Guanine Signal Research Articles

Electrochemical biosensing of Acinetobacter baumannii gene using chitosan-gold composite modified electrode

In this study, a novel electrochemical biosensor was developed for the sensitive and selective detection of the Acinetobacter baumannii gene sequence. The biosensor was created by immobilizing a capture probe specific to the A. baumannii gene on the surface of chitosan-gold modified pencil graphite electrodes. Following solid-state hybridization on the Chit-Au/PGE surface, the target DNA sequence of the A. baumannii was detected by measuring the guanine signal using square wave voltammetry (SWV). All experimental parameters impacting sensor response are examined in order to improve hybridization efficacy, and the electrochemical biosensor's performance. The limit of detection (LOD) for the A. baumannii gene sequence was calculated and found to be 1.93 nM. Three different non-complementary DNA sequences were used to evaluate the assay selectivity, but no interference effect was obtained. Additionally, the potential applicability of the biosensor to real samples was tested in artificial serum media. The suggested electrochemical test procedure is simple, approachable, and quick, making it a convenient approach for the screening of DNA sequence.

Novel Determination of the Influence of Idarubicin upon DNA Chain Structure Using an Electrochemical DNA Biosensor by Voltammetry

Two sequences of DNA (single-strand DNA (ssDNA) and double-strand DNA (dsDNA)) modified disposable electrodes were designed to investigate the effect of antitumor agent drug idarubicine (IDA) on the DNA chain structure. The effect of IDA on DNA structure was analyzed by square wave voltammetry (SWV) depending on not only the guanine signal but also IDA oxidation response. The present study included the electrochemical investigation of IDA and the investigation of the biomolecular interaction between IDA and DNA. IDA was detected in buffer and urine using disposable pencil graphite electrodes (PGE) with SWV and cyclic voltammetry (CV)). The detection limit (LOD) of IDA in urine samples was 0.089 µg mL−1 with SWV under optimum conditions. For the biomolecular interaction of IDA and DNA, all electrochemical conditions, such as the concentration of DNA, concentration of IDA, interaction phase (at electrode surface/in solution phase), the interaction pH, and the interaction time were optimized. IDA interacted biomolecularly with DNA at the electrode surface and in solution phase using two methods. There is no previous electrochemical study performed on the interaction of IDA with ssDNA. Hence, the effect of IDA on both ssDNA and dsDNA was presented for the first time.

Disposable nanosensor for the electrochemical determination of the interaction between DNA, and a mycotoxin, patulin

Silicon dioxide nanoparticles were synthesized and disposable screen-printed electrodes were modified with these nanoparticles to electrochemically detect the interaction between DNA and patulin, a mycotoxin. Firstly, the synthesized silicon dioxide nanoparticles were chemically characterized by X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). Microscopic characterization of the nanoparticles was performed by Transmission Electron Microscopy (TEM) and Energy-dispersive X-ray spectroscopy (EDX). The surface of the silicon dioxide nanoparticle-modified screen-printed electrode was characterized by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). SiNP modification resulted in a 2-fold increase in surface area and a 2.3-fold enhancement in the signal. The detection limit (LOD) for the electrochemical patulin determination was calculated as 1.15 µg/mL, and the linear concentration range was found to be 3.2–20 µg/mL. The mode of interaction between patulin and dsDNA was determined through a molecular docking study. After the interaction between patulin and dsDNA, approximately 86 % and 23 % decreases were observed in patulin and guanine oxidation signals, respectively. The S % value for patulin was calculated by utilizing the decrease in the guanine signal after the interaction.

