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.

Pretreatment and analysis techniques development of TKIs in biological samples for pharmacokinetic studies and therapeutic drug monitoring

Tyrosine kinase inhibitors (TKIs) have emerged as the first-line small molecule drugs in many cancer therapies, exerting their effects by impeding aberrant cell growth and proliferation through the modulation of tyrosine kinase-mediated signaling pathways. However, there exists a substantial inter-individual variability in the concentrations of certain TKIs and their metabolites, which may render patients with compromised immune function susceptible to diverse infections despite receiving theoretically efficacious anticancer treatments, alongside other potential side effects or adverse reactions. Therefore, an urgent need exists for an up-to-date review concerning the biological matrices relevant to bioanalysis and the sampling methods, clinical pharmacokinetics, and therapeutic drug monitoring of different TKIs. This paper provides a comprehensive overview of the advancements in pretreatment methods, such as protein precipitation (PPT), liquid-liquid extraction (LLE), solid-phase extraction (SPE), micro-SPE (μ-SPE), magnetic SPE (MSPE), and vortex-assisted dispersive SPE (VA-DSPE) achieved since 2017. It also highlights the latest analysis techniques such as newly developed high performance liquid chromatography (HPLC) and high-resolution mass spectrometry (HRMS) methods, capillary electrophoresis (CE), gas chromatography (GC), supercritical fluid chromatography (SFC) procedures, surface plasmon resonance (SPR) assays as well as novel nanoprobes-based biosensing techniques. In addition, a comparison is made between the advantages and disadvantages of different approaches while presenting critical challenges and prospects in pharmacokinetic studies and therapeutic drug monitoring.

Application of lipid and polymeric-based nanoparticles for treatment of inner ear infections via XGBoost

Taking hearing loss as a prevalent sensory disorder, the restricted permeability of blood flow and the blood-labyrinth barrier in the inner ear pose significant challenges to transporting drugs to the inner ear tissues. The current options for hear loss consist of cochlear surgery, medication, and hearing devices. There are some restrictions to the conventional drug delivery methods to treat inner ear illnesses, however, different smart nanoparticles, including inorganic-based nanoparticles, have been presented to regulate drug administration, enhance the targeting of particular cells, and decrease systemic adverse effects. Zinc oxide nanoparticles possess distinct characteristics that facilitate accurate drug delivery, improved targeting of specific cells, and minimized systemic adverse effects. Zinc oxide nanoparticles was studied for targeted delivery and controlled release of therapeutic drugs within specific cells. XGBoost model is used on the Wideband Absorbance Immittance (WAI) measuring test after cochlear surgery. There were 90 middle ear effusion samples (ages = 1-10 years, mean = 34.9 months) had chronic middle ear effusion for four months and verified effusion for seven weeks. In this research, 400 sets underwent wideband absorbance imaging (WAI) to assess inner ear performance after surgery. Among them, 60 patients had effusion Otitis Media with Effusion (OME), while 30 ones had normal ears (control). OME ears showed significantly lower absorbance at 250, 500, and 1000 Hz than controls (p < 0.001). Absorbance thresholds >0.252 (1000 Hz) and >0.330 (2000 Hz) predicted a favorable prognosis (p < 0.05, odds ratio: 6). It means that cochlear surgery and WAI showed high function in diagnosis and treatment of inner ear infections. Regarding the R2 0.899 and RMSE 1.223, XGBoost shows excellent specificity and sensitivity for categorizing ears as having effusions absent or present or partial or complete flows present, with areas under the curve (1-0.944).

