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A comparison between LP(GMA) and CLP(GMA) polymer composites as an immobilization matrix for biosensing applications: A model immunosensor for IL 1?
(Elsevier Science Bv, 2019) Aydin, Elif Burcu; Sezgintürk, Mustafa Kemal
A comparative study was made by using two matrices (Linear poly(glycidyl methacrylate) (GMA) polymer (LP(GMA)) and carbon black-polyvinylidene fluoride (PVDF)-LP(GMA) composite CLP(GMA)) as immobilization platforms for anti-IL 1 alpha antibody on the development of impedimetric immunosensor for IL 1 alpha biomarker determination. These materials were spin coated onto the clean ITO electrode surface separately and used for IL 1 alpha immunosensor fabrication. Carbon black is utilized as a conductive material and has been employed over the last few decades for electrochemical biosensors development. The using of CLP(GMA) composite as an interface material shows fast electron transfer, when compared to LP(GMA) modified ITO electrode. This comparative study investigated the efficacy of carbon black for impedimetric biosensing. Anti-IL 1 alpha antibodies were utilized as bioreceptors and bound to epoxy groups of GMA polymer. For electrochemical characterizations, Electrochemical Impedance Spectroscopy, Cyclic Voltammetry and Single Frequency Impedance methods were employed. Furthermore, to follow the antibody attachment on the modified ITO substrates, Fourier Transform Infrared Spectroscopy and Raman spectral techniques were utilized. The morphological characterizations of immunosensor construction stages were carried out by Scanning Electron Microscopy and Atomic Force Microscopy analyses. The sensitive and label-free technique of EIS was used for quantification of IL 1 alpha concentration. Under optimum experimental conditions, the immunosensor had a good linear relationship between impedance values and the IL 1 alpha concentrations ranging from 0.01 to 2 pg/mL and from 0.01 to 3 pg/mL for LP(GMA) and CLP(GMA) modified ITO electrodes, respectively. The results confirmed that CLP(GMA) used in the preparation of the immunosensor illustrated improvements in immunosensor performance, comparing to the LP(GMA) modified immunosensor. Additionally, the immunosensor was successfully applied to evaluate human serum and saliva samples. The obtained results from these samples illustrated the feasibility of the immunosensor for clinical diagnosis in complex biological samples. Also, a simple and low-cost approach was attempted for development of immunosensor with remarkable performance characteristics. (C) 2019 Elsevier B.V. All rights reserved.
A disposable and ultrasensitive ITO based biosensor modified by 6-phosphonohexanoic acid for electrochemical sensing of IL-1? in human serum and saliva
(Elsevier Science Bv, 2018) Aydin, Elif Burcu; Sezgintürk, Mustafa Kemal
In this study, we constructed a new and sensitive ITO based electrochemical immunosensor for detection of interleukin 1 beta(IL-1 beta), a cancer biomarker found in serum and saliva. 6-phosphonohexanoic acid (PHA) was used as a biomolecule immobilization matrix for the first time. Anti-IL-1 beta antibody was utilized as a biorecognition molecule that immobilized onto carboxyl groups of 6-phosphohexanoic acid (PHA) via amide bond. Selective interaction between anti-IL-1 beta antibodies and IL-1 beta antigens was investigated by Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV) and Single Frequency Impedance (SFI) methods. The surface characterization of the immunosensor was performed by fourier transform infrared spectroscopy (FTIR), raman spectroscopy, scanning electron microscopy (SEM), SEM-energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) in order to illustrate individual steps of biosensor construction. Under the optimized experimental conditions, the change in impedance was proportional to IL-1 beta concentrations in the range of 0.025-3 pg/mL (R-2 = 0.99) with detection limit of 7.5 fg/mL. The reproducibility, repeatability, stability, and specificity of the developed immunosensor were analyzed. In addition, the developed immunosensor was successfully utilized for the determination of IL-1 beta in serum and saliva samples by using the standard addition method with recoveries of 96.7-105.4%. This immunosensor was applicable for the requirements of routine analysis with respect to performance, functionality and cost. (C) 2018 Elsevier B.V. All rights reserved.
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 Kemal
Label-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.
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 Kemal
A 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.
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 Kemal
In 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.
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 Kemal
A 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.
