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Öğe A Simple and Low-Cost Electrochemical Immunosensor for Ultrasensitive Determination of Calreticulin Biomarker in Human Serum(Wiley-V C H Verlag Gmbh, 2023) Aydın, Elif Burcu; Aydın, Muhammet; Sezgintürk, Mustafa KemalAn early on time detection of breast cancer significantly affects the treatment process and outcome. Herein, a new label-free impedimetric biosensor is developed to determine the lowest change in the level of calreticulin (CALR), which is a new biomarker of breast carcinoma. The proposed immunosensor is fabricated by using reduced graphene oxide/amino substituted polypyrrole polymer (rGO-PPyNH2) nanocomposite modified disposable electrode. The anti-CALR antibodies are first attached on the rGO-PPyNH2 nanocomposite coated electrode through glutaraldehyde crosslinking; the CALR antigens are then immobilized with the addition of CALR antigens to form an immunocomplex on the sensing surface. This immunocomplex induces considerably larger interfacial electron transport resistance (R-ct). The variation in the R-ct has a linear relationship with CALR level in the detection range of 0.025 to 75 pg mL(-1), with a detection limit of 10.4 fg mL(-1). The suggested biosensor shows high selectivity to CALR, good storage stability (at least 5 weeks) and suitable reproducibility results as shown in quality control chart. The designed immunosensor is utilized to analyze CALR levels in human sera with satisfying results. This immunosensor provides a novel way for the clinical determination of CALR and other cancer biological markers.Öğe Novel electrochemical biosensing platform based on conductive multilayer for sensitive and selective detection of CYFRA 21-1(Elsevier Science Sa, 2023) Aydın, Elif Burcu; Aydın, Muhammet; Sezgintürk, Mustafa KemalIn the present work, an electrochemical biosensor modified with a conductive multilayer composed of gold nanoparticles and amino-substituted-pyrrole polymer (AuNPs/P(PyAmn)) was constructed for label-free detec-tion of cytokeratin 19 fragment 21-1 (CYFRA 21-1), one of the most important lung cancer biomarkers. The electrochemical biosensor was fabricated by electropolymerization of PyAmn on an indium tin oxide (ITO) platform with electrodeposition of AuNPs and binding of an anti-CYFRA 21-1 recognition element on the P (PyAmn)-coated electrode via glutaraldehyde crosslinking. In the present immunosensor, AuNPs deposition provided excellent conductivity and good electron transfer. The electropolymerization of the P(PyAmn) polymer layer ensured a large surface area that increased the amount of anti-CYFRA 21-1 antibodies that could be attached. A specific immunoreaction occurred between anti-CYFRA 21-1 antibody and CYFRA 21-1 antigen when the immunosensor was successively reacted with the target CYFRA 21-1 protein. According to specific immu-noreactions, the resulting biosensor produced an impedimetric signal proportional to the amount of CYFRA 21-1 in the linear detection range of 0.015-90 pg/mL. With optimal fabrication parameters, the detection limit, quantification limit and sensitivity for CYFRA 21-1 were 4.59 pg/mL, 15.31 pg/mL and 0.21 k Omega pg(-1) mL cm(-2), respectively. Meanwhile, this biosensor had good stability and high specificity for CYFRA 21-1 detection, and it was successfully applied to real serum samples. It also had a satisfactory rate of R-2 = 0.9984. The use of a disposable ITO substrate as a basis for this immunosensor allowed the use of simple instrumentation. This study illustrates a new approach to fabricate an ultrasensitive and label-free electrochemical biosensor based on a disposable platform for CYFRA 21-1 analysis in clinical biosensing.Öğe Recent trends in the applications of polymer composite modified electrodes for biosensors(Elsevier, 2022) Aydın, Elif Burcu; Aydın, Muhammet; Sezgintürk, Mustafa KemalBiosensors have gained increasing significance in recent years on account of their many advantages, including low cost, simplicity of use, and portability. They are successful analytical sensing tools in detection of target analytes in various fields, such as clinical diagnosis, the food industry, environmental monitoring, and biosecurity. Among different immobilization support materials, polymer nanocomposites have been preferred in the construction of biosensors/sensors due to their promising characteristics of high mechanical and electrical features, good environmental stability, low cost, and good electrical conductivity. This chapter summarizes the recent advances in polymer nanocomposite modified biosensors and investigates their applications in biosensor fabrication. © 2023 Elsevier Ltd. All rights reserved.