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Öğe A disposable immunosensor using ITO based electrode modified by a star-shaped polymer for analysis of tumor suppressor protein p53 in human serum(Elsevier Advanced Technology, 2018) Aydin, Muhammet; Aydin, Elif Burcu; Sezgintürk, Mustafa KemalLabel-free immunosensor based on tetra armed star-shaped poly(glycidylmethacrylate) (Star(PGMA)) modified disposable ITO electrode was developed for detection of p53 protein, an important colorectal cancer biomarker. This disposable biosensor was fabricated by spin-coating technique using star-shaped Star(PGMA) with epoxy side groups. After formation of a stable film with epoxy ends, anti-p53 antibodies were bound to these groups covalently. Stepwise modification of the electrode was followed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) studies. The electrochemical performance of the immunosensor was studied by EIS. Furthermore, the antibody and antigen coupling was monitored by single frequency impedance (SFI) technique. The immunosensor showed a low limit of detection (7 fg/mL) and a linear detection range between 0.02 pg/mL and 4 pg/mL. Additionally, atomic force microscopy (AFM) and scanning electron microscopy (SEM) were utilized for monitoring of immunosensor surface at different stages of fabrication. The antibody coupling on the electrode surface was proved by Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. Furthermore, the proposed immunosensor had good reproducibility and repeatability.Öğe A highly selective electrochemical immunosensor based on conductive carbon black and star PGMA polymer composite material for IL-8 biomarker detection in human serum and saliva(Elsevier Advanced Technology, 2018) Aydin, Muhammet; Aydin, Elif Burcu; Sezgintürk, Mustafa KemalA new approach to enhance the electrochemical performance of biosensor was attempted by using Super P (c) carbon black/Star polymer composite material. In this study, we developed an electrochemical IL 8 biosensor by modification with a conductive composite including Super P, polyvinylidene fluoride (PVDF) and star polymer (SPGMA) of disposable ITO electrode surface. The Super P carbon black as carbonaceous material had a high conductivity and was used for the enhancement of electron transfer between electrode surface and electrolyte. Anti-IL 8 antibodies were utilized as biorecognition molecules and bound to epoxy groups of star polymer covalently. The chemical characterization of antibody immobilization on this composite was performed by using Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. The characterizations of stepwise modification of this immunosensor were performed by electrochemical techniques such as Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV) and Single Frequency Impedance (SFI); and morphological techniques such as Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Several variables that affect the immunosensor performance were optimized. Under optimum conditions, a wide linear range 0.01-3 pg/mL and low detection limit 3.3 fg/mL were obtained. Super P-star polymer composite modified immunosensor was easy, sensitive, cheap and reliable analytical method for IL 8 detection. The applicability of the proposed immunosensor to determine IL 8 in saliva and serum samples were examined. The results of biosensor and Enzyme-linked Immunosorbent Assay (ELISA) kit were in compatible. Consequently, it was concluded that the electrochemical immunosensor offers a potential approach for IL 8 detection in clinical applications.Öğe A Highly Selective Poly(thiophene)-graft-Poly(methacrylamide) Polymer Modified ITO Electrode for Neuron Specific Enolase Detection in Human Serum(Wiley-V C H Verlag Gmbh, 2019) Aydin, Muhammet; Aydin, Elif Burcu; Sezgintürk, Mustafa KemalIn this study, an impedimetric immunosensor based on polymer poly(thiophene)-graft-poly(methacrylamide) polymer (P(Thi-g-MAm)) modified indium tin oxide (ITO) electrode is developed for the detection of the Neuron Specific Enolase (NSE) cancer biomarker. First, the P(Thi-g-MAm) polymer is synthesized and coated on the ITO electrode by using a spin-coating technique. P(Thi-g-MAm) polymer acts as an immobilization platform for immobilization of NSE-specific monoclonal antibodies. Anti-NSE antibodies are utilized as biosensing molecules and they bind to the amino groups of P(Thi-g-Mam) polymer via glutaraldehyde cross-linking. Spin-coating technique is employed for bioelectrode fabrication and this technique provides a thin and uniform film on the ITO electrode surface. This bioelectrode fabrication technique is simple and it generates a suitable platform for large-scale loadings of anti-NSE antibodies. This immunosensor exhibits a wide linear detection range from 0.02 to 4 pg mL(-1) and with an ultralow detection limit of 6.1 fg mL(-1). It reveals a good long-term stability (after 8 weeks, 78% of its initial activity), an excellent reproducibility (1.29% of relative standard deviation (RSD)), a good repeatability (5.55% of RSD), and a high selectivity. In addition, the developed immunosensor is proposed as a robust diagnostic tool for the clinical detection of NSE and other cancer biomarkers.