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Öğe A Bottom-Up Approach for Developing Aptasensors for Abused Drugs: Biosensors in Forensics(Mdpi, 2019) Aydindogan, Eda; Balaban, Simge; Evran, Serap; Coskunol, Hakan; Timur, SunaAptamer-based point-of-care (POC) diagnostics platforms may be of substantial benefit in forensic analysis as they provide rapid, sensitive, user-friendly, and selective analysis tools for detection. Aptasensors have not yet been adapted commercially. However, the significance of the applications of aptasensors in the literature exceeded their potential. Herein, in this review, a bottom-up approach is followed to describe the aptasensor development and application procedure, starting from the synthesis of the corresponding aptamer sequence for the selected analyte to creating a smart surface for the sensitive detection of the molecule of interest. Optical and electrochemical biosensing platforms, which are designed with aptamers as recognition molecules, detecting abused drugs are critically reviewed, and existing and possible applications of different designs are discussed. Several potential disciplines in which aptamer-based biosensing technology can be of greatest value, including forensic drug analysis and biological evidence, are then highlighted to encourage researchers to focus on developing aptasensors in these specific areas.Öğe Catechol-Attached Polypeptide with Functional Groups as Electrochemical Sensing Platform for Synthetic Cannabinoids(Amer Chemical Soc, 2020) Durmus, Ceren; Aydindogan, Eda; Gumus, Zinar Pinar; Endo, Takeshi; Yamada, Shuhei; Coskunol, Hakan; Yagci, YusufHerein, we first constructed a functional surface using a catechol-attached polypeptide (CtP) for the detection of JWH-018 (N-4-hydroxypentyl metabolite). K2 antibody was then incorporated to the polymer via covalent cross-linker. Step-by-step modifications on the glassy carbon electrode surface were characterized by electrochemical measurements such as differential pulse voltammetry, cyclic voltammetry, impedance spectroscopy, and X-ray photoelectron spectroscopy. Linearity and the limit of detection for JWH-018 (N-4-hydroxypentyl metabolite) were determined as 10-500 ng/mL with an equation of y = 0.0018x + 0.136 (R-2 = 0.993) and 5.892 ng/mL, respectively. the selectivity of the biosensor was evaluated with different interfering molecules (methamphetamine, codeine, and cocaine). Finally, the biosensor was successfully used in the determination of JWH-018 (N-4-hydroxypentyl metabolite) in spiked synthetic urine samples, and a high-performance liquid chromatography (HPLC) system was used as a reference method to confirm the sample application. the results show that this biosensor platform can be applied to detect other JWH series of synthetic cannabinoids with high sensitivity and accuracy.Öğe An Electrochemical Biosensor Platform for Testing of Dehydroepiandrosterone 3-Sulfate (DHEA-S) as a Model for Doping Materials(Wiley-V C H Verlag Gmbh, 2019) Balaban, Simge; Durmus, Ceren; Aydindogan, Eda; Gumus, Zinar Pinar; Timur, SunaEndogenous steroids such as dehydroepiandrosterone (DHEA) and dehydroepiandrosterone 3-sulfate (DHEA-S) have commonly used as doping materials by athletes and to date novel techniques are needed for detection of these molecules. In this study, antibody-based electrochemical biosensor has developed for testing level of the DHEA-S. For this aim, gold surfaces were initially modified with cysteamine (Cys) and then, DHEA-S antibody was immobilized on the surface via glutaraldehyde (GA) as a crosslinking agent. The stepwise modification of electrode surface was monitored by using various electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Linear range was determined as 2.5-100 ng/mL DHEA-S using differential pulse voltammetry (DPV) technique, as well. Moreover, repeatability (+/- S.D.), coefficient of variation (%) and limit of detection (LOD) values were calculated as 0.033, 1.030 and 3.971, respectively. Also, DHEA-S in synthetic serum and urine samples were successfully determined with standard addition method and confirmation analysis were performed with liquid chromatography quadrupole-time of flight mass spectrometry (LC-QTOF/MS) system. The selectivity was studied with the addition of some interfering molecules (testosterone, bovine serum albumin (BSA), cholesterol, uric acid, lactic acid, codein (COD), ascorbic acid, DHEA). Consequently, this work is proposed as practical, innovative and cost-effective technique that can be easily adapted for the miniaturized form for the analysis of other doping substances as well as DHEA-S for the future works.