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Öğe A cost-effective and sensitive Au/6-mercaptohexanol/CNBr modified immunosensor approach for adiponectin analysis(Elsevier, 2024) Özcan, BurcuThis research aimed to develop a method for analyzing adiponectin using a label-free impedimetric indium tin oxide-polyethylene terephthalate (ITO-PET) immunosensing system. A simple and stable process to design a bioelectrode modified with gold (Au)/6-mercaptohexanol (6-MH)/cyanogen bromide (CNBr)/anti-adiponectin and its biocompatibility with adiponectin was investigated. The immunosensor performance, optimization tests, and immobilization steps were all monitored and analyzed using Electrochemical Impedance spectroscopy (EIS) and cyclic voltammetry (CV). Scanning Electron microscopy (SEM) examined the surface morphology of this biosensor during its immobilization process. Testing the developed biosensor with real human serum samples allowed for an evaluation of its clinical performance. The proposed immunosensor demonstrated high repeatability, reproducibility (RSD%: 4.37 %), long storage stability, and reusability (preserving 85 % of activity in the third regeneration step), along with a low limit of detection for adiponectin antigen and a wide range of linear values. The sensor suggested a linear detection range of 0.25 pg/mL to 500 pg/mL. The limit of detection (LOD) was found to be 0.20 pg/mL, and the limit of quantification (LOQ) was determined to be 0.66 pg/mL. It appears that the biosensor decorated with Au/6-MH/CNBr could be a good choice for the selective determination of adiponectin protein, according to the statistical data.Öğe A novel and disposable GP- based impedimetric biosensor using electropolymerization process with PGA for highly sensitive determination of leptin: Early diagnosis of childhood obesity(Elsevier, 2021) Özcan, Burcu; Sezgintürk, Mustafa KemalThis study presents a novel, single-use electrochemical biosensor for the leptin biomarker, which may have potential use for early diagnosis of childhood obesity. The graphite paper working electrode was used for the first time in impedimetric biosensors. All immobilization procedure, investigation of the optimal parameters and characterization of biosensors were followed and evaluated using Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV). The Scanning Electron Microscope (SEM) was utilized to visualize the morphology of the electrode surface during the immobilization steps of the immunosensor. Moreover, the characterization of the interactions between anti-leptin and leptin was investigated by using Single Frequency Technique (SFI). The applicability of the designed biosensor for real serum samples was tested for clinical use. It was observed that the biosensor allows high sensitivity in the analyte detection (leptin) in real serum samples. Moreover, it was suggested that the developed biosensor presents advantages such as long shelf life (5% loss of activity after 8 weeks and 60% loss after 10 weeks), ability to determine analyte concentrations at picogram level (0.2 pg mL−1 -20 pg mL−1), low limit of detection (0.00813 pg mL− 1), reproducibility, reusability (12 times) and high sensitivity.Öğe A novel and mass-sensitive quartz tuning fork platform for glial fibrillary acidic protein determination(Elsevier, 2025) Özcan, Burcu; Uludağ, İnci; Ünal, Mehmet Altay; Arı, Fikret; Sezgintürk, Mustafa Kemal; Özkan, Sibel A.Traumatic brain injury (TBI) is a major cause of mortality and disability worldwide, and its diagnosis is still difficult. A unique blood biomarker for numerous neurological disorders, including traumatic brain injury, is glial fibrillary acidic protein (GFAP). Portable, quick, and functional equipments are crucial in fighting against neurological illnesses. Quartz Tuning Fork (QTF) biosensors are attracting great attention due to their seamless integration with miniaturized and portable devices. This study introduces a new, adaptable, affordable frequency analyzer for GFAP detection. A simple and stable process to design a QTF system which has gold surface modified with 3-mercaptopropionic acid (3-MPA) and its biocompatibility with GFAP antigen was investigated. The surface morphology of the QTF system was analyzed during its immobilization procedure using Atomic Force Microscopy (AFM). The constructed QTF sensor system demonstrated high repeatability (the standard deviation: +/- 0.12183 Hz), good reproducibility, linearity, ability to detect antigen concentrations at femtogram levels. It proved that the QTF sensor system decorated with 3-MPA could be a good choice for the sensitive determination of GFAP, according to the statistical data. The modified QTF sensor demonstrated remarkably straightforward and mass-sensitive GFAP detection. The developed QTF-based biosensor achieved an outstanding linear detection range of 1-100 fg mL-1. The responses of the designed QTF-based sensor to commercial human serum also show that it is a successful and promising system for clinical use.