A Graphene Oxide-DNA Electrochemical Sensor Based on Glassy Carbon Electrode for Sensitive Determination of Methotrexate

Magnetic separation-assisted DNAzyme walker-based nanosensor for point-of-care therapeutic drug monitoring of methotrexate

Methotrexate (MTX) is a widely used antimetabolite drug, mainly used in the treatment of a variety of cancer. Given the low therapeutic index and significant individual variability of MTX, it was critical to perform therapeutic drug monitoring (TDM) to minimize the side effects. Here, we designed a rapid and sensitive fluorescence/colorimetric assay for the detection of MTX in diluted human serum. After the aptamer binds specifically to MTX, the Walking strand cleaves the Hairpin strand and releases a large amount of fluorescent signal, and the color of the gold nanoparticles changes after the addition of sodium chloride. The change of color could be visualized by eyes to achieve point-of-care TDM of MTX. The quantitative detection of MTX concentration is carried out through the collection of fluorescent signals or absorptions. The fluorescence method can detect MTX in the range of 0.05-1000 μM with the detection limit of 0.0243 μM, meanwhile, the colorimetric method can detect MTX in the range of 0.01-100 μM with the detection limit of 0.0097 μM. The magnetic separation-assisted DNAzyme walker-based nanosensor exhibited good sensitivity, selectivity and stability for detecting MTX in serum and achieve point-of-care methods of TDM of MTX and the nanocarriers has demonstrated significant potential for clinical application.

Electrochemistry as a Powerful Tool for Investigations of Antineoplastic Agents: A Comprehensive Review

Cancer is most frequently treated with antineoplastic agents (ANAs) that are hazardous to patients undergoing chemotherapy and the healthcare workers who handle ANAs in the course of their duties. All aspects related to hazardous oncological drugs illustrate that the monitoring of ANAs is essential to minimize the risks associated with these drugs. Among all analytical techniques used to test ANAs, electrochemistry holds an important position. This review, for the first time, comprehensively describes the progress done in electrochemistry of ANAs by means of a variety of bare or modified (bio)sensors over the last four decades (in the period of 1982-2021). Attention is paid not only to the development of electrochemical sensing protocols of ANAs in various biological, environmental, and pharmaceutical matrices but also to achievements of electrochemical techniques in the examination of the interactions of ANAs with deoxyribonucleic acid (DNA), carcinogenic cells, biomimetic membranes, peptides, and enzymes. Other aspects, including the enantiopurity studies, differentiation between single-stranded and double-stranded DNA without using any label or tag, studies on ANAs degradation, and their pharmacokinetics, by means of electrochemical techniques are also commented. Finally, concluding remarks that underline the existence of a significant niche for the basic electrochemical research that should be filled in the future are presented.

Synthesis of poly (L-cysteine)/g-C3N4 modified glassy carbon electrodes for electrochemical detection of methotrexate as a medicine for treatment of breast cancer in pharmaceutical fluid samples

Analyzing the levels of anticancer medications in biological samples and body fluids reveals important details on the course and effects of chemotherapy. p (L-Cys)/graphitic-carbon nitride (g-C₃N₄)/GCE, a modified glassy carbon electrode, was created for the current study's electrochemical detection of methotrexate (MTX), a drug used to treat breast cancer, in pharmaceutical fluid samples. l-Cysteine was electro-polymerized on the surface of the g-C₃N₄/GCE after the g-C₃N₄ was first modified to prepare the p (L-Cys)/g-C₃N₄/GCE. Analyses of morphology and structure showed that well-crystalline p (L-Cys) on g-C₃N₄/GCE was successfully electropolymerized. Studying the electrochemical characteristics of p (L-Cys)/g-C₃N₄/GCE using CV and DPV techniques revealed a synergistic impact between g-C₃N₄ and l-cysteine that improved the stability and selectivity of the electrochemical oxidation of MTX while enhancing the electrochemical signal. Results showed that 7.5-780 μM was the linear range, and that 0.11841 μA/μM and 6 nM, respectively, were the sensitivity and limit of detection. The applicability of the suggested sensors was assessed using real pharmaceutical preparations, and the results showed that p (L-Cys)/g-C₃N₄/GCE had a high degree of precision. Five breast cancer patients who volunteered and provided prepared blood serum samples between the ages of 35 and 50 were used to examine the validity and accuracy of the proposed sensor in the current work for the determination of MTX. The results showed good recovery values (greater than 97.20%), appropriate accuracy (RSD less than 5.11%), and good agreement between the ELISA and DPV analysis results. These findings showed that p (L-Cys)/g-C₃N₄/GCE can be applied as a trustworthy MTX sensor for MTX level monitoring in blood samples and pharmaceutical samples.