A disposable electrochemical sensor based on single-walled carbon nanotubes for the determination of anticancer drug dasatinib

Dasatinib is an anticancer drug that treats acute lymphoblastic leukemia, chronic myelogenous leukemia, and prostate cancer with several side effects. In this research, we suggest nanoparticle-modified screen-printed electrodes (SPCEs) as disposable electrochemical sensors for fast quantification of dasatinib in pharmaceutical formulations. Carbon nanotubes, single-walled carbon nanotubes (SWCNT), graphene, and graphene oxide-modified SPCEs were characterized by scanning electron microscopy. The study also recommends SWCNT-modified SPCEs as the best-performing electrode for determining dasatinib, demonstrating an excellent boosting effect on the oxidation response of dasatinib. This was accomplished using the square-wave voltammetry method. After optimization of the pH condition, pH 5.0 Britton–Robinson buffer, SWCNT-modified SPCEs demonstrated 94% recovery with optimum electro-oxidation activity. The oxidation currents exhibited linear relation with dasatinib concentration in the 0.1–100 µM. Based on the results, a limit of detection of 0.06 µM was obtained in the standard solution. The SWCNT-modified SPCEs have been applied to analyze dasatinib in pharmaceutical tablet samples. The demonstrated performance beats all comparable standard analytical tools and presumably may be used for general drug quantitation in pharmaceutical tablets.

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Application of oxidized multi-walled carbon nanotubes and zeolite nanoparticles for simultaneous preconcentration of codeine and tramadol in saliva prior to HPLC determination

In this work, a dispersive micro-solid phase extraction technique along with high-performance liquid chromatography-UV detection was developed for simultaneous preconcentraion and determination of trace levels of codeine and tramadol in human saliva. This method is based on the adsorption of codeine and tramadol on a mixture of oxidized multi-walled carbon nanotubes and zeolite Y nanoparticles with 1:1 ratio as an efficient nanosorbent. Various analytical parameters influencing the adsorption step including the amount of adsorbent, the pH of the sample solution, the temperature, the stirring rate, the contact time of the sample solution, and the adsorption capacity were investigated. Based on the results, 10 mg adsorbent, sample solutions with pH = 7.6, temperature of 25 °C, stirring rate 750 rpm and contact time 15 min, in the adsorption step shows the best results for both drugs. Then the effective parameters on the analyte desorption stage such as the type of desorption solution, pH of the desorption solution, desorption time and desorption volume were investigated. Studies have shown that water/methanol (50:50 v/v) as desorption solution, pH = 2.0, desorption time of 5 min and desorption volume of 2 ml gives the best results.Chromatographic separation was performed on a RP-Shim-pack CLC-ODS-C18 column (250 mm × 4.6 mm, 5 µm) with isocratic mode. The mobile phase contained of acetonitrile:phosphate buffer (18:82, v/v) at pH = 4.5 and the flow rate was 1 ml.min^-1. The wavelength of UV detector was adjusted at 210 nm and 198 nm for codeine and tramadol, respectively.Under optimum conditions, the extraction efficiencies of 98.5% and 99.2% were achieved for codeine and tramadol respectively. Enrichment factor of 13, detection limit of 0.3 μg L^-1, relative standard deviation of 4.07 for codeine; and an enrichment factor of 15, a detection limit of 0.15 μg L^-1, and standard deviation of 2.06 for tramadol were calculated. The linear range of the procedure for each drug was 1.0 to 1000 μg L^-1. This method was successfully applied for the analysis of codeine and tramadol in saliva samples.

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.

A zinc oxide nanorods/molybdenum disulfide nanosheets hybrid as a sensitive and reusable electrochemical sensor for determination of anti-retroviral agent indinavir

This work aims to develop an electrochemical sensor for the reusable and selective detection of trace levels of indinavir (IDV) as an anti-retroviral drug by using zinc oxide nano-rods/molybdenum disulfide nanosheets on a screen-printed electrode (ZnO NRs/MoS₂ NSs/SPE). Quantitative IDV detection was achieved using differential pulse voltammetry (DPV). The assay specificity was illustrated using interfering species and exhibited high specificity toward the IDV. The developed displayed a wide dynamic range, from 0.01 to 0.66 and 0.66-7.88 μM in Britton-Robinson (B-R) buffer, with a 0.007 μM limit of detection. The fabricated ZnO NRs/MoS₂ NSs/SPE electrode exhibited high sensitivity, stability, good reproducibility, and repeatability towards the sensing of IDV. It turned out that the hybrid electrochemical sensor's sensing performance was remarkably improved due to the synergistic effect between MoS₂ NSs and ZnO NRs, where the former affords a large active surface area and quick electron transfer. The reported sensor provides a new alternative for electrochemical detection of IDV and could expand the applications of metal nanoparticles in emerging technologies for monitoring drugs in real samples.

