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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 novel electrochemical approach to biosensing applications: Quartz tuning forks as working electrodes for immunosensors(Elsevier, 2023) Arı, Fikret; İnce, Bahar; Ünal, Mehmet Altay; Sezgintürk, Mustafa Kemal; Özkan, Sibel A.Although cutting-edge technology has improved our understanding of many cancers, the diagnostic and treatment options available still need to be improved. Electrochemical biosensors play a key role as the most suitable platform used for this purpose. Quartz tuning forks (QTF) sensors have recently become the most valuable components for frequency measurements, with high stability, sensitivity, and low power consumption. No paper has previously been reported on the functionalization and isolation of QTF for biomarker determination using electrochemical methods, marking this research as unique for being the first to investigate the response and sensitivity of QTFs in these applications. Cardiac troponin T (cTnT), an important biomarker of cardiovascular disease, a four-step surface modification was performed to the prepared QTFs’ prongs. The surface was investigated in detail utilizing cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The results showed that the QTF-based immunosensor's limit of quantitation (LOQ) was 0.81 fg/mL, and the limit of detection (LOD) was 0.24 fg/mL, with a detection range of 0.5–1500 fg/mL. The results confirmed that QTFs have unique electrode capacity in point-of-care diagnostic devices. Most importantly, due to their excellent sensitivity and low cost, QTF transducers are predicted to be widely used as a unique electrode to detect many biomarkers in EIS and CV-based electrochemical biosensors.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 An innovative method for the detection of alpha synuclein, a potential biomarker of Parkinson's disease: quartz tuning fork-based mass sensitive immunosensor design(Royal Society of Chemistry, 2024) Sonuç Karaboğa, Münteha Nur; Ünal, Mehmet Altay; Arı, Fikret; Sezgintürk, Mustafa Kemal; Özkan, Sibel AyşılAn innovative biosensing fabrication strategy has been demonstrated for the first time using a quartz tuning fork (QTF) to develop a practical immunosensor for sensitive, selective and practical analysis of alpha synuclein protein (SYN alpha), a potential biomarker of Parkinson's disease. Functionalization of gold-coated QTFs was carried out in 2 steps by forming a self-assembled monolayer with 4-aminothiophenol (4-ATP) and conjugation of gold nanoparticles (AuNPs). The selective determination range for SYN alpha of the developed biosensor system is 1–500 ng mL−1 in accordance with the resonance frequency shifts associated with a limit of detection of 0.098 ng mL−1. The changes in surface morphology and elemental composition were evaluated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDX). The remarkable point of the study is that this QTF based mass sensitive biosensor system can capture the SYN alpha target protein in cerebrospinal fluid (CSF) samples with recoveries ranging from 92% to 104%.Öğe Development of ultra-sensitive and selective molecularly imprinted polymer-based electrochemical sensor for L-lactate detection(Elsevier, 2024) Pişkin, Ensar; Çetinkaya, Ahmet; Eryaman, Zulal; Karadurmuş, Leyla; Ünal, Mehmet Altay; Sezgintürk, Mustafa Kemal; Hizal, JulideLactate detection is important for the food and healthcare industries, and it's especially important when there's tissue hypoxia, hepatic illness, bleeding, respiratory failure, or sepsis. A new molecularly imprinted polymer (MIP) based electrochemical sensor was fabricated for differential pulse voltammetric assay of L-lactate (LAC). By using ZIF-8@ZnQ nanoparticles, the number of regions and effective surface area were increased. The polymeric film was obtained using 4 aminobenzoic acid (4-ABA) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a cross-linker, 2-hydroxyethyl methacrylate (HEMA) as basic monomers, and 2-hydroxy-2-methylpropiophenone one as initiator. The developed 4-ABA/LAC/ZIF-8@ZnQ@MIP-GCE was morphologically characterised using SEM and electrochemically using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements. A linear range of 0.1-1.0 pM LAC with a detection limit of 29.9 fM was found. Lastly, the MIP-based electrochemical sensor detected LAC in commercial human serum samples.