Electrochemical Biosensors for Whole Blood Analysis: Recent Progress, Challenges, and Future Perspectives

Whole blood, as one of the most significant biological fluids, provides critical information for health management and disease monitoring. Over the past 10 years, advances in nanotechnology, microfluidics, and biomarker research have spurred the development of powerful miniaturized diagnostic systems for whole blood testing toward the goal of disease monitoring and treatment. Among the techniques employed for whole-blood diagnostics, electrochemical biosensors, as known to be rapid, sensitive, capable of miniaturization, reagentless and washing free, become a class of emerging technology to achieve the target detection specifically and directly in complex media, e.g., whole blood or even in the living body. Here we are aiming to provide a comprehensive review to summarize advances over the past decade in the development of electrochemical sensors for whole blood analysis. Further, we address the remaining challenges and opportunities to integrate electrochemical sensing platforms.

Electrochemical DNA sensors for drug determination

In this review, recent achievements in the development of the DNA biosensors developed for the drug determination have been presented with particular emphasis to the main principles of their assembling and signal measurement approaches. The design of the DNA sensors is considered with characterization of auxiliary components and their necessity for the biosensor operation. Carbon nanomaterials, metals and their complexes as well as electropolymerized polymers are briefly described in the assembly of DNA sensors. The performance of the DNA sensors is summarized within 2017-2022 for various drugs and factors influencing the sensitivity and selectivity of the response are discussed. Special attention is paid to the mechanism of the signal generation and possible drawbacks in the analysis of real samples.

DNA-Based Electrodes and Computational Approaches on the Intercalation Study of Antitumoral Drugs

The binding between anticancer drugs and double-stranded DNA (dsDNA) is a key issue to understand their mechanism of action, and many chemical methods have been explored on this task. Molecular docking techniques successfully predict the affinity of small molecules into the DNA binding sites. In turn, various DNA-targeted drugs are electroactive; in this regard, their electrochemical behavior may change according to the nature and strength of interaction with DNA. A carbon paste electrode (CPE) modified with calf thymus ds-DNA (CPDE) and computational methods were used to evaluate the drug–DNA intercalation of doxorubicin (DOX), daunorubicin (DAU), idarubicin (IDA), dacarbazine (DAR), mitoxantrone (MIT), and methotrexate (MTX), aiming to evaluate eventual correlations. CPE and CPDE were immersed in pH 7 0.1 mM solutions of each drug with different incubation times. As expected, the CPDE response for all DNA-targeted drugs was higher than that of CPE, evidencing the drug–DNA interaction. A peak current increase of up to 10-fold was observed; the lowest increase was seen for MTX, and the highest increase for MIT. Although this increase in the sensitivity is certainly tied to preconcentration effects of DNA, the data did not agree entirely with docking studies, evidencing the participation of other factors, such as viscosity, interfacial electrostatic interactions, and coefficient of diffusion.

Graphene Oxide Nanoparticles Modified Paper Electrode as a Biosensing Platform for Detection of the htrA Gene of O. tsutsugamushi

The unique structural and electrochemical properties of graphene oxide (GO) make it an ideal material for the fabrication of biosensing devices. Therefore, in the present study, graphene oxide nanoparticles modified paper electrodes were used as a low-cost matrix for the development of an amperometric DNA sensor. The graphene oxide was synthesized using the modified hummers method and drop cast on a screen-printed paper electrode (SPPE) to enhance its electrochemical properties. Further, the GO/SPPE electrode was modified with a 5′NH2 labeled ssDNA probe specific to the htrA gene of Orientia tsutsugamushi using carbodiimide cross-linking chemistry. The synthesized GO was characterized using UV-Vis, FTIR, and XRD. The layer-by-layer modification of the paper electrode was monitored via FE-SEM, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The sensor response after hybridization with single-stranded genomic DNA (ssGDNA) of O. tsutsugamushi was recorded using differential pulse voltammetry (DPV). Methylene blue (1 mM in PBS buffer, pH 7.2) was used as a hybridization indicator and [Fe(CN)₆]^−3/−4 (2.5 mM in PBS buffer, pH 7.2) as a redox probe during electrochemical measurements. The developed DNA sensor shows excellent sensitivity (1228.4 µA/cm²/ng) and LOD (20 pg/µL) for detection of O. tsutsugamushi GDNA using differential pulse voltammetry (DPV).

