Current Perspectives in Graphene Oxide-Based Electrochemical Biosensors for Cancer Diagnostics

Since the first commercial biosensor device for blood glucose measurement was introduced in the 1970s, many biosensor types have been developed, and this research area remains popular worldwide. In parallel with some global biosensor research reports published in the last decade, including a great deal of literature and industry statistics, it is predicted that biosensor design technologies, including handheld or wearable devices, will be preferred and highly valuable in many areas in the near future. Biosensors using nanoparticles still maintain their very important place in science and technology and are the subject of innovative research projects. Among the nanomaterials, carbon-based ones are considered to be one of the most valuable nanoparticles, especially in the field of electrochemical biosensors. In this context, graphene oxide, which has been used in recent years to increase the electrochemical analysis performance in biosensor designs, has been the subject of this review. In fact, graphene is already foreseen not only for biosensors but also as the nanomaterial of the future in many fields and is therefore drawing research attention. In this review, recent and prominent developments in biosensor technologies using graphene oxide (GO)-based nanomaterials in the field of cancer diagnosis are briefly summarized

Label-free electrochemical biosensor for the detection of Influenza genes and the solution of guanine-based displaying problem of DNA hybridization

WOS: 000427704400023The 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.Project Coordination Department of Ege University, Izmir, Turkey [12/ECZ/033]D.O-A. would like to thank Project Coordination Department of Ege University (Project number 12/ECZ/033), Izmir, Turkey for their financial support. D.O-A. also acknowledges technical support from the Pharmaceutical Sciences Research Centre (FABAL) of Ege University, Faculty of Pharmacy. The Authors acknowledge to Prof. A. Arzu Sayiner for her technical support

Label-free detection of telomerase activity using guanine electrochemical oxidation signal

WOS: 000250937500051PubMed ID: 17927276Telomerase is an important biomarker for cancer cells and its activation in 85% of all cancer types confers a clinical diagnostic value. A label-free electrochemical assay based on guanine oxidation signal to measure telomerase activity is described. This developed technology combined with a disposable sensor, carbon graphite electrode (CGE), and differential pulse voltammetry (DPV) was performed by using PCR amplicons with/without telomeric repeats as the guanine oxidation signal observed at +1.0 V measured after the immobilization of PCR products. Guanine oxidation signal was chosen as a measure of telomerase activity because a substantial increase in the number of guanines was introduced by the action of telomerase which adds hexameric repeats (TTAGGG)(n) that contain 50% guanine. The developed assay was shown to specifically measure telomerase activity from cell extracts, and elongation rates increased linearly in a concentration dependent manner. Telomerase activity could be detected in cell extracts containing as low as 100 ng/mu L of protein. All of the electrochemical measurements were also confirmed with the conventional TRAP-silver staining assay. Rapidity, simplicity, and the label-free nature of the developed assay make it suitable for practical use in quantitative determination of telomerase activity from clinical samples for diagnosis of cancer

Different DNA Immobilization Strategies for the Interaction of Anticancer Drug Irinotecan with DNA Based on Electrochemical DNA Biosensors

WOS: 000280524700004PubMed ID: 20426745The interaction of anticancer drug irinotecan (CPT-11), which is the inhibitor of the Topoisomerase I enzyme, with fish sperm double stranded deoxyribonucleic acid (dsDNA) and synthetic short oligonucleotides were studied electrochemically based on the oxidation signals of guanine and CPT-11 by using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) at pencil graphite electrode (PGE). In this work, three types of methods, such as adsorption, covalent attachment and electrostatic binding were used for the immobilization of DNA onto the PGE surface. It is found that an effective modification method for DNA on the electrode surface is very important because it effects the drug and DNA interaction. As a result of the interaction, the electrochemical signal of guanine and CPT-11 greatly decreased. Experimental parameters, such as the effect of buffer solution on the interaction between CPT-11 and DNA, the concentration of CPT-11/DNA, the immobilization time of DNA and the accumulation time of CPT-11 were studied in DPV; in addition, the interaction of CPT-11 with oligonucleotides was evaluated for using as a hybridization indicator in CV and DPV. The detection limit and the reproducibility were also determined

A nucleic acid-based electrochemical biosensor for the detection of influenza B virus from PCR samples using gold nanoparticle-adsorbed disposable graphite electrode and Meldola's blue as an intercalator

WOS: 000292979500025In the presented study, a novel method is introduced that demonstrates the electrochemical detection of influenza B virus based on DNA hybridisation. The detection utilised gold nanoparticles (AuNPs) and Meldola's Blue (MDB), which is utilised as an intercalator label. The developed methodology, combined with a disposable pencil graphite electrode (PGE) and differential pulse voltammetry (DPV), was performed using both synthetic oligonucleotides and polymerase chain reaction (PCR) amplicons. The electrochemical oxidation response of guanine (approximately +0.1 V) and the voltammetric reduction signal of MDB (approximately -0.2 V) were measured before and after hybridisation reactions between a single strand DNA probe and its complementary target strain (synthetic target or denatured PCR samples). Before the immobilisation of the synthetic DNA probe of influenza type B virus, the transducer surface was interacted with AuNPs solution using a simple wet adsorption method. AuNP immobilisation was confirmed with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) to characterise the recognition surface of the genosensor. After the interaction between the PGE and AuNPs, a thiol-linked DNA probe was immobilised onto the nanoparticle-covered surface. When hybridisation occurred between the probe and its synthetic targets or specific PCR products, the highest MDB signal was observed. The probes were also challenged with equal quantities of non-complementary DNA at the PGE surface for the determination of biosensor selectivity. AuNP-coated electrodes showed high sensitivity and selectivity, specifically in real samples for the detection of the hybridisation reaction. The results obtained in the presented study indicated that the electrode surface area could be enhanced with AuNPs. The detection limit of the genosensor was found to be 54 picomoles for the synthetic target and 3.3 x 10(7) molecules for the real samples (PCR) in 30 mu L of sample volume. Future prospects and analytical performance of the sensor is briefly discussed.TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [SBAG-107S163]; Pharmaceutical Sciences Research Centre (FABAL) of Ege University, Faculty of PharmacyEge UniversityThe authors acknowledge financial support from TUBITAK (Projects SBAG-107S163) and the Pharmaceutical Sciences Research Centre (FABAL) of Ege University, Faculty of Pharmacy