Öğe A highly sensitive immunosensor based on ITO thin films covered by a new semi-conductive conjugated polymer for the determination of TNF? in human saliva and serum samples(Elsevier Advanced Technology, 2017) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalA novel, ultrasensitive impedimetric immunosensor was constructed for the detection of tumor necrosis factor alpha (TNF alpha) by using Poly(3-thiophene acetic acid) (P3), a conjugated polymer as an immobilization matrix. The polymer P3 contains a lot of carboxylic acid groups on its surface that provide a larger biorecognition surface. This developed immunosensor was prepared on hydroxy-bearing ITO surface via an ester bond linkage of polymer P3 to immobilize anti-TNF alpha antibodies. The ITO electrode modification steps and interaction between anti-TNF alpha antibody and TNF alpha antigen were monitored by cyclic voltammetry (CV) and by electrochemical impedance spectroscopy (EIS) method. After the analytical parameters optimization, a linear detection response from 0.01 pg/mL to 2 pg/mL, a limit of detection LOD of 3.7 fg/mL and a limit of quantification (LOQ) of 12.4 fg/mL were achieved, which provided accurate results (relative standard deviation; 4.03%). The characterization of this developed immunosensor was performed by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), SEM-energy dispersive X-ray (EDX) mapping and atomic force microscopy (AFM). The immunosensor allowed a simple and fast detection of TNF alpha antigen in human serum and satisfied recoveries (98.69-105.20%) were obtained by using standard addition method.Öğe A label-free immunosensor for sensitive detection of RACK 1 cancer biomarker based on conjugated polymer modified ITO electrode(Elsevier, 2020) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalA new flexible biosensor based on conjugated polymer functionalized indium tin oxide (ITO) sheet was fabricated for Receptor for Activated C Kinase 1 (RACK 1) determination. Poly(3-thiophene acetic acid) (P(Thi-Ac)) was used as an immobilization matrix for construction of RACK 1 immunosensor. This polymer had a great number of carboxyl groups on its end site and these carboxyl ends provided anchoring points to the anti-RACK 1 antibodies. Anti-RACK 1 antibodies were covalently attached on the ITO electrode and recognized the RACK 1 antigens. Electrochemical characterizations were made by employing electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. Additionally, single frequency impedance method (SFI) was applied to follow the specific biointeraction between antibody and antigen. As a result of specific biointeraction, the designed immunosensor exhibited a wide linear detection range between 0.01 pg/mL and 2 pg/mL RACK 1 with a detection limit of 3.1 fg/mL. Scanning electron microscopy and atomic force microscopy analyses were employed for electrode surface morphology investigation. The designed RACK 1 biosensor had good repeatability (5.73 %, RSD), excellent reproducibility (2.5 %, RSD), long storage-stability and reusable property. In addition, the fabricated RACK 1 biosensor was applied to determine RACK 1 concentration in human serums and the recovery was ranging from 98.79%-100.22%. This work illustrated a new tool to construct a sensitive and low-cost disposable biosensor for applications in clinical monitoring. (C) 2020 Elsevier B.V. All rights reserved.