Copper enhanced guanine electrochemical signal for nucleic acids detection in municipal tertiary wastewater

An electroanalytical method is developed for guanine detection based on its electrochemical oxidation on a clay-modified carbon paste electrode (clay-CPE). The electrochemical guanine signal is found to be significantly enhanced upon its complexation with Cu2+ ions. Cu2+-guanine complex formation is studied using UV–Vis spectroscopy and electrochemical pulse voltammetry at different ratios, with 1:2 Cu2+:guanine found to be the optimal stoichiometry. The clay modifier and the electrode are fully characterized using electron microscopy, Fourier-transform infrared, X-ray photoelectron and X-ray fluorescence spectroscopies, and X-ray diffractometry. The analytical method is fully optimized regarding the electrolyte, technique, and electrochemical parameters. A calibration curve is built obtaining a linear range of 0.1–45 µM, a limit of detection of 0.16 µM, a limit of quantification of 0.54 µM, and a sensitivity of 1.1 µA/µM, which are among the best reported so far and achieved with an environmentally friendly and low-cost method. Our system is very selective with minimal interference in the presence of interferents with concentrations as high as 100× that of guanine. The Cu2+-mediated clay-CPE-based analytical method is applied for the detection of nucleic acid in real-life wastewater, which is critical to achieving efficient wastewater treatment. This demonstrates the applicability of our method for environmental purposes and opens the door for other applications as well, such as diagnostics.

Electrochemical detection of Oxaliplatin induced DNA damage in G-quadruplex structures

Oxaliplatin (OXP) is a platinum-based chemotherapeutic agent that induces DNA damage by forming intra- and interstrand crosslinks, mainly at the N7s of adenine (A) and guanine (G) bases. In addition to double-stranded DNA, G-rich G-quadruplex (G4)-forming sequences can also be targeted by OXP. However, high doses of OXP can lead to drug resistance and cause serious adverse effects during treatment. To better understand the targeting of G4 structures by OXP, their interactions as well as the molecular mechanisms underlying OXP resistance and adverse effects, there is a need for a rapid, quantitative, and cost-effective method to detect OXP and the damage it causes. In this study, we successfully fabricated a graphite electrode biosensor modified with gold nanoparticles (AuNPs) to investigate the interactions between OXP and the G4-forming promoter region (Pu22) of Vascular endothelial growth factor (VEGF). The overexpression of VEGF is known to be associated with tumor progression and the stabilization of VEGF G4 by small molecules is shown to suppresses VEGF transcription in different cancer cell lines. Differential pulse voltammetry (DPV) was used to investigate the interactions between OXP and Pu22-G4 DNA by monitoring the decrease in the oxidation signal of guanine with increasing OXP concentration. Under the optimized conditions (37 °C, 1:2 v/v AuNPs/water as electrode surface modifier, and 180 min incubation time) the developed probe showed a linear dynamic range of 1.0–10.0 μM with a detection limit of 0.88 μM and limit of quantification of 2.92 μM. Fluorescence spectroscopy was also used to support the electrochemical studies. We observed a decrease in the fluorescence emission of Thioflavin T in the presence of Pu22 upon addition of OXP. To our knowledge, this is the first electrochemical sensor developed to study OXP-induced damage to G4 DNA structures. Our findings provide new insights into the interactions between VEGF G4 and OXP, which could aid in targeting VEGF G4 structures and the development of new strategies to overcome OXP resistance.

A nanoscale electrochemical guanine DNA-biosensor based on a flower-like nanocomposite of Tb-doped ZnO for the sensitive determination of pemetrexed.

Pemetrexed is an antineoplastic drug used in chemotherapeutic treatments, especially in malignant mesothelioma and non-small cell lung carcinoma, but can also cause a variety of complications, like stomach pain, nausea, burning, vomiting, numbness, and tingling, emphasizing the need for an approach to quantify the drug in biological matrices. Herein, a DNA-based biosensor was introduced for pemetrexed determination. A hydrothermal approach was used for synthesizing flower-like nanoparticles (NPs) of zinc oxide (ZnO) doped with Tb (FL-NP Tb3+/ZnO). Moreover, energy dispersive X-ray (EDX), field-emission scanning electron microscopy (FESEM), zeta potential, Brunauer-Emmett-Teller (BET), and X-ray diffraction (XRD) analyses were used for characterizing the as-prepared nanocomposite. According to the impedance analysis, FL-NP Tb3+/ZnO was accompanied by very good electrochemical functions for a simple transfer of electrons. In the case of the immobilization of double-stranded deoxyribonucleic acid (ds-DNA) on the FL-NP Tb3+/ZnO and polypyrrole (PP)-modified pencil graphite electrode (ds-DNA/PP/FL-NP Tb3+/ZnO/PGE), a considerable enhancement was found in the electrochemical oxidation of guanine in ds-DNA residue bases. Since there was an interaction between ds-DNA and pemetrexed, the voltammetric current of guanine over the ds-DNA/PP/FL-NP Tb3+/ZnO/PGE declined in the presence of pemetrexed in the electrolytic solution. Moreover, under optimum conditions (25 mg L-1 of ds-DNA and 10 min incubation time, in acetate buffer at 25 °C), a linear decrease in the guanine signal was observed on the ds-DNA/PP/FL-NP Tb3+/ZnO/PGE as the pemetrexed concentration increased in the range from 0.001 μM to 175.0 μM with a limit of detection of 0.17 nM. Finally, the new DNA-based biosensor was successfully used for determining pemetrexed in real samples, indicating its application potential.