An electrochemical molecularly imprinted sensor based on CuBi2O4/rGO@MoS2 nanocomposite and its utilization for highly selective and sensitive for linagliptin assay

The molecularly imprinted polymers (MIP) is an outstanding electrochemical tool that demonstrates good chemical sensitivity and stability. These main advantages, coupled with the material's vast microfabrication flexibility, make molecularly imprinted sensors an attractive sensing device. Herein, it was aimed to develop a state-of-art molecularly imprinted sensor based on CuBi₂O₄/rGO@MoS₂ nanocomposite to be utilized for the detection of linagliptin (LNG), a novel hypoglycemic drug. The electrochemical characterizations of linagliptin on the surface of the modified electrode was examined via cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Several characterization methods including transmission electron microscope (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Energy-dispersive X-ray spectroscopy(EDX), were utilized for electrode characterization. The LNG imprinted voltammetric sensor was developed in 80.0 mM phenol containing 20.0 mM LNG. CuBi₂O₄/rGO@MoS₂ nanocomposite on LNG imprinted screen-printed carbon electrode (SPCE) (MIP/CuBi₂O₄/rGO@MoS₂ nanocomposite/SCPE) exhibited a linear relationship between peak current and LNG concentration in the range 0.07-0.5 nM with a detection limit of 0.057 nM. In the existence of interfering substances, an LNG imprinted electrode was utilized to analyze urine, human plasma, and tablet samples with adequate selectivity. The developed sensor was also illustrated for stability, repeatability, reproducibility, and reusability.

A green and sensitive guanine-based DNA biosensor for idarubicin anticancer monitoring in biological samples: A simple and fast strategy for control of health quality in chemotherapy procedure confirmed by docking investigation

Drug efficiency can be considerably boosted while adverse effects can be reduced by precisely monitoring the concentration of anti-cancer drugs. Thus, one of the most important parameters for human health is the monitoring and detection of anticancer drugs during chemotherapy treatment. Herein, a glassy carbon electrode (GCE) was modified by Pt- and Pd-incorporated ZnO nanoparticles-decorated single-wall carbon nanotubes (Pt-Pd-ZnO/SWCNTs) nanocomposites, and ds-DNA (Calf Thymus) that was a biological recognition element, and it was aimed to be utilized as an ultrasensitive and effective electroanalytical biosensor for idarubicin (IDR) monitoring. Various physicochemical characterization techniques including transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy (EDS) were used to investigate the morphology and structure of the Pt-Pd-ZnO/SWCNTs nanocomposite, which was produced via straightforward chemical precipitation combined with the one-pot method. The layer-by-layer modification technique was implemented to fabricate the ds-DNA/Pt-Pd-ZnO/SWCNTs/GCE to be further utilized as a voltammetric sensor for sensitive monitoring of idarubicin in biological fluids and pharmaceutical substances. The electroanalytical method implemented to detect idarubicin was based to detect the ds-DNA's guanine base signal on the surface of the modified electrode in the absence and presence of the anticancer drug. The results explicated that the developed biosensor performed well in determining idarubicin in concentrations ranging from 1.0 nM to 65 μM, with a detection limit of 0.8 nM. The idarubicin detection ability of the modified electrode in real samples was evaluated, and the recovery data was acquired in the range of 98.0% and 104.75%. In the final step, the preferential intercalative binding mode of idarubicin drug with ds-DNA was approved by molecular docking study. This study paves the way for engineering highly sensitive DNA biosensors to be employed in the monitoring of anticancer drugs by combining the benefits of nanocomposites and valuable information of a molecular docking study.