Öğe Advances in electrochemical immunosensors(Elsevier Academic Press Inc, 2019) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalImmunosensors are compact tools on which antibody and antigen interactions are formed. The specific interaction between antibody and antigen is detected by using a transducer and an electrical signal is measured. This specific interaction between these molecules makes immunosensor very attractive for several applications in different fields. Electrochemical immunosensors are successful devices in selective and sensitive detection of several analytes. Electrochemical transducing methods such as voltammetric, potentiometric, conductometric or impedimetric have been utilized in different applications due to their excellent properties such as being low-cost, sensitivity and simplicity. In this chapter, the fundamentals of electrochemical immunosensors are summarized and different applications in food, environmental and clinical analyses are investigated and discussed.Öğe Biosensors and the evaluation of food contaminant biosensors in terms of their performance criteria(Taylor & Francis Ltd, 2020) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalBiosensor technology has been extensively investigated for determination of several analytes in clinical diagnosis, food analysis and environmental monitoring. A biosensor includes three parts; a transducer, a bioreceptor (biorecognition element) and a signal processing system. Biorecognition elements are important components of a biosensor because they recognise the target analytes of interest. To obtain a sensitive and a reproducible biosensor, nanomaterials are used as modification elements of transducer. They represent important promise as biorecognition element immobilisation platforms for the biosensor fabrication. This mini review summarises the biosensor? features, the factors affect its performance and nanomaterials, which are used as modification elements in food analysis area. After a brief description of the biosensors and nanomaterials, the developed biosensors in literature were investigated by means of tables. Linear ranges, LODs, reproducibilities, stabilities of developed biosensors are compared.Öğe Biosensors in Drug Discovery and Drug Analysis(Bentham Science Publ Ltd, 2019) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalBackground: The determination of drugs in pharmaceutical formulations and human biologic fluids is important for pharmaceutical and medical sciences. Successful analysis requires low sensitivity, high selectivity and minimum interference effects. Current analytical methods can detect drugs at very low levels but these methods require long sample preparation steps, extraction prior to analysis, highly trained technical staff and high-cost instruments. Biosensors offer several advantages such as short analysis time, high sensitivity, real-time analysis, low-cost instruments, and short pretreatment steps over traditional techniques. Biosensors allow quantification not only of the active component in pharmaceutical formulations, but also the degradation products and metabolites in biological fluids. The present review gives comprehensive information on the application of biosensors for drug discovery and analysis. Moreover, this review focuses on the fabrication of these biosensors. Methods: Biosensors can be classified as the utilized bioreceptor and the signal transduction mechanism. The classification based on signal transductions includes electrochemical optical, thermal or acoustic. Electrochemical and optic transducers are mostly utilized transducers used for drug analysis. There are many biological recognition elements, such as enzymes, antibodies, cells that have been used in fabricating of biosensors. Aptamers and antibodies are the most widely used recognition elements for the screening of the drugs. Electrochemical sensors and biosensors have several advantages such as low detection limits, a wide linear response range, good stability and reproducibility. Optical biosensors have several advantages such as direct, real-time and label-free detection of many biological and chemical substances, high specificity, sensitivity, small size and low cost. Modified electrodes enhance sensitivity of the electrodes to develop a new biosensor with desired features. Chemically modified electrodes have gained attention in drug analysis owing to low background current, wide potential window range, simple surface renewal, low detection limit and low cost. Modified electrodes produced by modifying of a solid surface electrode via different materials (carbonaceous materials, metal nanoparticles, polymer, biomolecules) immobilization. Recent advances in nanotechnology offer opportunities to design and construct biosensors. Unique features of nanomaterials provide many advantages in the fabrication of biosensors. Nanomaterials have controllable chemical structures, large surface to volume ratios, functional groups on their surface. To develop protein-inorganic hybrid nanomaterials, four