Label-Free Bioelectrochemical Methods for Evaluation of Anticancer Drug Effects at a Molecular Level

Cancer is a multifactorial family of diseases that is still a leading cause of death worldwide. More than 100 different types of cancer affecting over 60 human organs are known. Chemotherapy plays a central role for treating cancer. The development of new anticancer drugs or new uses for existing drugs is an exciting and increasing research area. This is particularly important since drug resistance and side effects can limit the efficacy of the chemotherapy. Thus, there is a need for multiplexed, cost-effective, rapid, and novel screening methods that can help to elucidate the mechanism of the action of anticancer drugs and the identification of novel drug candidates. This review focuses on different label-free bioelectrochemical approaches, in particular, impedance-based methods, the solid supported membranes technique, and the DNA-based electrochemical sensor, that can be used to evaluate the effects of anticancer drugs on nucleic acids, membrane transporters, and living cells. Some relevant examples of anticancer drug interactions are presented which demonstrate the usefulness of such methods for the characterization of the mechanism of action of anticancer drugs that are targeted against various biomolecules.

DNA Carbon-Nanodots based Electrochemical Biosensor for Detection of Mutagenic Nitrosamines

Mutagenic and Carcinogenic substances are a threat to any living organism, and its detection is of paramount importance. In this work, we fabricate for the first time a DNA-carbon dots based electrochemical biosensor for sensitive and selective detection of mutagenic nitrosamines like N-nitrosodimethylamine (NDMA) and N-nitrosodiethanolamine (NDEA). At first, on the glassy carbon electrode (GCE), chitosan carbon dot was deposited, then, DNA was electro-statically immobilizing on the surface of carbon dots to fabricate the sensing electrode (DNA/chiCD/GCE modified electrode). In the presence of NDMA and NDEA, in differential pulse voltammetry technique, the absolute peak current increases, and thus it can detect NDMA and NDEA. The system DNA/chiCD/GCE modified electrode is highly selective and sensitive toward NDMA and NDEA. The detection limit was determined to be 9.9 × 10^-9 M and 9.6 × 10^-9 M, respectively. The possible reason for DNA/chiCD/GCE modified electrode showing such electrochemical selectivity toward nitrosamines is investigated and discussed.

Synthesis of bifunctional cabbage flower-like Ho3+/NiO nanostructures as a modifier for simultaneous determination of methotrexate and carbamazepine

Cabbage flower-like Ho³⁺/NiO nanostructure (CFL-Ho³⁺/NiO NSs) with significant electrocatalytic oxidation has been published for the first time. First, structure and morphology of CFL-Ho³⁺/NiO-NSs have been described by XRD, SEM, and EDX methods. Then, CFL-Ho³⁺/NiO-NSs have been applied as a modifier for simultaneous electrochemical detection of methotrexate (MTX) and carbamazepine (CBZ). Functions of the modified electrode have been dealt with through electrochemical impedance spectroscopy (EIS). It has been demonstrated that the electrode response has been linear from 0.001-310.0 μM with a limit of detection of 5.2 nM and 4.5 nM (3 s/m) through DPV for MTX and CBZ. Diffusion coefficient (D) and heterogeneous rate constant (k_h) have been detected for MTX and CBZ oxidation at the surface of the modified electrode. Moreover, CFL-Ho³⁺/NiO-NS/GCE has been employed for determining MTX and CBZ in urine and drug specimens. Outputs showed the analyte acceptable recovery. Therefore, the electrode could be applied to analyze both analytes in drug prescription and clinical laboratories. Graphical abstract Electrochemical sensor based on bifunctional cabbage flower-like Ho³⁺/NiO nanostructures modified glassy carbon electrode for simultaneous detecting methotrexate and carbamazepine was fabricated.

Applications of Graphene and Its Derivatives in Chemical Analysis

In this review, the applications of graphene and its derivatives in the chemical analysis have been described. The properties of graphene materials which are essential for their use in chemical and biochemical analysis are characterized. The materials are used in sensors and biosensors, in electrochemistry, in chromatography and in the sample preparation techniques. Chemical and electrochemical sensors containing graphene materials are useful devices for detecting some chemical and biochemical compounds. Chromatographic columns for HPLC with graphene containing stationary phases may be used for separation of polar and nonpolar components of some specific mixtures. Graphene materials could be successfully employed during sample preparation for analysis with SPE, magnetic SPE, and SPME techniques. HighlightsThe review of the applications of graphene (G) and its derivatives, graphene oxide (GO) and reduced graphene oxide (rGO), in chemical and biochemical analysis is proposed.The electron donor-acceptor and proton donor-acceptor interactions for the graphene based materials - analytes systems and their impact on the analysis results are discussed, particularly:    i) in electrochemistry,ii) in chromatography,iii) in modern sample preparation techniquesiv) in sensors of different types.The essence of the thermal stability and the nomenclature of the graphene based materials in their different applications in chemical systems of different classes was discussed (and suggested).The benefits of using SPME fibers with immobilized graphene materials have been presented in detail.