Genoprotective effect of cornelian cherry (Cornus mas L.) phytochemicals, electrochemical and ab initio interaction study.

Cornelian cherry (Cornus mas L.) has broad and multidimensional potential in preventing civilisational diseases. Part of these diseases results from DNA oxidative mutations. Thus, the paper aimed to predict how phenolics present in C. mas may interact with dsDNA in ab initio experiment and to check the effect of different cornelian cherry extracts on DNA structure and DNA oxidation. A special research model was designed using biosensor with a carbonpaste electrode. We resulted in various effects observed for phenolics and the extracts. Flavonoids, but of vitexin interacted with declining energy of the DNA models and liability of DNA oxidation. However, for 8-oxoguaniosine the trend was the opposite. Among the evaluated extracts, water-ethanolic extracts caused decline in adenine and guanine signals after dsDNA exposition on the extract. Principal component analysis showed that alcoholic extracts of cv. Szafer and Słowianin, which were rich in apigenin and kaempferol exhibit mild genoprotective effect.

An electrochemical assay for sensitive detection of Acinetobacter baumannii gene

A new genosensor, which allows sensitive and selective detection of Acinetobacter baumannii gene sequence was developed herein. In this assay, capture probe of Acinetobacter baumannii was immobilized on the surface of chitosan modified single-use pencil graphite electrodes (c-PGEs) to obtain Acinetobacter baumannii genosensor. Then, Acinetobacter baumannii target DNA sequence was recognized after solid-state hybridization on c-PGE genosensor by measuring guanine signal via differential pulse voltammetry (DPV). In order to improve hybridization efficiency, experimental parameters affecting all assay steps are studied and the analytical performance of the genosensor was tested. The low limit of detection (LOD) for Acinetobacter baumannii target DNA sequence was obtained as 1.86 nM with developed genosensor. The selectivity of the proposed assay was then tested in the presence of 1-base mismatch, or two different type of non-complementary sequences and no interference effect was observed. The proposed electrochemical assay protocol is easy, convenient, and rapid which can be a decent alternative to existing methods.

Determination of Anti‐Parkinson Drug Pramipexole Using a Label‐free Biosensor and Evaluation of its Interaction with ds‐DNA

AbstractIn this study, we fabricated an effective and sensitive DNA biosensor based on flower‐like Pt/NiCo2O4 modified carbon paste electrode (FL‐Pt/NiCo2O4/CPE) for detection of pramipexole (PPX). Spectrophotometry, differential pulse voltammetry (DPV) and docking methods were employed to evaluate the interaction of DNA‐PPX. Moreover, the DPV technique was chosen to monitor the electrochemical response of guanine on the DNA biosensor. The relationship between the concentration of PPX and the oxidation signal of guanine was linear in the range of 0.4 to 310.0 μM and a limit of detection (LOD) of 0.09 μM was calculated.

