A sensitive electrochemical DNA biosensor has been developed for the detection of Buprenorphine (Bu), a narcotic pain reliever. To achieve this, double-stranded DNA (ds-DNA) was immobilized on a pencil graphite electrode that was modified with gold nanoparticles (Au NPs/PGE). The gold nanoparticles enhanced the performance of the DNA biosensor. The constructed ds-DNA/Au NPs/ PGE exhibited a linear detection range spanning from 0.05 to 100 μM with an impressive detection limit of 20 nM for Bu detection. Additionally, the DNA biosensor demonstrated good response in real samples evaluations. Finally, the interaction between carbon and gold atoms with DNA was confirmed through molecular dynamics simulation, while the interaction between DNA and the Bu drug was confirmed through molecular docking method. In conclusion, the electrochemical DNA biosensor presented in this study demonstrates exceptional sensitivity and reliability in the detection of buprenorphine. The incorporation of gold nanoparticles, as well as the use of molecular dynamics simulations and docking methods, contributes to a comprehensive understanding of the interactions involved in this detection process.

UNASSIGNED: In this study, we present an electrochemical sensor for the detection of oxypeucedanin (Oxyp) and prantschimgin (Pra), two natural furanocoumarin derivatives. The determination of the effects of these molecules on DNA is important to be potential drug candidates. Our research focused on exploring the electrochemical behaviour of these compounds and their interaction with DNA.
UNASSIGNED: The electrochemical properties of Oxyp and Pra were systematically analyzed by evaluating their oxidation currents. Changes in the oxidation currents and peak potentials of guanine bases were monitored before and after interaction in the solution phase and at the electrode surface.
UNASSIGNED: The limit of detection (LOD) and limit of quantitation (LOQ) for Oxyp were determined to be 1.3 and 4.3 μg/mL, respectively. For Pra, the LOD and LOQ were found to be 20 and 68 μg/mL, respectively. Stability studies demonstrated that the Oxyp solution retained its oxidation capacity for over a month, whereas the Pra solution retained its oxidation capacity for nearly 120 min. Our findings suggest that Oxyp interacts with dsDNA, potentially through electrostatic interactions, showing promise as a potential drug candidate targeting DNA. On the other hand, the interaction of Pra with dsDNA requires further exploration to fully understand its mode of action.
UNASSIGNED: The electrochemical sensor developed in this study provides a reliable and efficient method for detecting and analysing the interaction of these natural compounds with dsDNA. Our research contributes to advancing the understanding of the interaction between natural furanocoumarins and dsDNA, laying the groundwork for the design and development of novel and effective DNA-targeted drugs.

BACKGROUND: Spectroelectrochemistry (SEC) is a valuable analytical tool providing insights to reaction mechanisms and the structure of species involved in charge transfer reactions. Most of commercial SEC setups are based on platinum working electrodes where the adsorption of species involved in reactions often complicates their analysis.
RESULTS: In this work, we employ an array of pencil graphite rods as an optically transparent working electrode in a custom-made air-tight thin-layer cell suitable for the SEC analysis performed here in acetonitrile as a representative non-aqueous solvent. The functionality of the device was demonstrated by UV-Vis SEC sensing of charge transfer reactions of ruthenium acetylacetonate, ferrocene and ethylviologen dibromide redox probes performed employing the cyclic voltammetry. The SEC response obtained for all three probes confirmed no adsorption and the absence of oxygen in the cell. Furthermore, we have developed and utilized finite element method numerical simulations considering charge transfer reactions coupled with the diffusional mass transport to model the cyclic voltammetric response and the reaction conversion in the thin-layer SEC cell.
CONCLUSIONS: Our work paves the way for easy-to-assemble customized air-tight adsorption-free SEC devices with the manufacturing costs well below those of commercially available platforms. Developed computational approaches have the predictive power for optimizing reaction conditions and the geometry of the SEC cell.

Bisphenol A (BPA) and its substitute bisphenol S (BPS) are desirable materials widely used in manufacturing plastic products but can pose carcinogenic risks to humans. A new conductive iron-based metal-organic framework (Fe-HHTP)-modified pencil graphite electrode (PGE) for electrochemically sensing BPA and BPS was prepared and fully characterized by SEM, TEM, FT-IR, XRD, and XPS. Results showed that the optimal conditions for preparing Fe-HHTP/PGE were a pH of 6.5, a Fe-HHTP concentration of 2 mg·mL-1, a deposition potential of 0 V, and a deposition time of 100 s. The Fe-HHTP/PGE prepared under such conditions harbored a significant electrocatalytic activity with a detection limit of 0.8 nM for BPA and 1.7 nM for BPS (S/N = 3). Correspondingly, the electrochemical response current was linearly correlated to BPA and BPS, ranging from 0.01 to 100 μM. Fe-HHTP/PGE also obtained satisfactory recoveries by 93.8-102.1% and 96.0-101.3% for detecting BPA and BPS in plastic food packaging samples. Our work has provided a novel electrochemical tool to simultaneously detect BPA and BPS in food packaging samples and environmental matrixes.

Ferulic acid (FA), a monohydroxycinnamic acid, is an antioxidant with multiple beneficial effects on human health, presenting also importance in the food and cosmetics industry. Its electrochemical behavior was investigated at the disposable and cost-effective pencil graphite electrode (PGE). Cyclic voltammetry emphasized its pH-dependent, diffusion-controlled oxidation. Using the optimized conditions (HB type PGE, Britton Robinson buffer pH 4.56) differential pulse and square-wave voltammetric techniques were applied for its quantitative determination in the range 4.00 × 10-7-1.00 × 10-3 mol/L FA. The developed methods were employed for the rapid and simple assessment of the FA content from a commercially available powder designed for cosmetic use.