A label-free electrochemical biosensor for direct detection of RACK 1 by using disposable, low-cost and reproducible ITO based electrode
(Elsevier Science Bv, 2018) Torer, Hakan; Aydin, Elif Burcu; Sezgintürk, Mustafa Kemal
In this study we designed an ultrasensitive electrochemical immunosensor for RACK 1 detection using 11-cyanoundecyltrimethoxysilane (11-CUTMS) as a immobilization matrix to immobilize biorecognition element. The used silane agent (11-CUTMS) provides a favorable platform for efficient loading of anti-RACK 1 antibody. The effective loading of the biorecognition element on the 11-CUTMS matrix was monitored by scanning electron microscopy (SEM), atomic force microscopy (AFM) images and fourier transform infrared spectroscopy (FTIR) spectra. The electrochemical characterization of the immunosensor was performed by using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. Moreover, biorecognition interaction between anti-RACK1 antibodies and RACK1 antigens was monitored by using single frequency technique (SFI). The operating conditions, calibration curves obtained during optimization of experiments and reproducibility of the proposed impedimetric RACK1 biosensor are also investigated and discussed. The electrochemical immunosensor illustrated a sensitive response to RACK 1 antigen with detection limit of 10.8 fg/mL and in the linear range of 0.036 -2.278 pg/mL (R-2 = 0.999). Owing to high specificity, good reproducibility, long stability and reusability, the fabricated immunosensor will provide a sensitive, selective approach to RACK 1 detection. Furthermore, the practical applicability in human serum samples were investigated with a satisfactory result. (C) 2018 Elsevier B.V. All rights reserved.
A label-free electrochemical biosensor for highly sensitive detection of GM2A based on gold nanoparticles/conducting amino-functionalized thiophene polymer layer
(Elsevier Science Sa, 2023) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa Kemal
In this study, a new immunosensor based on an indium tin oxide (ITO) substrate functionalized with gold nanoparticles (GNPs)/amino-functionalized thiophene polymer P(ThiAmn) multilayer was fabricated for impedimetric determination of GM2 activator protein (GM2A). To engineer the biosensor, a relatively simple approach composed of GNPs electrodeposition and ThiAmn electropolymerization was utilized. The use of GNPs and P(ThiAmn) increased the substrate surface area, which was beneficial to immobilize a large amount of antiGM2A biorecognition elements. The designed bifunctional layer served as a promising matrix material and provided an innovative sensor fabrication. Electrochemical techniques were employed to investigate the specific immuno-interaction process between biorecognition anti-GM2A antibodies and GM2A antigens. Apart from these techniques, spectral techniques were utilized for the characterization of different modified electrode surfaces. Under optimum conditions, GM2A was determined in a linear concentration range from 0.0185 to 111 pg/mL with a detection limit (LOD) of 5.8 fg/mL by electrochemical impedance spectroscopy (EIS) technique. This biosensor exhibited good reproducibility, long storage-stability, and excellent specificity for GM2A antigens. Additionally, this immunosensor was applied to quantify GM2A in commercial serum samples, and satisfactory results were obtained.
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 Kemal
A 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.
A novel electrochemical immunosensor based on ITO modified by carboxyl-ended silane agent for ultrasensitive detection of MAGE-1 in human serum
(Academic Press Inc Elsevier Science, 2017) Gundogdu, Ash; Aydin, Elif Burcu; Sezgintürk, Mustafa Kemal
A new, low-cost electrochemical immunosensor was developed for rapid detection of Melanoma associated antigen 1 (MAGE-1), a cancer biomarker. The fabrication procedure of immunosensor was based on the covalent immobilization of anti-MAGE-1, biorecognition molecule, on ITO electrode by carboxyethylsilanetriol (CTES) monolayer. The biosensing MAGE-1 antigen was monitored by using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) technique. Apart from these techniques, single frequency impedance (SFI) was used for investigation of antibody-antigen interactions. Scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) were utilized for characterization of the proposed biosensor. To fabricate highly sensitive, good stability immunosensor, some parameters were optimized. Under optimal conditions, the developed electrochemical immunosensor for MAGE-1 exhibited a dynamic range of 4 fg/mL and 200 fg/mL with a low detection limit of 130 fg/mL. It had acceptable repeatability (5.05%, n = 20) and good storage stability (3.58% loss after 10 weeks). Moreover, this electrochemical immunosensor has been successfully applied to the determination of MAGE-1 in human serum samples. (C) 2017 Elsevier Inc. All rights reserved.