preparation methods have been used. These methods are immobilization, conjugation, crosslinking and self-assembly. In the present manuscript, applications of different biosensors, fabricated by using several materials, for drug analysis are reviewed. The biosensing strategies are investigated and discussed in detail. Results: Several analytical techniques such as chromatography, spectroscopy, radiometry, immunoassays and electrochemistry have been used for drug analysis and quantification. Methods based on chromatography require time-consuming procedure, long sample-preparation steps, expensive instruments and trained staff. Compared to chromatographic methods, immunoassays have simple protocols and lower cost. Electrochemical measurements have many advantages over traditional chemical analyses and give information about drug quantity, metabolic fate of drugs, and pharmacological activity. Moreover, the electroanalytical methods are useful to determine drugs sensitively and selectivity. Additionally, these methods decrease analysis cost and require low-cost instruments and simple sample pretreatment steps. Conclusion: In recent years, drug analyses are performed using traditional techniques. These techniques have a good detection limit, but they have some limitations such as long analysis time, expensive device and experienced personnel requirement. Increased demand for practical and low-cost analytical techniques biosensor has gained interest for drug determinations in medical sciences. Biosensors are unique and successful devices when compared to traditional techniques. For drug determination, different electrode modification materials and different biorecognition elements are used for biosensor construction. Several biosensor construction strategies have been developed to enhance the biosensor performance. With the considerable progress in electrode surface modification, promotes the selectivity of the biosensor, decreases the production cost and provides miniaturization. In the next years, advances in technology will provide low cost, sensitive, selective biosensors for drug analysis in drug formulations and biological samples.Öğe Comparative analysis of artificial neural networks and adaptive neuro-fuzzy inference system for biocomposite material synthesis and property prediction(Elsevier Science Sa, 2025) Aydin, Muhammet; Aydogmus, Ercan; Arslanoglu, HasanBiocomposite materials (BMs) are becoming increasingly prevalent in modern applications. Estimating their production values involves various techniques, depending on the proportions of materials used. Among these techniques, artificial neural networks (ANN), fuzzy logic, statistical methods, and the adaptive neural fuzzy inference system are prominent. In this study, polyester biocomposites have been synthesized experimentally by adjusting the quantities of methyl ethyl ketone peroxide (MEKP), cobalt octoate (Co Oc) metal catalyst, marble factory waste, modified castor oil (MCO), and polyester raw material (UP) in specific ratios. The testing and analysis of these materials are conducted to determine parameters such as bulk density (BD), thermal conductivity coefficient (TCC), and activation energy (Ea). Subsequently, input and output values of the BMs are obtained, and ANN and adaptive neuro-fuzzy inference system (ANFIS) methods are employed for assessment. Both networks are trained and modeled using experimental data to construct their respective architectures. Validation of the models has been performed using data separate from the training set. A comparison between the actual values and those predicted by the network architectures revealed that the ANN method yielded outcomes with an average error of 0.3849 %, outperforming ANFIS. The findings showed that while ANFIS produced superior predictions for the Ea output value, the ANN structure fared better in predicting output values the BD and TCC.