Öğe Quartz tuning fork biosensor: A potential tool for SARS-CoV-2 detection(Elsevier, 2023) Kavacık, Mehmet; İnce, Bahar; Arı, Fikret; Ünal, Mehmet Altay; Sezgintürk, Mustafa Kemal; Özkan, Sibel A.Portable, fast, and practical devices are important in the fight against epidemic diseases. The lack of readily available small-scale commercial solutions prompted us to delve deeper into this research effort. Investment in Quartz Tuning Fork (QTF)-based biosensor research is significant due to its seamless integration with miniaturised and portable devices. Within the scope of this study, a new, cost-effective, and versatile frequency analyser designed for detecting diseases, compatible with screens of different sizes, has been introduced. The modified QTF sensor occured mass-sensitive SARS-CoV-2 nucleocapsid protein (SARS-NP) detection with remarkable simplicity, sensitivity, and selectivity. The developed QTF-based biosensor has an impressive linear detection range ranging from 5 to 200 ng/mL and an exceptionally low limit of detection (LOD) value of 1.72 ng/ mL. The sensitivity of the developed QTF-based biosensor was obtained as 50 Hz/1 mu M. The biosensor response was then evaluated in commercial human serum sample. After 15 days of storage, these biosensors retained approximately 93.7 % of their initial activity. Additionally, a Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) comprehensively characterised the electrode surface.Öğe The Evaluation of Clinical Applications for the Detection of the Alzheimer's Disease Biomarker GFAP(Taylor & Francis Inc, 2024) Özçelikay-Akyıldız, Göksu; Karadurmuş, Leyla; Çetinkaya, Ahmet; Uludağ, İnci; Ozcan, Burcu; Ünal, Mehmet Altay; Sezgintürk, Mustafa KemalOne of the most prevalent neurodegenerative diseases is Alzheimer's disease (AD). The hallmarks of AD include the accumulation of amyloid plaques and neurofibrillary tangles, which cause related secondary diseases, progressive neurodegeneration, and ultimately death. The most prevalent cell type in the human central nervous system, astrocytes, are crucial for controlling neuronal function. Glial fibrillary acidic protein (GFAP) is released from tissue into the bloodstream due to astrocyte breakdown in neurological diseases. Increased levels of GFAP in the serum can function as blood markers and be an effective prognostic indicator to help diagnose neurological conditions early on, from stroke to neurodegenerative diseases. The human central nervous system (CNS) is greatly affected by diseases associated with blood GFAP levels. These include multiple sclerosis, intracerebral hemorrhage, glioblastoma multiforme, traumatic brain injuries, and neuromyelitis optica. GFAP demonstrates a strong diagnostic capacity for projecting outcomes following an injury. Furthermore, the increased ability to identify GFAP protein fragments helps facilitate treatment, as it allows continuous screening of CNS injuries and early identification of potential recurrences. GFAP has recently gained attention due to data showing that the plasma biomarker is effective in identifying AD pathology. AD accounts for 60-70% of the approximately 50 million people with dementia worldwide. It is critical to develop molecular markers for AD, whose number is expected to increase to about 3 times and affect humans by 2050, and to investigate possible targets to confirm their effectiveness in the early diagnosis of AD. In addition, most diagnostic methods currently used are image-based and do not detect early disease, i.e. before symptoms appear; thus, treatment options and outcomes are limited. Therefore, recently developed methods such as point-of-care (POC), on-site applications, and enzyme-linked immunosorbent assay-polymerase chain reaction (ELISA-PCR) that provide both faster and more accurate results are gaining importance. This systematic review summarizes published studies with different approaches such as immunosensor, lateral flow, POC, ELISA-PCR, and molecularly imprinted polymer using GFAP, a potential blood biomarker to detect neurological disorders. Here, we also provide an overview of current approaches, analysis methods, and different future detection strategies for GFAP, the most popular biosensing field.