Öğe An Electrochemical Biosensor Platform for Testing of Dehydroepiandrosterone 3-Sulfate (DHEA-S) as a Model for Doping Materials(Wiley-V C H Verlag Gmbh, 2020) Balaban, Simge; Durmus, Ceren; Aydindogan, Eda; Gumus, Zinar Pinar; Timur, SunaEndogenous steroids such as dehydroepiandrosterone (DHEA) and dehydroepiandrosterone 3-sulfate (DHEA-S) have commonly used as doping materials by athletes and to date novel techniques are needed for detection of these molecules. In this study, antibody-based electrochemical biosensor has developed for testing level of the DHEA-S. For this aim, gold surfaces were initially modified with cysteamine (Cys) and then, DHEA-S antibody was immobilized on the surface via glutaraldehyde (GA) as a crosslinking agent. The stepwise modification of electrode surface was monitored by using various electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Linear range was determined as 2.5-100 ng/mL DHEA-S using differential pulse voltammetry (DPV) technique, as well. Moreover, repeatability (+/- S.D.), coefficient of variation (%) and limit of detection (LOD) values were calculated as 0.033, 1.030 and 3.971, respectively. Also, DHEA-S in synthetic serum and urine samples were successfully determined with standard addition method and confirmation analysis were performed with liquid chromatography quadrupole-time of flight mass spectrometry (LC-QTOF/MS) system. The selectivity was studied with the addition of some interfering molecules (testosterone, bovine serum albumin (BSA), cholesterol, uric acid, lactic acid, codein (COD), ascorbic acid, DHEA). Consequently, this work is proposed as practical, innovative and cost-effective technique that can be easily adapted for the miniaturized form for the analysis of other doping substances as well as DHEA-S for the future works.Öğe A Functional Platform for the Detection of JWH-073 as a Model for Synthetic Cannabinoids(Wiley-V C H Verlag Gmbh, 2018) Sengel, Tulay Yilmaz; Celik, Emine Guler; Aydogan, Cansu; Gumus, Zinar Pinar; Ilktac, Raif; Aydindogan, Eda; Ciftci, Mustafa; Aldemir, Ebru; Coskunol, Hakan; Timur, Suna; Yagci, YusufDuring the last decade, progress has been made in the on-site detection of abused drug use. Herein, we present an electrochemical biosensor for the detection of one of the synthetic cannabinoids (SCs), JWH-073, using poly (methyl methacrylate) (PMMA) hyperbranched copolymer (HBC) as a base coating and antibody molecules to bind the JWH-073 to the surface. Modification of the surface is proved with various techniques such as differential pulse voltammetry, cyclic voltammetry, and electrochemical impedance spectrometry. The limit of detection and linearity (in logarithmic scale) for JWH-073 were found to be 31.87 ng/mL and 25-500 ng/mL, respectively. The selectivity of the proposed biosensor was also tested in the presence of interfering molecules and the response was much higher for JWH-073 in all measurements. In the final part of the study, synthetic urine was tested with the device and the relative standard deviation value was calculated to be less than 5.0%. The confirmation of data from the resulting bio-platform was performed via LC-QTOF/MS. This work is the first of its kind, a novel, rapid, cost-effective sensing platform for the detection of the SC.Öğe Laser-scribed Graphene Electrodes as an Electrochemical Immunosensing Platform for Cancer Biomarker 'eIF3d'(Wiley-V C H Verlag Gmbh, 2021) Balaban, Simge; Beduk, Tutku; Durmus, Ceren; Aydindogan, Eda; Salama, Khaled Nabil; Timur, SunaeIF3d is a protein biomarker which has a potential for the diagnosis of various cancers. Herein, a bio-platform was constructed for eIF3d sensing by using LSG and surface functionalization with anti eIF3d antibody via EDC/NHS chemistry. Following the surface modifications, XPS and several electrochemical methods were used. Difference in the signals were related to biomarker amounts between 75-500 ng/mL. LOD was calculated as 50.4 ng/mL. Selectivity of biosensor was tested by using of various interference molecules. EIF3d was also successfully detected in synthetic biological samples. Thus, to the best of our knowledge, this study is one of the rare studies on use of LSGs in immunosensor studies.