Ultrasound-assisted green synthesis of gold nanoparticles using citrus peel extract and their enhanced anti-inflammatory activity

Ultrasound and plant extract are two green approaches that have been used to synthesize gold nanoparticles (AuNPs); however, how the combination of ultrasound and citrus peel extract (CPE) affects the structure characteristics and the bioactivity of AuNPs remains unknown. Here we investigated the effects of ultrasound conditions on the particle size, stability, yield, phenolic encapsulation efficacy, and the anti-inflammatory activity of AuNPs. The results showed that temperature was positively correlated to the particle size and the anti-inflammatory activity of synthesized AuNPs. Increasing the power intensity significantly decreased the particle size, while increased the change of total phenolic content (ΔTPC) in the reaction mixture. The increase of ΔTPC caused the enhanced anti-inflammatory activity of AuNPs. The AuNPs synthesized with or without ultrasound treatment were characterized using UV-Vis, DLS, SEM, TEM, EDS, XRD, and FT-IR. The result verified the formation of negatively charged, spherical, stable, and monodispersed AuNPs. AuNPs synthesized with ultrasound (AuNPs-U) has smaller particle size (13.65 nm vs 16.80 nm), greater yield and anti-inflammatory activity (IC₅₀, 82.91 vs 157.71 μg/mL) than its non-ultrasound counterpart (AuNPs-NU). HPLC analysis showed that hesperidin was the key reductant for the synthesis of AuNPs. AuNPs-U also inhibited the mRNA and protein expression of iNOS and COX-2 in the LPS-induced Raw 264.7 cells. Our research elucidates the relationship between the reaction conditions and the structure characteristics and the anti-inflammatory activity of AuNPs synthesized using CPE with the help of ultrasound, thereafter, provides a feasible and economic way to synthesize AuNPs that can be used to ameliorate inflammation.

A New Electrochemical Platform for Dasatinib Anticancer Drug Sensing Using Fe3O4-SWCNTs/Ionic Liquid Paste Sensor

A new electrochemical platform was suggested for the sensing of the dasatinib (DA) anticancer drug based on paste electrode modification (PE) amplified with Fe₃O₄-SWCNTs nanocomposite and 1-hexyl-3-methylimidazolium tetrafluoroborate (mim-BF₄⁻). The new platform showed a linear dynamic range from 0.001–220 µM with a detection limit of 0.7 nM to determine DA at optimal condition. Electrochemical investigation showed that the redox reaction of DA is relative to changing the pH of solution. Moreover, Fe₃O₄-SWCNTs/mim-BF₄⁻/PE has improved the oxidation current of DA about 5.58 times which reduced its oxidation potential by about 120 mV at optimal condition. In the final step, Fe₃O₄-SWCNTs/mim-BF₄⁻/PE was used as an analytical platform to determine the DA in tablets and a dextrose saline spike sample, and the results showed recovery data 99.58–103.6% which confirm the powerful ability of the sensor as an analytical tool to determine the DA in real samples.

Carbon-based ruthenium nanomaterial-based electroanalytical sensors for the detection of anticancer drug Idarubicin

In this work, a novel nanosensing platform was suggested based on ruthenium for the sensitive determination of Idarubicin anticancer drugs. Ruthenium/Vulcan carbon-based nanoparticles were synthesized ultrasonication method and then characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The mean particle size of the nanoparticles calculated by the TEM analysis was found to be 1.98 nm ± 0.29 nm, and the Ru nanoparticles were mostly dispersed on the support material. Glassy carbon electrode (GCE) surface was modified with Ruthenium/Vulcan carbon-based nanomaterials (Ru@VC), and characterization of the nanosensor was performed using electrochemical impedance spectroscopy and cyclic voltammetry. The limit of detection (LOD) and limit of quantification (LOQ) values were found as 9.25 × 10^–9 M and 2.8 × 10^–8 M in buffer samples. To demonstrate the applicability and validity of developed nanosensor, it was used for the determination of Idarubicin in Idamen^® IV (10 mg/10 mL vial) and human serum sample. The results of recovery studies showed that the Ru@VC/GCE nanosensor was free from excipient interferences in the dosage forms of injection, and it can be successfully applied to biological samples.

