK2 antigen. Further, the morphological characterization of each ITO electrode surface was observed by scanning electron microscopy (SEM). All parameters such as 3-CPTMS concentration, antibody concentration and antibody incubation time were optimized. Analytical characteristics of the proposed immunosensor such as linear determination range, repeatability, reproducibility, regeneration, storage life and surface coverage of immunosensors were determined. The PAK2 electrochemical immunosensor performed flawlessly with a wide determination range (from 0.05 pg mL(-1) to 2.5 pg mL(-1)) and low limits of detection (0.0252 pg mL(-1)) and of quantification (0.0842 pg mL(-1)) The artificial and human serum samples were tested to verify the viability of the proposed immunosensor. (C) 2019 Elsevier B.V. All rights reserved.
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    A novel ultrasensitive immunosensor based on disposable graphite paper electrodes for troponin T detection in cardiovascular disease
    (Elsevier, 2020) Demirbakan, Burcak; Sezgintürk, Mustafa Kemal
    Troponin T, which is a biomarker of cardiovascular disease, is vital for acute myocardial infarction (AMI). AMI is the most well-known cause of death in the world. In the present work, we designed a novel immunosensor using disposable, cheap, and very conductive graphite paper electrodes (GP). The proposed immunosensor was modified with hydrochloric acid (HCl) for immobilization of anti-TnT antibody. After carboxyl group formation on the surface, the GP electrodes were incubated with EDC/NHS pair as a cross-linker. Electrochemical impedance spectroscopy (EIS), single frequency impedance (SFI), cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were used for electrochemical characterization of the label-free immunosensor. Furthermore, the fabrication process of the proposed immunosensor was examined by using scanning electron microscopy (SEM). The proposed electrochemical immunosensor had a wide detection range (0.5 fg - 1000 fg/mL), and low limit of detection (LOD) and low limit of quantification (LOQ) at 1.28 fg/mL and 4.29 fg/mL, respectively. The designed immunosensor exhibited very good sensitivity, reproducibility, repeatability, reusability and long storage life. Additionally, the immunosensor was successfully applied to detection of TnT in human serum.
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    Öğe
    A sensitive and disposable indium tin oxide based electrochemical immunosensor for label-free detection of MAGE-1
    (Elsevier Science Bv, 2017) Demirbakan, Burcak; Sezgintürk, Mustafa Kemal
    MAGE-1 (MAGE, for melanoma antigen), was identified by virtue of its processing and cell surface expression as a tumor-specific peptide bound to major histocompatibility complexes which was reactive with autolytic T cells. 3-Glycidoxypropyltrimethoxysilane (3-GOPS) is frequently employed for the preparation of dense heterometal hybrid polymers which are used, e.g., for hard coatings of organic polymers and contact lens materials in the optical industry. In this study, we have improved a new immunological biosensor with indium tin oxide (ITO). Then, Anti-MAGE-1 antibody was covalently immobilized with 3-GOPS which formed a self-assembled monolayers (SAMs) on modified ITO electrodes. Analytical characteristics such as square wave voltammetry, linear determination range, repeatability, reproducibility and regeneration of biosensors are determined. All characterization steps are monitored by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV). The developed biosensor has wide determination range (0.5 fg-15 fg/mL). To investigate long shelf life of the fabricated biosensor, the immunosensors were stored at 4 degrees C for periods ten weeks. Futhermore, binding kinetics of MAGE1 to antiMAGE-1 is monitored by single frequency technique in real time. Additionally, Kramer's-Kronig transform was used to understand whether the impedance spectra of biosensor system are affected from the variation that occurred because of external factor. Morphological characteristics of constructed biosensor were observed by scanning electron microscopy. Real human serum samples were also analyzed by the proposed biosensor, successfully. A commercial ELISA kit was also used as a reference method to validate the results obtained by the biosensor. Finally, this biosensor was tried in real blood sample and that showed it could be utilized in clinical applications. This biosensor can be preferred due to it has a wide linear range and it can be prepared easily.
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    Öğe
    An electrochemical immunosensor based on graphite paper electrodes for the sensitive detection of creatine kinase in actual samples
    (Elsevier Science Sa, 2022) Demirbakan, Burcak; Sezgintürk, Mustafa Kemal
    The enzyme creatine kinase (CK) is one of the most well-established biomarkers in cardiovascular disease. For acute myocardial infarction (AMI) diagnosis, CK has a clinical comorbidity rate of 90%. This study has developed a novel electrochemical immunosensor using disposable graphite paper electrodes (GP). The GP electrodes were modified with gold nanoparticles (AuNP) to facilitate CK detection. Afterwards, GP electrodes were covalently immobilized with 6-mercapto-1-hexanol (6-MH), resulting in self-assembled monolayers (SAMs). Then, the electrodes were formed with a 3-Glycidyloxypropyltrimethoxysilane (3-GOPE) agent. Afterwards, the electrodes were immobilized with anti-CK (antibody creatine kinase) protein. In the final immobilization step, BSA (bovine serum albumin) protein was used to block non-covalent interactions. All parameters of the proposed immunosensor were optimized, including concentrations and incubation times. Analytical characteristics such as square wave voltammetry, linear determination range, repeatability, reproducibility, and regeneration of biosensors were determined. All characterization steps were monitored by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV). Moreover, the single frequency impedance (SFI) technique interacted with anti-CK and CK antigens. Furthermore, the proposed immunosensor was characterized using scanning electron microscopy (SEM). The proposed immunosensor exhibited a wide detection range (0.1 -50 pg mL(-1)), and low limit of detection (LOD), and a low limit of quantification (LOQ); 0.045 pg mL(-1) and 0.171 pg mL(-1), respectively. Finally, the developed biosensor was tried in an actual blood sample, which showed it could be utilized in clinical applications.
  • Küçük Resim
    Öğe
    An impedimetric biosensor system based on disposable graphite paper electrodes: Detection of ST2 as a potential biomarker for cardiovascular disease in human serum
    (Elsevier B.V., 2021) Demirbakan, Burcak; Sezgintürk, Mustafa Kemal
    In present study, we developed a highly sensitive, electrochemical immunosensor based on fullerene C60-modified disposable graphite paper (GP) electrode for determination of Suppression of Tumorigenicity 2 (ST2) in human serum. The synthesis of the ST2 immunosensor was monitored with electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) techniques and single frequency impedance (SFI) technique which is utilized for the specific interaction between anti-ST2 and ST2 antigen. Moreover, the morphological alteration of each GP surface was examined by scanning electron microscopy (SEM), SEM-energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). All parameters such as fullerene C60 concentration, antibody concentration and antibody incubation time were optimized. Analytical characteristics such as linear determination range, repeatability, reproducibility, regeneration and surface coverage were determined for the immunosensor. The ST2 electrochemical immunosensor had excellent repeatability, reproducibility and a wide detection range (from 0.1 fg mL−1 to 100 fg mL−1). The proposed immunosensor also had low limit of detection (LOD) and limit of quantification (LOQ) values of 0.124 fg mL−1 and 0.414 fg mL−1, respectively. The proposed immunosensor was applied to real samples to test applicability in clinical practice.