Öğe Construction of succinimide group substituted polythiophene polymer functionalized sensing platform for ultrasensitive detection of KLK 4 cancer biomarker(Elsevier Science Sa, 2020) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalA novel impedimetric immunosensor based on conjugated succinimide group substituted polythiophene polymer (SucS-PThi) modified indium tin oxide (ITO) electrode was fabricated for ultra-sensitive and ultra-selective determination of kallikrein 4 (KLK 4) antigen in diluted human serum. The basic reason for the usage of SucS-PThi polymer was that its rich effective functional groups and biocompatibility. KLK 4, an important prostate biomarker was the target analyte and anti-KLK 4 antibodies immobilized electrode was the diagnostic tool for KLK 4 antigen detection. The fabricated biosensor was characterized by employing electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), fourier transform-infrared (FTIR) and Raman spectroscopy. Under optimized conditions, a linear concentration range from 0.04 pg/mL to 30 pg/mL and a low detection limit (LOD) of 12.2 fg/mL were obtained and the LOD was lower than of most of the existing techniques, illustrating its feasibility for practical application. Moreover, the developed sensing system combined the outstanding properties in terms of selectivity, sensitivity, repeatability, reproducibility and reusability, without requiring for labor - intensive labeling stages. In addition, it was successfully utilized for accurate quantification of KLK 4 antigen in human serum samples.Öğe Determination of calreticulin using Fe3O4@AuNPs core-shell functionalized with PT(COOH)2 polymer modified electrode: A new platform for the impedimetric biosensing of cancer biomarkers(Elsevier Science Sa, 2022) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalAn innovative biosensing design strategy was utilized for the first time to develop a label-free and practical immunosensor for ultrasensitive analysis of calreticulin (CRT), a potential biomarker of breast carcinoma. Unlike strategies used in literature, a conjugated polymer carrying carboxyl groups on its backbone was synthesized and utilized as an immobilization matrix. This immunosensor design strategy was composed of the attachment of anti-CRT antibodies onto iron oxide nanoparticles@gold nanoparticles@poly(3-thiophenemalonic acid) polymer (Fe3O4@AuNPs@PT(COOH)(2)) functionalized indium tin oxide (ITO) electrode through carbodiimide coupling reaction. EIS measurement results illustrated significant changes in charge transfer resistance (R-ct) on immunoreaction between anti-CRT and CRT proteins. The proposed immunosensor enabled the detection of CRT over the range of 0.02 pg/mL and 100 pg/mL with a correlation coefficient of 0.9994 under optimal conditions. The detection limit (LOD), the quantification limit (LOQ) and the sensitivity were also determined to be 8.2 fg/mL, 27.4 fg/mL and 270 k Omega fg mL(-1)cm(2), respectively. Furthermore, it also exhibited good repeatability, excellent reproducibility, long storage stability and reusability. Experimental results analyzed with T-test to compare the means of the repeatability and reproducibility data, and F-test to the distribution of the repeatability and reproducibility data. According to T and F-tests, the experimental results achieved from the studies with the suggested immunosensor were relatively satisfactory. Furthermore, this immunosensor was tested to measure CRT levels in human serum and spiked human serum samples, and acceptable recovery rates ranging from 94.05% to 106.62% were obtained. In sum, considering its fast and easy-to-fabricate properties, this new strategy offers a potential tool for CRT biomarker detection.Öğe Electrochemical bioplatform for the determination of the most common and carcinogenic dibutyl phthalate migrated from daily-use plastic products(Springer Wien, 2025) Aydin, Elif Burcu; Aydin, Muhammet; Sezginturk, Mustafa KemalDibutyl phthalate (DBP) is a typical plasticizer used in the production and processing of plastic items. Given that DBP is easily leached and discharged into the environment, posing a threat to nature and living things, a facile and feasible impedimetric magneto biosensor for ultrasensitive determination of DBP was constructed first of all by using epoxy-functionalized magnetic nanoparticles as a sensing platform. A magnetic field on the electrode surface kept the epoxy-functionalized magnetic nanoparticles in place, and the particular interaction was conducted on the solid platform of magnetic nanoparticles. This sensing platform with a large surface area enhanced to attach a large amount of DBP-specific aptamer leads to a further increase in the sensitivity of the aptasensor. The DBP-specific aptamer was covalently attached to the epoxy groups of the 3-(glycidoxypropyl)trimethoxysilane (GPMS) agent standing at the magnetic nanoparticle surface without using any crosslinking agent. Meanwhile, the DBP aptamer attached to the as-prepared epoxy-functionalized magnetic nanoparticles via amide bonds specifically recognized the DBP analyte. The interactions of DBP with the aptamer on the epoxy-functionalized