A sensitive and disposable electrochemical immunosensor for detection of SOX2, a biomarker of cancer
(Elsevier Science Bv, 2017) Aydin, Elif Burcu; Sezgintürk, Mustafa Kemal
A novel, sensitive, disposable indium tin oxide (ITO)-based electrochemical immunosensor was developed firstly for simple, rapid determination of Sex-determining region Y-box 2 (SOX2). SOX2 is a cancer biomarker and used for detecting small cell lung cancer, lung adenocarcinoma, squamous cell carcinoma, skin cancer, prostate cancer, and breast cancer. In this study, a disposable ITO thin film based electrode was used as working electrode for biosensing the interaction between SOX2 antigen and anti-SOX2 antibody. In this study, carboxyethylsilanetriol (CTES) was also utilized for electrode modifying so as to obtain self-assembled monolayers. The formed self-assembled monolayers were activated with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS) chemistry and they were used as a heterobifunctional crosslinker and activator, respectively. Anti-SOX2 antibody was used as a biorecognition molecule and was covalently immobilized onto the ITO thin film modified with CTES. Immobilization steps were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The optimum immobilization conditions such as antibody concentration, antibody and antigen incubation times were examined for the best sensitivity of the immunosensor. Under optimal conditions, this immunosensor had a wide linear detection range (25 fg/mL-2 pg/mL) with a detection limit as low as 7 fg/mL SOX2. Furthermore, the developed SOX2 immunosensor had good storage stability (79.36% of initial activity after 9 weeks), repeatability (3.88% of RSD) and reproducibility (4.25% of RSD). Our developed immunosensor has an acceptable performance for detection of SOX2 antigen, exhibits low detection limit, and has selective and reproducible results in immunoreaction analysis.
Advances in electrochemical immunosensors
(Elsevier Academic Press Inc, 2019) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa Kemal
Immunosensors 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.
An epoxysilane modified indium tin oxide electrode for the determination of PAK 2: Application in human serum samples
(Elsevier Science Bv, 2019) Yilmaz, Nergiz; Aydin, Elif Burcu; Sezgintürk, Mustafa Kemal
In this study, a sensitive immunosensor was developed for the first time for p21-activated kinase 2 (PAK 2) detection. In the design of the immunosensor, 3-glycidoxypropyltrimethoxysilane (GPTMS) was utilized as an ITO electrode modification material for anti-PAK 2 antibody immobilization. This molecule had epoxy group, which was reactive to amino groups of antibodies. Anti-PAK 2 antibodies were also used as biomolecules for sensitive interaction for PAK 2 antigen. In the presence of PAK 2 antigens, high impedance signal was observed when the process followed by using Electrochemical Impedance Spectroscopy technique (EIS). Apart from EIS technique, Cyclic Voltammetry (CV), Square Wave Voltammetry (SWV) and Single Frequency Impedance (SFI) techniques were utilized. Microscopic surface characterizations of immunosensor fabrication steps were performed by using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The immunosensor exhibited good sensitivity and selectivity for PAK 2 antigen detection. A linear calibration curve between EIS response and PAK 2 concentration was obtained in the range of 0.005-0.075 pg/mL with the detection limit of 1.5 fg/mL. It had good repeatability, excellent reproducibility and high stability. Additionally, this immunosensor can be reused by simple application protocol. Furthermore, it had good recovery for PAK 2 antigen detection in human serum samples. The good recovery illustrated that the developed immunosensor was a promising tool for PAK 2 detection in practical applications. (C) 2019 Elsevier B.V. All rights reserved.
An impedimetric immunosensor for highly sensitive detection of IL-8 in human serum and saliva samples: A new surface modification method by 6-phosphonohexanoic acid for biosensing applications
(Academic Press Inc Elsevier Science, 2018) Aydin, Elif Burcu; Sezgintürk, Mustafa Kemal
In this study, we fabricated a sensitive and label-free impedimetric immunosensor based on 6-phosphonohexanoic acid (PHA) modified ITO electrode for detection of interleukin-8 (IL-8) in human serum and saliva. PHA was first employed to cancer biomarker sensing platform. Anti-IL-8 antibody was used as a biorecognition element and the detection principle of this immunosensor was based on monitoring specific interaction between anti-IL-8 antibody and IL-8 antigen. The morphological characterization of each electrode modification step was analyzed by scanning electron microscopy (SEM), SEM-energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) while electrochemical characterization was performed by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and single frequency impedance (SFI) techniques. Moreover, the antibody immobilization on the electrode surface was proved Fourier-transform infrared spectroscopy (FTIR) and Raman Spectroscopy. This proposed impedimetric immunosensor exhibited good performances with a wide linear in the range from 0.02 pg/mL to 3 pg/mL as well as a relative low detection limit of 6 fg/mL. The impedimetric immunosensor had a good specificity, stability and reproducibility. This study proved that PHA was a suitable interface material to fabricate an electrochemical biosensor.