Characterization of graphite-epoxy composite electrodes for free electrochemical detection of adenine and guanine in DNA

Graphite-epoxy composites (GECs) are alternative construction materials for electro­chemical sensors. For these materials, the electron transfer rate constant of some redox reaction depends additionally on the stoichiometric relationship between the insulating and conducting phases of the composite. In this work, the influence of dif­fe­rent ratios of araldite/hardener/graphite on the electrochemical properties of GEC electrodes is evaluated for the simultaneous determination of adenine and guanine in the single chain DNA, using the square wave voltammetry technique. Six GEC electro­des were prepared with different ratios of components, and electrochemically charac­terized by cyclic voltammetry in the presence of ferri/ferrocyanide redox couple as a redox probe. GEC electrodes that showed the best electrochemical responses of redox probe were characterized by thermogravimetric analysis (TGA) and used for the simul­taneous determination of free adenine and guanine in a solution, and DNA oligonu­cle­otides. The best results were obtained for GEC electrodes containing twice higher volu­me of araldite resin with respect to the hardener. TGA analysis revealed presence of 15-26 % of resin for these GEC electrodes. The obtained results revealed potential appl­ication of these GEC electrodes as DNA sensors based on the oxidation signal of guanine.

Total antioxidant capacity investigation of electrochemically deposited atractylodes macrocephala traditional medicine

Electrochemically deposited sensors and DNA biosensors have been widely used in the food industry, and various other fields due to their high sensitivity, fast response, easy operation, no pollution, and low price. A rare earth electrochemically deposited gadolinium ferricyanide thin film modified glassy carbon electrode, and the investigation of electrocatalytic oxidation of guanine by GaHCF/GCE is reported. We deposited electrochemically a rare earth terbium ferricyanide thin film modified glassy carbon electrode. OH was investigated through various characteristics such as capacitance–voltage, Differential Pulse Voltammetric and many more by the comparison of catalytic oxidation signal of guanine with ·OH in Fenton reaction.

Doxorubicin Anticancer Drug Monitoring by ds-DNA-Based Electrochemical Biosensor in Clinical Samples.

In this research, glassy carbon electrode (GCE) amplified with single-wall carbon nanotubes (SWCNTs) and ds-DNA was fabricated and utilized for voltammetric sensing of doxorubicin with a low detection limit. In this technique, the reduction in guanine signal of ds-DNA in the presence of doxorubicin (DOX) was chosen as an analytical factor. The molecular docking study revealed that the doxorubicin drug interacted with DNA through intercalation mode, which was in agreement with obtained experimental results. The DOX detection performance of ds-DNA/SWCNTs/GCE was assessed at a concentration range of 1.0 nM–20.0 µM. The detection limit was found to be 0.6 nM that was comparable and even better (in many cases) than that of previous electrochemical reported sensors. In the final step, the ds-DNA/SWCNTs/GCE showed powerful ability for determination of the DOX in injection samples with acceptable recovery data.

Electrochemical investigation of the interaction of 2,4-D and double stranded DNA using pencil graphite electrodes.

2,4-dichlorophenoxyacetic acid (2,4-D) is an auxinic herbicide used to control broadleaf weeds. It is also a threatening factor for not only aquatic life but also human health due to its genotoxicity and endocrine disruptive property. Herein, the interaction between 2,4-D and double stranded DNA was investigated by using single-use pencil graphite electrodes (PGE) in combination with electrochemical techniques. The detection mechanism was based on the monitoring of the changes at the guanine oxidation signal obtained before/after surface-confined interaction of 2,4-D and DNA at the surface of PGE. The electrochemical characterization of the interaction was studied by using microscopic and electrochemical techniques. The response obtained by interaction in the presence of another herbicide, glyphosate, which is widely used with 2,4-D for weed control, was compared to the one occurred in the presence of 2,4-D. Electrochemical monitoring of the interaction between the herbicide whose active molecule was 2,4-D and DNA was also investigated. The detection (LOD) and quantification limits (LOQ) for 2,4-D and the herbicide could be obtained in the linear concentration ranges of 30–70 µg/mL and 10–30 µg/mL, respectively and LOD and LOQ values were found to be 2.85 and 9.50 µg/mL for both 2,4-D and the herbicide. The sensitivity of the biosensor was calculated as 0.087 µA.mL / µg.cm2 .This is the first study in literature by means of not only voltammetric detection of 2,4-D and DNA interaction but also the herbicide-DNA interaction at the surface of PGE based on the changes at the guanine signal.

Cobalt Phthalocyanine-Ionic Liquid Composite Modified Electrodes for the Voltammetric Detection of DNA Hybridization Related to Hepatitis B Virus.