Öğe A Practical and Single-Use ITO-Pet Based Immunosensing Platform for Detection of Tumor Necrosis Factor-Alpha Biomarker(Hacettepe University, 2023) Özcan, BurcuThis investigation displays a novel, practical indium tin oxide- polyethylene terephthalate (ITO-PET) based electrochemical biosensor for the Tumor Necrosis Factor-alpha (TNFα) biomarker determination. The ITO-PET electrode is a very advantageous preferred semiconductive electrode material. It has a lot of great features such as easy to prepare, cheapness, flexibility, stability. It also allows determining an analyte at very low concentrations and provides a great wide concentration range for analyte analysis. Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV) were used for the evaluation of biosensors, including the immobilization procedure, the investigation of the optimum conditions, and the characterization of biosensors. The immunosensor's electrode surface morphology during the immobilization process was observed using a Scanning Electron Microscope (SEM). In addition, Impedance measurement at a single frequency was used to characterize anti-TNFα and TNFα interactions (SFI). The clinical effectiveness of the developed biosensor was investigated by testing it with real human serum samples. Moreover, the fabricated immunosensor presents long shelf life, analysis of the antigen concentrations at picogram level (0.02 pg mL-1 -2.56 pg mL-1), reproducibility, reusability (11 times) and high sensitivity.Öğe An innovative and mass-sensitive quartz tuning fork (QTF) biosensor for GFAP detection: A novel approach for traumatic brain injury diagnosis(Elsevier Ltd, 2025) Özcan, Burcu; Uludağ Anıl, İnci; Ünal, Mehmet Altay; Arı, Fikret; Sezgintürk, Mustafa Kemal; Özkan, Sibel AyşılThe early diagnosis and management of traumatic brain injury (TBI) are dependent upon the early and precise detection of glial fibrillary acidic protein (GFAP). In this investigation, a novel biosensor based on quartz tuning forks (QTF) was introduced and functionalized with 11-mercaptoundecanoic acid (11-MUA). This biosensor is designed to facilitate the highly sensitive and selective detection of GFAP in human serum. In contrast to conventional neuroimaging methods, which are resource-intensive and frequently inaccessible in emergency situations, this innovative biosensor offers a portable, cost-effective, and efficient alternative for rapid GFAP measurement. The detection range of the system is 0.05 fg mL−1 to 25 fg mL−1. The Atomic Force Microscopy (AFM) was utilized to visualize the morphology of the QTF surface during the immobilization steps of the sensor. The developed biosensor presented advantages such as ability to determine GFAP concentrations at femtogram level, reproducibility and repeatability (standard deviation: ±0.0935966 Hz, and coefficient of variation: 7.91 %). This study highlights a significant progression in biosensing technology, providing an exceptionally sensitive and scalable platform for diagnosing neurological disorders, with potential uses in point-of-care environments. © 2025 The AuthorsÖğe Conclusion and future prospects(Elsevier, 2025) Uludağ Anıl, İnci; Özcan, Burcu; Özyurt, Canan; Demirbakan, Burçak; Kemal Sezgintürk, Mustafa KemalLateral flow assays (LFAs) are regarded as a significant technique because of their extensive variety of applications. As discussed in this chapter, they are used in a variety of areas, including clinical diagnostics, environmental surveillance, food safety, hormone balance assessment, cancer biomarker identification, and toxin analysis. Although these tests are renowned for their ability to deliver quick and uncomplicated outcomes, they do have several drawbacks, including limited sensitivity and the need for multiple testing. Advancements in technology have provided substantial breakthroughs to address the constraints of LFAs. Recent advancements in nanoparticles, particularly gold nanoparticles, quantum dots, and magnetic nanoparticles, have greatly enhanced the ability to amplify signals and identify many targets. These nanoparticles enhance the sensitivity of LFAs, facilitating the identification of targets even at low concentrations. Furthermore, LFAs that utilize aptamers have the added benefits of increased stability and reduced costs as compared to systems that rely on antibodies. Aptamers can be readily customized with diverse functional groups, offering versatility in experimental design and optimization. Furthermore, the incorporation of surface-enhanced Raman spectroscopy technology enhances the sensitivity of LFAs, allowing for the detection of substances even at lower concentrations. Consequently, the advancement of technology has enhanced the sensitivity and enhanced the user-friendliness of these tests. © 2026 Elsevier Inc. All rights reserved..