Öğe Biosensors for saliva biomarkers(Academic Press Inc., 2023) Aydın, Elif Burcu; Aydın, Muhammet; Sezgintürk, Mustafa KemalThe analysis of salivary biomarkers has gained interest and is advantageous for simple, safe, and non-invasive testing in diagnosis as well as treatment. This chapter explores the importance of saliva biomarkers and summarizes recent advances in biosensor fabrication. The identification of diagnostic, prognostic and therapeutic markers in this matrix enables more rapid and frequent testing when combined with the use of biosensor technology. Challenges and future goals are highlighted and examined. © 2023 Elsevier Inc.Öğe FMR1 Gene Mutation Analysis and CGG Repeat Number Distribution from a Single Center(Gazi Univ, Fac Med, 2022) Arıkan, Yunus; Bilgen, Türker; Mıhcı, Ercan; Duman, Özgür; Karaman, Tuğba; Keser, İbrahimBackground: Mutation occurring in fragile X mental retardation 1 (FMR1) gene is acknowledged as the most common cause for X chromosome linked intellectual disability/mental retardation (XLID/XLMR). This gene harbors unstable CGG triplet repeats within its 5'UTR (untranslated region). Loss of function of the FMR1, which is mostly due to the hypermethylation of the CpG islands on its promoter region, causes fragile X syndrome (FXS). Displaying different frequencies, the FXS is a common phenomenon all over the world, the studies focus mostly on the Caucasian population. Purpose: We aimed to reveal the CGG repeat number distribution and the mutation profile of the FMR1 gene in clinically pre-diagnosed FXS patients and in family members of the patients who were diagnosed as full mutation. Methods: We evaluated the copy number of the CGG triplets in 767 FXS patients and their family members in Antalya province by employing fragment analysis molecular technique. We also assessed, by segregation analysis, whether there is unusual genetic transmission pattern of CGGs. Results: The molecular analysis shows the most common copy numbers of CGGs are thirty, twenty-nine and thirty-one. Present study is the first report concerning Antalya city of Turkey about the frequencies of the normal CGG repeats number, grey-zone, pre-mutation and full mutations, we updated our molecular test results with two unusual transmittance patterns of the CGG repeats. Conclusion: Since the potential of CGG repeat properties may cause differential intergenerational transmission patterns, its' population specific evaluation can contribute to provide a better genetic diagnosis and genetic counseling services for the related clinical entities.Öğe In Silico Analysis of the Structural and Functional Consequences of Polymorphic Amino Acid Substitutions in the Cattle HSF1 Protein(Kafkas Univ, Veteriner Fakultesi Dergisi, 2022) Atalay, SertaçHeat stress causes a decrease in the productivity of livestock by negatively affecting some important economic features such as fertility, growth and milk production. The heat shock transcription factor 1 (HSF1) gene plays a key role in the regulation of the stress response. Therefore, the present study aimed to predict the most deleterious non-synonymous single nucleotide polymorphisms (nsSNP) on the cattle HSF1 gene via in silico analyses. Out of 170 nsSNPs in the HSF1 gene, 14 SNPs were predicted as deleterious by all the nine the vast majority of SNPs predicted to be deleterious were evolutionary conserved. Protein structural analyses were performed I-Mutant, Mupro, Hope Project server, RaptorX and Swiss Model server. The 12 amino acid substitutions (V15G, F18L, L19R, K21M, I35T, V46E, V56G, F61L, A67D, Y76D, V81G, L112P) in the DNA binding region of the cattle HSF1 protein were predicted to be highly deleterious. The P112 variant was predicted to disrupt an a-helix structure. It was determined that the two amino acid changes (K21M, Y76D) on the surface of the protein were different in terms of hydrophobicity, charge, and size. These variants (M21, D76) might hamper the protein's interaction with the heat shock elements.Öğe Label-free and reagent-less electrochemical detection of nucleocapsid protein of SARS-CoV-2: an ultrasensitive and disposable biosensor(Royal Soc Chemistry, 2022) Aydın, Elif Burcu; Aydın, 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 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) Aydın, Elif Burcu; Aydın, 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 Impedimetric Detection of Calreticulin by a Disposable Immunosensor Modified with a Single-Walled Carbon Nanotube-Conducting Polymer Nanocomposite(Amer Chemical Soc, 2022) Aydın, Elif Burcu; Aydın, 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 Effects of idiopathic erythrocytosis on the left ventricular diastolic functions and the spectrum of genetic mutations: A case control study(Lippincott Williams & Wilkins, 2022) Yeşilaltay, Alpay; Değirmenci, Hasan; Bilgen, Türker; Şirin, Duygu Yaşar; Bayır, Duygu; Değirmenci, Pelin; Turgut, BurhanBackground: We have aimed at exposing left ventricular diastolic functions and the presence of known genetic mutations for familial erythrocytosis, in patients who exhibit idiopathic erythrocytosis. Methods: Sixty-four patients with idiopathic erythrocytosis (mean