In this study, cobalt phthalocyanine (CoPc) and ionic liquid (IL) modified pencil graphite electrodes (PGEs) were designed and implemented to detect sequence-selective DNA hybridization related to the Hepatitis B virus (HBV). The surface characterization of CoPc-IL-PGEs was investigated by scanning electron microscopy (SEM), and the electrochemical behavior of electrodes were studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The voltammetric detection of hybridization was investigated by evaluating the guanine oxidation signal, measured by differential pulse voltammetry (DPV) technique. The implementation of our biosensor to serum samples was also examined using fetal bovine serum (FBS). The detection limit was established as 0.19 µg/mL in phosphate buffer solution (PBS) (pH 7.40) and 2.48 µg/mL in FBS medium. The selectivity of our assay regarding HBV DNA hybridization in FBS medium was tested in the presence of other DNA sequences. With this aim, the hybridization of DNA probe with non-complementary (NC) or mismatched DNA sequence (MM), or in the presence of mixture samples containing DNA target NC (1:1) or DNA target MM (1:1), was studied based on the changes in guanine signal.

Development of an Electrochemical Sensor Using Pencil Graphite Electrode for Monitoring UV-Induced DNA Damage

This laboratory experiment introduces the fundamentals of electrochemical techniques to the undergraduate students by developing a simple and cost-effective miniaturized electrochemical setup for detecting UV-induced DNA damage. This is an imperative experiment, as it provides students first-hand experience with electrochemical techniques while reinforcing lecture material on the biosensing applications. In this experiment, a simple and daily use material such as an ordinary pencil lead acts as a platform for an electrochemical DNA sensor. A three-electrode cell setup is utilized to monitor UV-induced DNA damage. Students will test the hypothesis about UV-induced DNA damage by measuring the redox signal of guanine under various experimental conditions. The simple, fast, and inexpensive setup allows students to examine the factors that would influence the electrochemical signals. This experimental work provides an opportunity for students to learn how to design a simple electrochemical experiment for research purposes as well as handling the biological samples. Proposing a hypothesis and testing it by designing an experiment are the experiences that will be gained by the students while learning about the optimization and validation of an analytical technique.

Electrochemical detection of interaction between daunorubicin and DNA by hybrid nanoflowers modified graphite electrodes

In this study, two types of hybrid nanoflowers (NFs) modified disposable electrodes were developed to investigate the electrochemical behavior of anticancer drug-DNA interaction. Biocompatible hybrid NFs were synthesized by amino acids (L-glutamic acid and l-cysteine) via a simple, rapid and cost-effective methods. Structural characterizations of the synthesized hybrid NFs were performed with Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), while morphological characterizations were performed using scanning electron microscopy (SEM) and energy diffuser X-ray (EDX) spectroscopy techniques. As the sensing platform in electrochemical studies, pencil graphite electrode (PGE) has been used because of its advantages such as low cost, easy-to-handle, portable and disposable. After PGEs modified with NFs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques, differential pulse voltammetry (DPV) technique was used in the determination of calf thymus double stranded DNA (ctdsDNA) and also daunorubicin (DNR) as well as DNA-DNR interaction. The detection limits as a result of ctdsDNA determination were found to be 0.93 μg/mL by using l-cysteine NFs modified PGE (c-NFs-PGE) and 2.37 μg/mL by using l-glutamic acid modified PGE (ga-NFs-PGE). The detection limits obtained for the determination of DNR were found as 2.93 μM and 2.06 μM with c-NFs-PGE and ga-NFs-PGE, respectively. The optimum interaction time between DNR and ctdsDNA was determined by c-NFs-PGE, which showed higher sensitivity performance against oxidation of guanine signals.