Öğe Highly Sensitive and Single-Use Biosensing System Based on a GP Electrode for Analysis of Adiponectin, an Obesity Biomarker(Amer Chemical Soc, 2021) Özcan, Burcu; Sezgintürk, Mustafa KemalThis study presents a disposable, novel, and sensitive biosensing system to determine adiponectin, an obesity biomarker, in real human serum. The graphite paper (GP) working electrode is a new material for impedimetric biosensors. In the literature, there is no study in which this electrode is used in impedance-based biosensors for adiponectin detection. Sensitive and useful techniques, such as electrochemical impedance spectroscopy and cyclic voltammetry, were utilized for investigation of the modification of the GP electrode surface and optimization and characterization of the constructed biosensor. The single frequency impedance technique was used to study the interactions between antiadiponectin and adiponectin. The morphology of the electrode surface for each immobilization step was examined with scanning electron microscopy. All experimental parameters were optimized to fabricate a rapid and sensitive biosensing system. The designed biosensor presents excellent performance with a wide detection range (0.05-25 pg mL-1) and a low limit of detection (0.0033 pg mL-1) for adiponectin determination. Also, it has been demonstrated that the biosensor sensitively allows for the detection of adiponectin in human serum. The affinity of the designed immunosensor toward other proteins and components was examined in the presence of the target protein (adiponectin), leptin (100 pg mL-1), creatine kinase (50 pg mL-1), parathyroid hormone (50 pg mL-1), and d-glucose (0.5 M). The selectivity of the adiponectin biosensor resulted in high capacity to neglect the interference effect. The constructed biosensor showed good linearity, long-Term storage life (10 weeks), high reusability (18 times regenerability), and high ability to detect adiponectin concentrations at picogram levels. ©Öğe Lateral flow assays for food analyses: Food contaminants, allergens, toxins, and beyond(Elsevier Sci Ltd, 2023) İnce, Bahar; Uludağ, İnci; Demirbakan, Burçak; Özyurt, Canan; Özcan, Burcu; Sezgintürk, Mustafa KemalFood safety is a major issue because of the prevalence of pathogens, chemicals, and other potentially harmful substances in food products. Because of this, the creation of a reliable and accessible tool for checking on food quality is essential. In comparison to traditional techniques, lateral flow tests for the identification of food-borne pathogens are more modern, straightforward, and quick. This review examines the use of lateral flow biosensors for the detection of various food contaminants and the labels used to improve the effectiveness of the system. Since LFAs may be carried out by non-specialists, they are well-suited for on-site testing in a variety of food production and distribution environments.Öğe Lateral flow assays using aptamers(Elsevier, 2025) Özyurt, Canan; Demirbakan, Burçak; Özcan, Burcu; Uludağ Anıl, İnci; Kemal Sezgintürk, Mustafa Kemal; Ozkan, Sibel A.Aptamers, which are short single-stranded nucleic acids or peptides, have become versatile recognition elements as a result of their high specificity, stability, and cost-effectiveness. This chapter offers a thorough examination of aptamer-based lateral flow assays (LFA), with a particular emphasis on their principles, design strategies, and implications for environmental monitoring, food safety, and medical diagnostics. Aptamer-based systems provide superior chemical stability, an extended shelf life, and the ability to undergo a variety of modifications, in contrast to traditional antibody-based LFAs. This chapter also emphasizes the most recent developments in hybrid approaches that integrate aptamers with other biorecognition elements, signal amplification techniques, and aptamer selection methods. The novel concepts described in this chapter have the potential to facilitate the development of diagnostic instruments that are more cost-effective, portable, and efficient, and that have a broad range of applications in biosensor technology. © 2026 Elsevier Inc. All rights reserved..