age, 46.4 +/- 2.7 years) and 30 age-matched healthy subjects were prospectively evaluated. The regions of interest of the erythropoietin receptor, hemoglobin beta-globin, von Hippel-Lindau, hypoxia-inducible factor 2 alpha, and Egl-9 family hypoxia-inducible factor genes were amplified by PCR. Left ventricular (LV) mass was measured by M-mode and 2-dimensional echocardiography. LV diastolic functions were assessed by conventional echocardiography and tissue Doppler imaging. Results: As a result of genetic analyses, genetic mutations for familial erythrocytosis were detected in 5 patients. It has been observed in our study that the risk of cardiovascular disorders is higher in patients. Interventricular septum thickness, left atrial diameter, and some diastolic function parameters such as deceleration time and isovolumetric relaxation time have been found to be significantly higher in idiopathic erythrocytosis group than in the controls. Conclusion: This study has shown that LV diastolic functions were impaired in patients with idiopathic erythrocytosis. In this patient group with increased risk of cardiovascular disorders, the frequent genetic mutations have been detected in 5 patients only. Therefore, further clinical investigations are needed as novel genetic mutations may be discovered in patients with idiopathic erythrocytosis because of cardiovascular risk.Öğe Alloreactive memory B cell detection by flow cytometric cross match using polyclonally activated memory B cell culture supernatants(Elsevier, 2022) Akalan, Hande; Şirin, Duygu Yaşar; Yılmaz, İpek; Ata, Pınar; Kara, Veli Melih; Taşdemir, Nicel; Bilgen, Türker; Titiz, Mesut İzzetIn addition to alloantibodies, alloreactive memory B cell (mBC) evaluation has a potential for immunological risk assessment during transplantation processes. For the alloreactive mBCs evaluation currently, direct Flow Cytometric (FC) analysis using the HLA tetramer staining is an option. Evaluation of alloantibodies produced by the polyclonally stimulated alloreactive mBCs in in vitro culture system seems to be another useful approach, but this needs further downstream applications. In this study, we investigated the usefulness of the Flow Cytometric Cross Match (FCXM-supernatant) in which in vitro polyclonally activated mBCs culture supernatants and potential donor's lymphocytes being used for the mBC detection. FCXM-supernatant assays were performed between culture supernatants of polyclonally activated mBCs obtained from 4 allosensitized multiparous women and 14 renal transplant patients, and their non-alloimmunized spouses' or donors' lymphocytes, and vice versa. HLA typing was performed by SSP method. Anti-HLA antibodies produced by in vitro activated alloreactive mBCs were also evaluated by the Luminex assays. The success of in vitro polyclonal activation of mBCs was evaluated by a total IgG ELISA test and antibody secreting cell analyses by FC. Donor specific alloreactive mBCs were detected by FCXM-supernatant in 45% of the 18 allosensitized cases. Detection rate was 85% (6 out of 7) in the strongly allosensitized cases. No alloreactive mBCs was detected in control cases without allosensitization. FCXMsupernatant negative results of the allosensitized cases were related to low level of allosensitization and insufficient polyclonal stimulation evaluated by total IgG antibody tests of the supernatants. We herein report a practical methodology for alloreactive mBC detection as a donor specific manner using the FCXM-supernatant assay so that this would easily be transformed into a routine test performed in tissue typing laboratories.Öğe Investigation of alpha globin gene mutations by complementary methods in Antalya(Yuzuncu Yil Universitesi Tip Fakultesi, 2021) Keser, İbrahim; Mercan, T.K.; Bilgen, Türker; Kupesiz, O.A.; Arikan, Y.; Canatan, D.Alpha (?) thalassemia is one of the hemoglobinopaties that is inherited by autosomal recessive mode. It is caused by mutations on alpha-1 and alpha-2 globin genes. Deletional type mutations of globin genes have commonly been seen in alpha thalassemias. While small deletional mutations such as-3.7 cause ?+-thalassemia, large deletions such as-26.5-20.5 cause ?0-thalassemia. The objective of our study was to determine the profile of deletional and non-deletional ?-globin gene mutations in the Antalya population, Turkey. In present study, the presence of ?-thalassemia mutations were investigated by RDBH (reverse dot blot hybridization) among 250 patients with microcytic anemia and beta globin normal. Some positive and negative cases were confirmed by MLPA (multiplex ligation dependent probe amplification) and at the latest DNA sequencing. Eight different mutations were determined in 112 (44.8%) of patients in our study. The-??3.7 deletion was the most common mutation(73.3%). Others common mutations were the – ?20.5 (13.0%) and –MED (6.5%),--FIL (2.4%), Hb Adana (2.4%). The 97.5 % of total mutations consisted of these five mutations. Three patients with Hb H disease were found related with-? 