This study reports the electrochemical monitoring and sensing of diphenylamine (DPA), an anti-scald agent on a modified pencil graphite electrode (PGE). DPA is also a potentially toxic environmental pollutant. A polymer of tyrosine synthesized by electrochemical process was utilized for the determination of DPA in real samples. The electrodes were characterized using IR, SEM, EDAX, AFM and EIS analyses. As far as we know, this is first time reporting the utilization of modified PGE via green approach for the monitoring of DPA. A dynamic linear range of 1.00-117.11 µM with a lower detection limit (LOD) of 0.7050 µM was showed by this sensor for the electrochemical quantification of DPA. The electrochemical oxidation of DPA on the modified sensor followed a mixed adsorption -diffusion controlled kinetics. The sensor also showed good anti-interference property for the determination of DPA in real samples. Furthermore, the developed sensor was applied for the selective sensing of DPA from real apple extracts with good recovery. The real sample analysis was validated with standard spectrophotometric method.

In the present work, a novel electrochemical DNA sensor was designed to detect L. monocytogenes. Two different gene fragments were selected for the sensor design. One is a 702 bp long fragment of the hlyA gene, encoding the synthesis of listeriolysin O toxin, which is unique only to pathogenic strains of L. monocytogenes and is essential for pathogenicity. The other is a 209 bp long fragment of the 16 S RNA gene found in all species of the Listeria genus. As the working electrode, the pencil graphite electrode was modified in various ways (activated or covered with polypyrrole), and six different combinations were constituted using three types of the modified working electrode and two different gene fragments. The developed system is based on differential pulse voltammetric transduction of guanine oxidation after hybridization between the selected gene fragment (38 µg/mL) and the selected fragment-specific inosine-modified probe (1.8 µmol/L) immobilized on a pencil graphite electrode surface. The comparison of all combinations demonstrates that the best results are obtained with the combination formed from a polypyrrole-coated pencil graphite electrode (prepared at 2 scans) and 702 bp fragment of the hlyA gene. The analysis time is less than 1 hour, and the necessary DNA concentrations for the analysis have been determined as 8.2 × 10-11 M DNA and 2.7 × 10-10 M DNA respectively, for the hlyA gene and 16 S RNA gene.

OBJECTIVE: The anticoagulant drug edoxaban has a blood thinning mechanism of action. In this study, a pencil graphite electrode was electrochemically activated at + 1.4 V for 60 s. in a Britton-Robinson (pH 9.0) supporting electrolyte solution.
METHODS: A simple, fast, and sensitive electrochemical procedure was developed using cyclic voltammetry and square wave voltammetry techniques. It was observed that edoxaban gave a good oxidation signal with cyclic voltammetry technique at a potential of + 0.98 V (vs. Ag/AgCl).
RESULTS: This procedure showed a linear response in a Britton-Robinson (pH 9.0) media within the concentration range of 0.2-1.8 µM and limit of detection (LOD) and the limit of quantification (LOQ) values were determined to be 0.073 μM (0.133 μg mL-1) and 0.243 μM (0.443 μg mL-1), respectively.
CONCLUSIONS: The method developed in this study was successfully applied to drug and urine samples. The developed voltammetric method was highly selective and gave satisfactory recovery results in urine and pharmaceutical samples. The results of the voltammetric method were compared with the spectroscopic method and it was determined that the results were compatible.

Silver nanoparticles (AgNPs) were synthesized through an environmentally friendly method with tea extract as a reduction agent. By immobilizing them on the surface of a low-cost pencil graphite electrode (PGE) with the aid of a simple and well-controlled in-situ electropolymerization method, a novel nanosensing interface for nitrite was constructed. The film-modified PGE showed good electrocatalytic effects on the oxidation of nitrite and was characterized through scanning electron microscopy, X-ray photoelectron spectroscopy, and electrochemical techniques. Characterization results clearly show that the successful modification of AgNPs improved the surface area and conductivity of PGEs, which is beneficial to the high sensitivity and short response time of the nitrite sensor. Under the optimal detection conditions, the oxidation peak current of nitrite had a good linear relationship with its concentration in the range of 0.02-1160 μmol/L with a detection limit of 4 nmol/L and a response time of 2 s. Moreover, the sensor had high sensitivity, a wide linear range, a good anti-interference capability, and stability and reproducibility. Additionally, it can be used for the determination of nitrite in food.

Pencil graphite electrode (PGE) is an alternative, commercially available, ready-to-use, screen-printed electrode for a wide range of electroanalytical applications. Due to the complex-matrix composition and unpredictable electro-inactive nature of PGE in its native form, a surface pre-treatment/activation procedure is highly preferred for using it as an electroactive working electrode for electroanalytical applications. In this article, we review various surface pre-treatment and modification procedures adopted in the literature with respect to the sensitive and selective detection of dopamine as a model system. Specific generation of the carbon-oxygen functional group, along with partial surface exfoliation of PGE, has been referred to as a key step for the activation. Based on the Scopus® index, the literature collection was searched with the keywords \"pencil and dopamine\". The obtained data were segregated into three main headings as: (i) electrochemically pre-treated PGE; (ii) polymer-modified PGEs; and (iii) metal and metal nanocomposite-modified PGE. This critical review covers various surface activation procedures adopted for the activation for PGE suitable for dopamine electroanalytical application.