Browsing by Author "Ozkan-Ariksoysal, Dilsat"

Now showing 1 - 4 of 4

Electrochemical Biosensing: From Interaction Between Epilobium Species and Dna To an Approach To Detect New Electroactive Components in Plant Extracts and Their Effects on Dna
(Springer Heidelberg, 2024) Subak, Hasret; Dalar, Abdullah; Mukemre, Muzaffer; Ozkan-Ariksoysal, Dilsat
Here, a simple and label-free biosensor based on disposable pencil graphite electrode (PGE) was developed for the first time to investigate the interaction between Epilobium sp. plant extract containing active compounds (quercetin and kaempferol) and DNA using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The solution of extract was interacted with calf thymus double-stranded DNA (dsDNA) which immobilized onto the biosensor surface by simple adsorption. The effect of Epilobium on double-stranded DNA (dsDNA) was then analyzed by monitoring the changes in electrochemical signals arising from both guanine bases in DNA and the electroactive compounds in Epilobium extract. Epilobium content was also detected by using HPLC/MS/MS technique, and the gained results were compared with those obtained by electrochemical method. It was found that both methodologies supported each other in terms of active ingredients in Epilobium sp. Numerous factors affecting the extract-DNA interaction were optimized such as Epilobium concentration, interaction time. The developed DNA sensor can well detect Epilobium extract-DNA interaction in 60-min detection time with 26 ng of detection limit in 50 mu L of sample volume with a linear range from 1 to 10 mu g/mL. This study includes alternative method that can be used to detect new electroactive components present or to be found in different plant extracts and their interactions with DNA.
Label-Free Electrochemical Biosensor for the Detection of Influenza Genes and the Solution of Guanine-Based Displaying Problem of Dna Hybridization
(Elsevier Science Sa, 2018) Subak, Hasret; Ozkan-Ariksoysal, Dilsat
The differentiation of fully matched and unlabelled Influenza A (Inf A) or B (Inf B) target DNA obtained from polymerase chain reaction (PCR)-amplified real samples towards non-complementary sequences have been analyzed with an extremely simple electrochemical methodology by developed label-free electrochemical DNA biosensor without any surface modification. In the meanwhile, this is the first study that contains the solution of the guanine signal-based displaying problem of DNA hybridization which has been solved by designed biosensor. The monitoring of guanine oxidation signal affected by experimental conditions and the response showed significant differences depending on the nature and composition of DNA. In the presented work, the effect of differences in the number of inosine in probe DNA on hybridization imaging was also discussed. The electrochemical oxidation of guanine (approximately +1.00V) was measured at pencil graphite electrode (PGE) by using differential pulse voltammetry (DPV) technique and evaluated before and after hybridization between probe and target DNAs. Several hybridization solutions and rinsing protocols with different ionic strengths have been utilized to achieve optimum hybridization displaying response. The selectivity of developed genosensor was also tested at the same time with hybridization. The detection limits of sensors were calculated as 35 nM for Inf A and 21 nM for Inf B sequences. (C) 2018 Elsevier B.V. All rights reserved.
Mycotoxins Aptasensing: From Molecular Docking To Electrochemical Detection of Deoxynivalenol
(Elsevier Science Sa, 2021) Subak, Hasret; Selvolini, Giulia; Macchiagodena, Marina; Ozkan-Ariksoysal, Dilsat; Pagliai, Marco; Procacci, Piero; Marrazza, Giovanna
This work proposes a voltammetric aptasensor to detect deoxynivalenol (DON) mycotoxin. The development steps of the aptasensor were partnered for the first time to a computational study to gain insights onto the molecular mechanisms involved into the interaction between a thiol-tethered DNA aptamer (80mer-SH) and DON. The exploited docking study allowed to find the binding region of the oligonucleotide sequence and to determine DON preferred orientation. A biotinylated oligonucleotide sequence (20mer-BIO) complementary to the aptamer was chosen to carry out a competitive format. Graphite screen-printed electrodes (GSPEs) were electrochemically modified with polyaniline and gold nanoparticles (AuNPs@PANI) by means of cyclic voltammetry (CV) and worked as a scaffold for the immobilization of the DNA aptamer. Solutions containing increasing concentrations of DON and a fixed amount of 20mer-BIO were dropped onto the aptasensor surface: the resulting hybrids were labeled with an alkaline phosphatase (ALP) conjugate to hydrolyze 1-naphthyl phosphate (1-NPP) substrate into 1-naphthol product, detected by differential pulse voltammetry (DPV). According to its competitive format, the aptasensor response was signal-off in the range 5.0-30.0 ng.mL(-1) DON. A detection limit of 3.2 ng.mL(-1) was achieved within a 1-hour detection time. Preliminary experiments on maize flour samples spiked with DON yielded good recovery values. (C) 2020 Elsevier B.V. All rights reserved.
Ready-To Diagnostic Kit Based on Electrochemical Nanobiosensor for Antibiotic Resistance Gene Determination
(Elsevier, 2024) Subak, Hasret; Yilmaz, Fethiye Ferda; Ozkan-Ariksoysal, Dilsat
Nowadays, antibiotic resistance, which occurs as a result of mutations in bacterial genes due to the frequent use of antibiotics, causes serious health problems and deaths. One of the resistance mechanisms that develop with the use of antibiotics is that bacteria begin to produce carbapenemase enzymes that cause multiple drug resistance in bacteria by hydrolyzing antibiotics. In this study, an alternative diagnostic kit method to traditional tests was developed for the determination of bacteria carrying relevant antibiotic resistance genes because these analyzes have multi-step sample preparation, long/complex determination schemes and are high cost. With the diagnostic kit containing a stable electrochemical nanobiosensor developed in this study, the presence of two different antibiotic resistance gene regions of the carbapenemase enzyme named OXA-48 and VIM, which are responsible for more than 50 % of deaths due to antibiotic resistance, was investigated. Carbon nanotubes (CNTs) has been modified to the pencil graphite electrode (PGE), then the synthetic capture probe DNAs are immobilized covalently to the surface containing nanomaterial. Later, the sensor surface, whose stability was ensured by surface blockage, thus gained "diagnostic kit feature" and was stored in the refrigerator (+4 degrees C) until analysis. Thus, the preparation of a ready-to-analyze diagnostic kit, which will provide detection without any preparation, has been completed. With the developed kit, it was possible to determine the resistance gene with 2.5 pmole/50 mu L of detection limit. In addition, analyzes with real samples could be performed even after 150 days (5 months) of kit preparation. This represents the first diagnostic kit system containing PGE and CNT for the detection of antibiotic resistance based on electrochemical alpha naphthol signal measurement in real samples with symmetrical and asymmetric structures (PCR). In the developed alternative test platform, the sample volume required for determination is 50 mu L and the analysis time with this portable open-use and throw-away diagnostic kit is 30 min.