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 Kemal
Biosensor 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.
Biosensors in Drug Discovery and Drug Analysis
(Bentham Science Publ Ltd, 2019) Aydin, Elif Burcu; Aydin, Muhammet; Sezgintürk, Mustafa Kemal
Background: 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.
Carboxyethylsilanetriol-Coated Magnetic Nanoparticles as an Ultrasensitive Immunoplatform for Electrochemical Magnetosensing of Cotinine
(Amer Chemical Soc, 2024) Aydin, Muhammet; Aydin, Elif Burcu; Sezgintürk, Mustafa Kemal
In the present study, an innovative and simple electrochemical magneto biosensor based on carboxyethylsilanetriol-modified iron oxide (Fe3O4) magnetic nanoparticles was designed for ultrasensitive and specific analysis of cotinine, an important marker of smoking. Anticotinine antibodies were covalently immobilized on carboxylic acid-modified magnetic nanoparticles, and the cotinine-specific magnetic nanoparticles created a specific surface on the working electrode surface. The use of magnetic nanoparticles as an immobilization platform for antibodies provided a large surface area for antibody attachment and increased sensitivity. In addition, the advantages of the new immobilization platform were reusing the working electrode numerous times, recording repeatable and reproducible signals, and reducing the necessary volume of biomolecules. The specific interaction between cotinine and cotinine-specific antibody-attached magnetic nanoparticles restricted the electron transfer of the redox probe and changed the impedimetric response of the electrode correlated to the concentration of cotinine. The magneto biosensor had a wide detection range (2-300 pg/mL), a low LOD (606 fg/mL), and an acceptable recovery (97.24-105.31%) in real samples. In addition, the current biosensor's measurement results were in good agreement with those found by the standard liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA) methods. These results showed that a simple impedimetric immunosensing platform was generated for the cotinine analysis.
Celiac disease biomarker quantification in human fluid microenvironment: A selective and ultrasensitive magnetosensing immunoplatform
(Elsevier Science Sa, 2025) Aydin, Elif Burcu; Aydin, Muhammet; Sezginturk, Mustafa Kemal
An innovative magnetosensing strategy for highly sensitive impedimetric determination of anti-tissue transglutaminase antibodies (anti-tTG) was developed and applied successfully in real serum and saliva samples. The transducer surface of the proposed immunosensor consisted of an indium tin electrode (ITO) attached with poly (3-thienylacetic acid) (PTAc)-coated magnetic nanoparticles, which provided a very useful surface for the attachment of the biological molecules. The PTAc-coated magnetic nanoparticles were held by a magnetic field on the electrode surface, and the immunological reaction was carried out on magnetic nanoparticles as a solid platform on which the tissue transglutaminase (tTG) was covalently bound. With the specific capture of anti-tTG on the tTG-immobilized surface, an impedimetric signal was measured, and the electrochemical response of this specific reaction was correlated with the anti-tTG concentration. A linear relationship between the impedimetric signal and the anti-tTG concentration was obtained over a wide range of 0.125-25 U/mL. This magnetobiosensor illustrated a stable quantitative signal to anti-tTG concentrations after 45 minutes of incubation with a limit of detection of 0.034 U/mL and a low relative standard deviation (RSD) of 3.61 %, n = 3. This immunosensor's electrochemical behaviour was thoroughly examined, with consideration given to factors including sensitivity, specificity, repeatability, reproducibility, and storage stability. Lastly, serum and saliva samples were analyzed using the biosensor, and excellent correlation was achieved between the commercial ELISA kit and the proposed immunosensor. As a result, this approach held out a lot of hope for a straightforward, affordable, and user-friendly analytical technique that would enable the label-free measurement of anti-tTG levels.
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 Kemal
A 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.
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 Kemal
An 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.

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