3.7 /-(?)-20.5 genotype. One patient (2.04%) had the ??? anti-3.7 gene triplication. Two rare mutations, ?2 codon 64 (G>C) (Hb Fontainebleau) and ?2 codon 193 (G>A) (Hb G-Waimanalo), were determined by DNA sequencing firstly in Antalya Province, Turkey. Our results may be valuable to give accurate premarital genetic counseling and to apply classical prenatal and preimplantation genetic diagnosis by the complementary methods such as RDBH, MLPA and DNA sequencing for the screening of alpha thalassemia carriers. © 2021, Yuzuncu Yil Universitesi Tip Fakultesi. All rights reserved.Öğe A Label-free Electrochemical Immunosensor for Highly Sensitive Detection of TNF alpha, Based on Star Polymer-modified disposable ITO Electrode(Bentham Science Publ Ltd, 2021) Aydın, Elif Burcu; Aydın, Muhammet; Sezgintürk, Mustafa KemalBackground: Biomarkers are very important disease-related biomolecules which should be analyzed sensitive and selective in related physiological fluids or tissues. Tumor necrosis factor-alpha is a type of cytokine which plays vitlly important roles in different methabolic pathways such as cell death, survival, differentiation, proliferation and migration, and infectious and inflammatory diseases including rheumatoid arthritis, diabetes. Objective: In this study, it was aimed to develop a reliable tool based on star-shaped poly(glycidyl methacrylate) polymer coated disposable indium tin oxide electrode for determination of Tumor necrosis factor-alpha, an important disease biomarker. Methods: Star shaped polymer was used as an interface material for anti- Tumor necrosis factor alpha antibodies immobilization. The antibodies were immobilized covalently onto polymer coated indium tin oxide electrode. Electrochemical impedance spectroscopy and cyclic voltammetry techniques were used for all electrochemical measurements. Results: The suggested immunosensor exhibited a linear range between 0.02 and 4 pg/mL Tumor necrosis factor-alpha, and the detection limit was found as 6 fg/mL. Scanning electron microscopy and atomic force microscopy were used for electrode surface characterization. In addition, the suggested immunosensor was used for Tumor necrosis factor-alpha sensing in human serum samples. The results displayed recoveries between 97.07 and 100.19%. Moreover, this immunosensor had a simple fabrication procedure and a long storage-stability. Conclusion: A new biosensor based on a Star shaped polymer for the ultra sensitive determination of a biomarker Tumor necrosis factor-alpha was developed. The biosensor presented excellent repeatability and reproducubility, and also wide calibration range for Tumor necrosis factor-alpha.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) Aydın, Elif Burcu; Aydın, 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.Öğe A label-free and sensitive impedimetric immunosensor for TNF ? biomarker detection based on epoxysilane-modified disposable ITO-PET electrode(Taylor and Francis Ltd., 2020) Burcu Aydın, E.The present study constructed a simple and cost-effective electrochemical immunosensor based on 3-glycidoxypropyltriethoxysilane (GPTES) monolayer coated indium tin oxide-polyethylene terephthalate (ITO-PET) electrode for selective and sensitive determination of Tumour necrosis factor ? (TNF ?) cancer biomarker. GPTES was a well-known surface coupling silane agent which had epoxy groups to bind antibodies. Anti-TNF ? antibodies were chosen as biorecognition elements and they attached covalently on the GPTES modified ITO-PET electrode. Electrochemical determination of immunoreaction between anti-TNF ? antibodies and TNF ? antigens was the basic principle of the proposed immunosensor. The electrochemical characterisation of the designed biosensor was tested with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. In addition, the surface morphological characteristics of the ITO-PET electrodes after several modification stages were monitored by scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging. The analytical success of the proposed immunosensor was tested with respect to linear detection range, detection limit, repeatability, reproducibility, reusability, regeneration and long-term stability. The present biosensor had a wide linear range from 0.01 to 1.5 pg/mL and a low detection limit of 3.1 fg/mL. Finally, the biosensor successfully detected TNF ? cancer biomarker in human serum samples with high recovery ranges. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.