magnetic nanoparticles were studied by different electrochemical techniques, and for the quantification of DBP, electrochemical impedance spectroscopy (EIS) was utilized. In the best conditions, the electrochemical aptasensor showed good results for measuring DBP, with a broad range from 1 to 200 pg/mL and a very low detection limit (LOD) of 0.32 pg/mL. Importantly, the resulting aptasensor had excellent repeatability and reproducibility, desirable specificity, long storage stability, and high sensitivity, indicating its potential applications in food and environmental safety. In addition, the real sample experiments performed on the daily-use plastic products revealed the feasibility of the proposed detection approach.Öğe Electrochemical immunosensor based on chitosan/conductive carbon black composite modified disposable ITO electrode: An analytical platform for p53 detection(Elsevier Advanced Technology, 2018) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalIn this study, we fabricated a label-free electrochemical immunosensor for sensitive and selective detection of tumor marker p53. This immunosensor was based on chitosan/carbon black composite (Chitosan-CB) layer coated ITO electrode. This composite was utilized for enhancement of the conductivity of the immunosensor. Anti-p53 antibodies were captured on the modified ITO electrode through the cross-linking of chitosan and glutaraldehyde. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques were utilized for electrochemical characterization of the proposed immunosensor. Moreover, the biosensor construction steps were monitored by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The immobilization of anti-p53 antibodies on the electrode surface was investigated by using Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The change in impedance which formed during the specific interaction between anti-p53 antibody and p53 antigen was used to detect p53. Under optimized experimental conditions, the fabricated immunosensor had a wide linear range of 0.01-2 pg/mL and low detection limit of 3 fg/mL. The fabricated immunosensor had good sensitivity, stability and repeatability. Furthermore, it was successfully applied to analyze p53 in human serum.Öğe Electrochemical immunosensor for CDH22 biomarker based on benzaldehyde substituted poly(phosphazene) modified disposable ITO electrode: A new fabrication strategy for biosensors(Elsevier Advanced Technology, 2019) Aydin, Muhammet; Aydin, Elif Burcu; Sezgintürk, Mustafa KemalA novel label-free impedimetric immunosensor was fabricated for rapid, selective and sensitive detection and quantification of Cadherin-like protein 22 (CDH22), a cancer marker, in human serum by using easy and quickly prepared disposable ITO immunoelectrode. cancer marker, in human serum by using easy and quickly prepared disposable ITO immunoelectrode. The biosensing approach implied the use of ITO electrode coated with poly (phosphazene) polymer including benzaldehyde groups attached with CDH22 antibody and CDH22 antigens. Benzaldehyde side groups containing poly(phosphazene) film coated disposable ITO electrode were utilized as an immunosensing platform and anti-CDH22 antibodies bound to aldehyde groups of benzaldehyde substituted poly(phosphazene) (P-PHP) covalently. The immunosensor modification steps and affinity interaction between anti-CDH22 antibodies and CDH22 antigens were observed by EIS and CV in the presence of the redox couple. Furthermore, antibody immobilization was followed via FTIR and Raman spectroscopy. The morphological analyses of the suggested immunosensor during the fabrication steps were carried out with SEM and AFM monitoring. All the experimental parameters affecting the construction of the immunoelectrodes were optimized. The fabricated immunosensor exhibited an excellent working performance with a wide detection linear range (0.015-2.9 pg/mL) and low limit of detection (4.4 fg/mL). Moreover, the proposed immunosensor had great reproducibility, repeatability and long-term stability. Additionally, the fabricated immunosensor was successfully used in the quantification of CDH22 in human serum without any pretreatment.