Öğe Paper-Based Analytical Methods for Smartphone Sensing with Functional Nanoparticles: Bridges from Smart Surfaces to Global Health(Amer Chemical Soc, 2018) Aydindogan, Eda; Celik, Emine Guler; Timur, SunaÖğe Paper-based colorimetric spot test utilizing smartphone sensing for detection of biomarkers(Elsevier, 2020) Aydindogan, Eda; Ceylan, Ayse Elcin; Timur, SunaThe need for a continuous, real-time monitoring of specific diseases represents an unmet scientific need. Evidently, cancer is one of the most important diseases where it is crucial to increase the rates of patient survival and monitor disease prognosis. Herein, a novel type of immunoassay was developed for detection of cancer biomarkers, using alpha-fetoprotein (AFP) and mucin-16 (MUC16) as model analytes. Using gold nanoparticle (AuNP) bioconjugates as a signal production tool, relevant antibody (Ab)-conjugated AuNPs were prepared on the nitrocellulose (NC) membrane. To construct a spot-like point-of-care (POC) immunoassay, cysteamine conjugated AuNPs (AuNP-Cys) were immobilized on the NC membrane and antibodies were conjugated to the nanoparticle on the detection pad, following a treatment with the samples that contains AFP or MUC16 which are well-known protein biomarkers for liver and ovarian cancer. By using the change in the colorimetric properties of AuNPs, detection of tumor markers was achieved by using a smartphone image and color analysis software at the final stage. Image J application was used for the evaluation of color changes depending on the biomarker concentration in buffer or spiked synthetic serum samples. the linear range was found as 0.1 ng/mL-100 ng/mL for AFP and 0.1-10 ng/mL for MUC16. Limit-of-detection (LOA) was calculated as 1.054 ng/mL and 0.413 ng/mL for AFP and MUC16, respectively. Interferent molecules, Her2, Immunoglobulin G (IgG) and bovine serum albumin (BSA) were tested on the system. Furthermore, synthetic serum samples spiked with selected analyte molecule were applied on the system and measured successfully.Öğe Surface Modification with a Catechol-Bearing Polypeptide and Sensing Applications(Amer Chemical Soc, 2018) Aydindogan, Eda; Celik, Emine Guler; Demirkol, Dilek Odaci; Yamada, Shuhei; Endo, Takeshi; Timur, Suna; Yagci, YusufA novel catechol-bearing polypeptide (CtP) was synthesized and used as a component of electrochemical biosensor involving both enzymatic activity and affinity-based sensing systems. Glucose oxidase (GOx) and anti-immunoglobulin G (Anti-IgG) were selected as model biorecognition elements for the selective analysis of glucose and IgG. Step-by-step surface modifications were followed using various techniques such as cyclic voltammetry (CV) and electrochemical impedance spectrometry (EIS) as well as X-ray photoelectron spectroscopy (XPS). Additionally, contact angles were measured in order to observe surface properties. Amperometric measurements using the GOx biosensor were performed at -0.7 V by following the oxygen consumption due to the enzymatic reaction in different glucose concentrations. Affinity-based interactions via IgG sensor were monitored using the differential pulse voltammetry (DPV) technique. As the "surface design with CtP" approach employed herein is generally applicable and easily adaptable to obtain functional matrices for biomolecule immobilization, CtP-coated surfaces can be promising platforms for the fabrication of various biobased sensing systems.Öğe Systematic review on recent potential biomarkers of chronic obstructive pulmonary disease(Taylor & Francis As, 2019) Aydindogan, Eda; Penque, Deborah; Zoidakis, JeromeIntroduction: Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death worldwide and associated with decreased lung function and inflammation. The heterogeneity of COPD and its molecular and clinical features hinder efficient patient stratification and introduction of personalized therapeutic approaches. The available clinical tools do not efficiently predict the progression and exacerbations of the disease. Areas covered: An overview of the most recent studies on putative COPD protein biomarkers and the challenges for implementing their use in the clinical setting is presented. Expert commentary: Proteomics biomarker discovery in COPD has mostly focused on approaches evaluating specific proteins on a limited number of samples. The most promising protein candidates can be classified into five main biological categories: extracellular matrix (ECM) remodeling, inflammation/immune response, oxidative stress response, vascular tone regulation, and lipid metabolism. To efficiently stratify COPD patients and predict exacerbations, it will be necessary to implement biomarker panels to better represent the complex pathophysiology of this disease. The application of unbiased proteomics and bioinformatics followed by appropriate clinical validation studies will contribute to the achievement of this aim while increasing the number of validated biomarkers that can enter the qualification processes by the regulatory entities.