Two-signal electrochemical detection system for evaluation viability of Staphylococcus aureus

Establishment of new method for evaluation microbial viability has become an urgent need in the fields of biology, medicine, environment and so on. In this paper, two electrochemical signals of Staphylococcus aureus (S. aureus) at + 0.693 and + 0.973 V vs. Ag/AgCl (sat. KCl) were detected on the multi-walled carbon nanotube modified glassy carbon electrode (MWCNTs/GCE), and attributed to the oxidation of guanine and adenine secreted by S. aureus. For the first time, bacterial viability was evaluated from the perspective of proliferation and purine metabolism. Compared with the plate counting method, the electrochemical signals of guanine and adenine showed an earlier change of viability when S. aureus entered stationary from logarithmic phase and apoptotic from stationary phase during the growth process of S. aureus. There were good linear relationships between electrochemical signals of guanine and adenine and the number of S. aureus cells in different growth phases, but there were different detection thresholds. At the logarithmic phase, S. aureus had stronger viability and ability to metabolize purines, which resulted in a lower detection threshold. Both electrochemical signals of bacteria could well reflect the inhibition of levofloxacin on S. aureus viability, and the guanine signal peak was closer to the result of plate counting method.

The Genoprotective Role of Naringin.

Since ancient times, fruits and edible plants have played a special role in the human diet for enhancing health and maintaining youthfulness. The aim of our work was to determine the interactions between naringin, a natural ingredient of grapefruits, and DNA using an electrochemical biosensor. Electrochemical methods allow analyzing the damages occurring in the structure of nucleic acids and their interactions with xenobiotics. Our study showed that the changes in the location of electrochemical signals and their intensity resulted from the structural alterations in DNA. The signal of adenine was affected at lower concentrations of naringin, but the signal of guanine was unaffected in the same condition. The dynamics of changes occurring in the peak height and surface of adenine related to naringin concentration was also significantly lower. The complete binding of all adenine bases present in the tested double-stranded DNA solution was observed at naringin concentrations ranging from 8.5 to 10.0 µM. At larger concentrations, this active compound exerted an oxidizing effect on DNA. However, the critical concentrations of naringin were found to be more than twice as high as the dose absorbable in an average human (4 µM). The results of our work might be helpful in the construction of electrochemical sensors for testing the content of polyphenols and would allow determining their genoprotective functionality.

ELECTROCHEMICAL BIOSENSOR FOR BRCA1 GENE AND TAMOXIFEN INTERACTION

The electrochemical nanobiosensor was designed for the determination of specific DNA sequences related to breast cancer 1 (BRCA1) gene and interaction between Anticancer Drug Tamoxifen (TAM) and related DNA sequences by using pencil graphite electrode (PGE), bare and multi-walled carbon nanotube (MWCNT) contained screen printed carbon electrodes (SPEs) for the first time. Here, biomolecular interaction between TAM and DNA was investigated differential pulse voltammetry (DPV) based on not only guanine signal but also TAM oxidation response. It was obtained that the guanine signal at about +1.00V obtained from probe DNA or hybrid DNA shows a remerkable increase after the interaction with TAM. Additionally, it was found that TAM interact with guanine bases and TAM signal which is near the guanine oxidation area also increase after the interaction with DNA. Consequently, the prepared biosensor offer suitable platform for the analysis of DNA hybridization and TAM-DNA interaction sensitively.

Ionic Liquid Modified Single‐use Electrode Developed for Voltammetric Detection of miRNA‐34a and its Application to Real Samples

AbstractThe ionic liquid (IL) modified chemically activated (CA) pencil graphite electrodes (PGEs) were developed for label‐free voltammetric detection of miRNA‐34a, and implemented to the real samples. Firstly, the electrochemical characterization of unmodified PGE, CA‐PGE, IL‐PGE and IL‐CA‐PGE was performed by cyclic voltammetry (CV) as well as their DNA binding capacity was studied by electrochemical impedance spectroscopy (EIS) technique. The microscopic characterization of the surface of each electrodes was investigated by scanning electron microscopy (SEM). Differential pulse voltammetry (DPV) technique was used for measuring the oxidation signal of guanine in order to perform a label‐free voltammetric monitoring of a full‐match hybridization specific to miRNA‐34a. The selectivity of biosensor was tested against to miRNA‐155, miRNA‐660 as well as to the mismatch sequence of miRNA‐34a. The further selectivity of this proposed biosensor was studied in the mixture of samples containing miRNA‐34a with other miRNAs (1 : 1). The voltammetric detection of miRNA‐34a was also explored in the artificial serum medium as fetal bovine serum (FBS) and also in total RNA samples isolated from HUH‐7 human hepatocellular carcinoma cell line.