Öğe Highly sensitive electrochemical immunosensor based on polythiophene polymer with densely populated carboxyl groups as immobilization matrix for detection of interleukin 1? in human serum and saliva(Elsevier Science Sa, 2018) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalA new impedimetric immunosensor was fabricated for detection of Interleukin 1 beta (IL-1 beta) by using semi-conductive poly(2-thiophen-3-yl-malonic acid) (P3-TMA) as an immobilization matrix material and anti-IL-1 beta antibody as a biorecognition element for the first time. The polymer P3-TMA bound onto hydroxylated ITO surface via ester bond to form a polymer interface including active carboxyl groups. These reactive carboxyl groups bound to anti-IL-1 beta antibodies via amide bond under coupling reagent of N-beta-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide. The detection of IL-1 beta antigen was monitored with electrochemical impedance spectroscopy technique (EIS). Apart from EIS technique, cyclic voltammetry (CV), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), SEM-energy dispersive X-ray (EDX) mapping, atomic force microscopy (AFM) were used for characterization of immunosensor. The effect of antibody and antigen incubation durations, and utilized biorecognition element concentrations were investigated to determine the optimum analytical performance of the immunosensor. Under optimized conditions, the relative change in impedance was proportional to the IL-1 beta concentration in the range of 0.01-3 pg/mL with the detection limit 3 fg/mL. The proposed immunosensor had good specificity, reproducibility and stability. The immunosensor was applicable for detection of IL-1 beta in human serum and saliva samples with satisfied recoveries (97.4-104.5%). (C) 2018 Elsevier B.V. All rights reserved.Öğe Immobilization Techniques of Nanomaterials(Academic Press Ltd-Elsevier Science Ltd, 2019) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa Kemal[Anstract Not Available]Öğe Impedimetric Detection of Calreticulin by a Disposable Immunosensor Modified with a Single-Walled Carbon Nanotube-Conducting Polymer Nanocomposite(Amer Chemical Soc, 2022) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalA label-free impedimetric immunosensing system was constructed for ultrasensitive determination of the calreticulin (CALR) biological marker in human serum samples utilizing an electrochemical impedance spectroscopy analysis technique for the first time. The new biosensor fabrication procedure consisted of electro-deposition of single-walled carbon nanotubes (SWCNTs) incorporating polymerization of an oxiran-2-yl methyl 3-(1H-pyrrol-1-yl) propanoate monomer (Pepx) onto a low-cost and disposable indium tin oxide (ITO) electrode. The SWCNTs-PPepx nanocomposite layer was prepared onto the ITO after the one-step fabrication procedure. The fabrication procedure of the immunosensor and the characteristic biomolecular interactions between the anti-CALR and CALR were characterized by electrochemical analysis and morphological monitoring techniques. Under optimum conditions, the proposed biosensor was responsive to CALR concentrations over the detection ranges of 0.015-60 pg/mL linearly, and it had a very low detection limit (4.6 fg/mL) and a favorable sensitivity (0.43 k omega pg(-1) mL cm(-2)). The reliability of the biosensor system in clinical analysis was investigated by successful quantification of CALR levels in human serum. Moreover, the repeatability and reproducibility results of the biosensor were evaluated by using Dixon, Grubbs, T-test, and F-tests. Consequently, the proposed biosensor was a promising method for scientific, rapid, and successful analysis of CALR in human serum samples.Öğe Label-free and reagent-less electrochemical detection of nucleocapsid protein of SARS-CoV-2: an ultrasensitive and disposable biosensor(Royal Soc Chemistry, 2022) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalA novel selective and ultrasensitive sandwich biosensor was developed for the detection of nucleocapsid biomarkers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The biosensor fabrication strategy was composed of a combination of gold nanoparticles (AuNPs) electrodeposition and an aldehyde substituted thiophene monomer (3-Thi-Ald) electropolymerization. In this study, an effective surface design was achieved during biosensor fabrication by covalent immobilization of biorecognition elements. The Pthi-Ald polymer not only formed a surface immobilization matrix, but also supported the electrode surface conductivity with its conductive property. The immobilized antibodies on Pthi-Ald polymer could selectively capture nucleocapsid antigen via the specific immunoreaction that resulted in a blockage of the electron transfer through the working electrode because of the resistance of nucleocapsid protein. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and scanning electron microscopy (SEM) techniques were utilized to confirm the step-by-step fabrication procedure of the immunosensor. The developed immunosensor showed good selectivity, high storage stability, acceptable repeatability, and a good reproducibility for nucleocapsid detection. The AuNPs-Pthi-Ald polymer modified biosensor illustrated a good linear dynamic detection range between 0.0015 pg mL(-1) and 150 pg mL(-1) nucleocapsid concentration with a low detection limit of 0.48 fg mL(-1). Moreover, the immunosensor had excellent selectivity, stability, and performance in the analysis of artificial nasal secretion samples. This strategy provided a new aspect for the early screening of SARS-CoV-2 infection.Öğe Selective and ultrasensitive electrochemical immunosensing of NSE cancer biomarker in human serum using epoxy-substituted poly(pyrrole) polymer modified disposable ITO electrode(Elsevier Science Sa, 2020) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalAn ultrasensitive, specific and label-free immunosensor was developed to determine the lowest alteration of neuron specific enolase antigen (NSE), the standard biomarker of lung cancer patients. This immunosensor was the first biosensor which was fabricated by utilizing epoxy-substituted-polypyrrole P(Pyr-Epx) polymer as an immobilization platform. The fabrication steps of the immunosensor were followed by using electrochemical studies (electrochemical impedance spectroscopy and cyclic voltammetry) and these techniques were applied to characterize the binding interactions. Scanning electron microscopy and atomic force microscopy analyses were performed to investigate the changes formed on the indium fin oxide electrode surface morphology and electrode surface structure. The optimization of the experimental parameters and the analytical performance of the proposed immunosensor were widely evaluated. Under optimum experimental conditions, the change in impedimetric signal was determined to follow the specific biointeraction between anti-NSE antibody and NSE antigen. The sensing ability of the proposed immunosensor for NSE detection showed a wide linear detection range of 0.02-7.5 pg/mL, with a low detection limit of 6.1 fg/mL. This impedimetric immunosensor also demonstrated highly repeatable and reproducible responses, and reliable results in the analysis of human serum samples with recoveries between 98.29 % and 102.81 %. In addition, the designed immunosensor could be used for detection of lung cancer biomarkers after simple dilution of serum samples with phosphate buffer.Öğe The development of an ultra-sensitive electrochemical immunosensor using a PPyr-NHS functionalized disposable ITO sheet for the detection of interleukin 6 in real human serums(Royal Soc Chemistry, 2020) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa KemalA label-free impedimetric immunosensor based on a conjugated poly(pyrroleN-hydroxy succinimide) (PPyr-NHS) polymer covered disposable indium tin oxide electrode (ITO) was fabricated for the ultrasensitive determination of interleukin 6 (IL 6) antigen. In this sensing platform, the PPyr-NHS polymer, which carried a number of succinimide groups on its end side, was used as a matrix material for the first time. This synthesized polymer had excellent biocompatibility and good electrical conductivity. In addition, the utilization of this material as a matrix material provided direct immobilization of the IL 6 receptor (IL6R), which was employed as a biorecognition element. The preparation of the working electrode, the successful attachment of IL 6R and specific interaction between IL6R and IL 6 antigen were confirmed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. Moreover, the working electrode surface was characterized by Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy during its construction. An impedimetric method was employed for the quantification of IL 6 antigen. Under optimized experimental conditions, the designed sensing platform could detect IL 6 antigen with a wide detection range from 0.03 pg mL(-1)to 22.5 pg mL(-1)with a relatively low detection limit of 10.2 fg mL(-1). In addition, the developed biosensor had outstanding sensitivity and specificity, good repeatability and reproducibility, high stability and reusability. Additionally, the designed sensing tool was successfully used in human serum samples. Consequently, the suggested immunosensor was clinically useful in the early detection of prostate cancer by direct determination of the serum IL 6 antigen level after simple dilution.