Ultrasound-induced radicals initiated the formation of inorganic-organic Pr2O3/polystyrene hybrid composite for electro-oxidative determination of chemotherapeutic drug methotrexate

To dates, the facile synthesis of inorganic-coated organic polymer composite has received greater attention in the order of research fields including advanced materials and electrochemical analysis owing to the complementary or synergistic effects. In this context, Pr₂O₃ and Pr₂O₃ coated polystyrene (Pr₂O₃/PS) inorganic-organic colloidal composite were prepared via ultrasound-induced radicals initiated precipitation and dispersion polymerization methods. The synthesized Pr₂O₃/PS composite was systematically studied by FE-SEM, TEM, EDX, FT-IR, XRD, and XPS analysis. This composite modified glassy carbon electrode (Pr₂O₃/PS GCE) was utilized to construct a novel electrochemical sensor for the detection assay of chemotherapy agent methotrexate (MTA). Under optimal condition, the designed sensor showed outstanding performance for MTA trace level detection over the linear concentration range of 0.01-236 µM with a detection limit of 0.8 nM for MTA. Furthermore, the prepared sensor accomplished excellent stability and relevant reproducibility, in addition to reliable practical assay in real human blood serum and urine samples. Besides, the possible MTA sensing mechanism of Pr₂O₃/PS GCE has been deliberated in detail. Our finding suggested that the developed Pr₂O₃/PS composite might be a favorable material for the fabrication of the high-performance electrochemical sensor.

Modern Assay Techniques for Cancer Drugs: Electroanalytical and Liquid Chromatography Methods

In the past decades, patients who have chemotherapy treatment have considerably increased number. At this point, the development of rapid precise, and reliable methods are very important to analyze cancer drugs from their dosage forms, animals or human biological samples. Among all the analytical methods, electrochemical methods hold an important position with their unique properties such as specificity in the biological recognition process, fast response, and their reliability and do not need a pretreatment process. Chromatographic methods are also used in a wide range of analytical applications for the analyses of anticancer drugs. The power of chromatography comes from its ability to separate a mixture of analytes and determination of their concentrations. Chromatographic techniques can mainly be divided into gas, liquid, and supercritical fluid chromatography. In the frame of this information, this review is aimed to provide basic principles of electroanalytical and high-performance liquid chromatography methods for the analysis of cancer drugs. In addition, some selected applications for electrochemistry-related techniques and high-performance liquid chromatography, for the determination of anti-cancer pharmaceuticals published in the last five years are also discussed.

Mussel-inspired functionalization of electrochemically exfoliated graphene: Based on self-polymerization of dopamine and its suppression effect on the fire hazards and smoke toxicity of thermoplastic polyurethane

The suppression effect of graphene in the fire hazards and smoke toxicity of polymer composites has been seriously limited by both mass production and weak interfacial interaction. Though the electrochemical preparation provides an available approach for mass production, exfoliated graphene could not strongly bond with polar polymer chains. Herein, mussel-inspired functionalization of electrochemically exfoliated graphene was successfully processed and added into polar thermoplastic polyurethane matrix (TPU). As confirmed by SEM patterns of fracture surface, functionalized graphene possessing abundant hydroxyl could constitute a forceful chains interaction with TPU. By the incorporation of 2.0 wt % f-GNS, peak heat release rate (pHRR), total heat release (THR), specific extinction area (SEA), as well as smoke produce rate (SPR) of TPU composites were approximately decreased by 59.4%, 27.1%, 31.9%, and 26.7%, respectively. A probable mechanism of fire retardant was hypothesized: well-dispersed f-GNS constituted tortuous path and hindered the exchange process of degradation product with barrier function. Large quantities of degradation product gathered round f-GNS and reacted with flame retardant to produce the cross-linked and high-degree graphited residual char. The simple functionalization for electrochemically exfoliated graphene impels the application of graphene in the fields of flame retardant composites.