Öğe Paper-based devices(Elsevier, 2020) Aydın, Elif Burcu; Aydın, Muhammet; Sezgintürk, Mustafa KemalBiosensors are promising tools in several areas such as clinical diagnosis, food analyses, environment monitoring, and in other fields, where rapid and reliable analyses are needed. Today they are represented on the market worldwide by an increasing number of paper-based electrodes working in these areas. Paper-based electrodes for glucose monitoring have been commercially available for about 25 years. Apart from glucose monitoring by using paper-based electrodes, commercials tests are now available for metabolites, human chorionic gonadotrophin, C-reactive protein, troponin, myoglobin, human immunodeficiency virus, influenza A and B, streptococcus A, Helicobacter pylori, adenovirus and rotavirus, malaria, tuberculosis, hepatitis A/B/C, and cancer biomarkers measurements in human fluids. Other application points of these paper-based commercial tests are food, environment, and biothreat applications. Such tests are successfully applied in home, office, hospitals, and clinics. In this chapter, the commercial tests used for clinical, food, environmental, and biothreat analyses in global market are reviewed and the specific features of these tests are summarized. © 2020 Elsevier Inc. All rights reserved.Öğe Biosensors in Drug Discovery and Drug Analysis(Bentham Science Publ Ltd, 2019) Aydın, Elif Burcu; Aydın, 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 Ultrasensitive determination of cadherin-like protein 22 with a label-free electrochemical immunosensor using brush type poly(thiophene-g-glycidylmethacrylate) modified disposable ITO electrode(Elsevier Science Bv, 2019) Aydın, Elif Burcu; Aydın, Muhammet; Sezgintürk, Mustafa KemalA label-free immunosensor for the determination of Cadherin-like protein 22 (CDH 22) was successfully developed by using poly(thiophene-g-glycidyl methacrylate) (PT-GMA) brush type polymer modified disposable ITO electrode. This immunosensor was fabricated by immobilizing of anti-CDH 22 antibodies on epoxy functional groups of brush type polymer. Brush type polymer was coated on the disposable ITO electrode by utilizing the spin-coating method. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) analyses were employed for monitoring of electrochemical properties of the immunosensor. Single frequency impedance (SFI) analysis was utilized to investigate the specific recognition interaction between anti-CDH22 antibody and CDH22 antigen. Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to prove the attachment of anti-CDH 22 antibodies on the electrode surface. Atomic force microscopy (AFM) and Scanning electron microscopy (SEM) analyses were carried out to indicate the changes formed on the sensing interface during the immobilization process. The electrochemical signals in response to different concentrations of CDH 22 antigens were evaluated with EIS measurements under the optimal experimental conditions. With the increase of concentrations of CDH 22 antigens, a thick protein layer was obtained on the electrode surface, resulting in higher electrochemical signals. The variations in impedance values were proportional to the CDH22 concentrations, with a wide linear detection range of 0.01-3 pg/mL, and a low detection limit of 3.2 fg/mL. The suggested immunosensor was an easy and low-cost label-free detection technique and provided a simple way for determination of cancer biomarkers such as CDH 22.Öğe Advances in electrochemical immunosensors(Elsevier Academic Press Inc, 2019) Aydın, Elif Burcu; Aydın, 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 A sensitive and selective approach for detection of IL 1? cancer biomarker using disposable ITO electrode modified with epoxy-substituted polythiophene polymer(Elsevier Ltd, 2019) Aydın, MuhammetA highly sensitive and label-free electrochemical immunosensor for sensitive detection of interleukin 1? cancer biomarker was described by using epoxy-substituted polythiophene polymer modified disposable indium tin oxide electrode. This conjugated polymer was synthesized to fabricate this immunosensor for the first time and it offered a good biosensing platform for anti-IL 1? antibody immobilization due to epoxy groups present on the side groups of the polymer. Furthermore, the epoxy-substituted polythiophene polymer coated indium tin oxide electrode was used for the determination of IL 1? antigen for the first time. Electrode fabrication stages were characterized by using electrochemical (electrochemical impedance spectroscopy and cyclic voltammetry) and morphological (scanning electron microscopy and atomic force microscopy) techniques. Under optimum experimental conditions, impedimetric responses of the immunosensor increased with the increasing of IL 1? antigen concentration, and the proposed immunosensor displayed a wide linear detection range from 0.01 pg/mL to 5.5 pg/mL with a detection limit of 3.4 fg/mL. The proposed immunosensor exhibited outstanding performance including excellent reproducibility, good repeatability, high selectivity and long storage stability. With the advantages of simple operation, low-cost fabrication and label-free format, the suggested immunosensor was expected to have potential applications for IL 1? cancer biomarker detection. © 2019 Elsevier B.V.