Electrochemistry as a screening method in determination of carotenoids in crustacean samples used in everyday diet

Electrochemistry of carotenoids has attracted a lot of interest because it provides an understanding of their oxidative properties. We report the application of electrochemistry in the analysis of carotenoids. Voltammetry of microdroplets immobilized on paraffin impregnated graphite electrode in 0.1 mol dm^-3 HClO₄ and KNO₃ aqueous electrolytes using square-wave voltammetry was applied. Previous studies have shown that carotenoids undergo complex oxidation process when characterized in aqueous media. In this research, the electrooxidation of carotenoid astaxanthin was confirmed. The obtained response allowed the development of an electroanalytical method with a limit of detection of 15.77 µmol dm^-3, the limit of quantification of 47.80 µmol dm^-3 and acceptable relative standard deviations for current (3.69%) and potential (0.41%). Extraction using DMSO and acetone has shown to be appropriate for voltammetric analysis. Astaxanthin content was determined electrochemically in shrimp and soft-shell crab samples (20.63 and 6.59 μg g^-1, respectively), yielding recoveries above 90%.

Electrochemical DNA Biosensors Based on Labeling with Nanoparticles

This work reviews the field of DNA biosensors based on electrochemical determination of nanoparticle labels. These labeling platforms contain the attachment of metal nanoparticles (NPs) or quantum dots (QDs) on the target DNA or on a biorecognition reporting probe. Following the development of DNA bioassay, the nanotags are oxidized to ions, which are determined by voltammetric methods, such as pulse voltammetry (PV) and stripping voltammetry (SV). The synergistic effects of NPs amplification (as each nanoprobe releases a large number of detectable ions) and the inherent sensitivity of voltammetric techniques (e.g., thanks to the preconcentration step of SV) leads to the construction of ultrasensitive, low cost, miniaturized, and integrated biodevices. This review focuses on accomplishments in DNA sensing using voltammetric determination of nanotags (such as gold and silver NPs, and Cd- and Pb-based QDs), includes published works on integrated three electrode biodevices and paper-based biosystems, and discusses strategies for multiplex DNA assays and signal enhancement procedures. Besides, this review mentions the electroactive NP synthesis procedures and their conjugation protocols with biomolecules that enable their function as labels in DNA electrochemical biosensors.

Defect and Additional Active Sites on the Basal Plane of Manganese-Doped Molybdenum Diselenide for Effective Enzyme Immobilization: In Vitro and in Vivo Real-Time Analyses of Hydrogen Peroxide Sensing

The defect engineering makes the new concepts and designs to further enhance the electrocatalytic activity of layered structures. In this work, we demonstrated the synthesis of Mn-doped MoSe₂ and reported the resultant defective sites. Subsequently, the MnMoSe₂ was developed as a new type of electrocatalyst for electrochemical biosensors. The formation of defect/distortion and effective immobilization of myoglobin (Mb) were evidently confirmed by using the transmission electron microscopy and UV-vis spectroscopy analyses, respectively. The result of electrochemical impedance spectroscopy analysis reveals that the Mn doping not only helps  to enzyme immobilization but also enhances the electronic conductivity of layered material.  Owing to the multiple signal amplification strategies, the proposed Mb-immobilized MnMoSe₂ (Mb@MnMoSe₂) exhibited an ultralow detection limit (0.004 μM) and a higher sensitivity (222.78 μA μM^-1 cm^-2) of H₂O₂. In real-sample analysis, the Mb@MnMoSe₂ showed a feasible recovery range of H₂O₂ detection in human serum (95.6-102.1%), urine (101.2-102.3%), and rain water (100.7-102.1%) samples. On the other hand, an in vivo study using HaCaT (7.1 × 10⁵/mL) and RAW 264.7 (1 × 10⁶/mL) living cells showed the feasible current responses of 0.096 and 0.085 μA, respectively. Finally, the Mn doping gives a new opportunity to fabricate a promising electrocatalyst for H₂O₂ biosensing.

A novel electrochemical epinine sensor using amplified CuO nanoparticles and an-hexyl-3-methylimidazolium hexafluorophosphate electrode

This study suggests a carbon paste electrode modified with CuO nanoparticles andn-hexyl-3-methylimidazolium hexafluorophosphate (CPE/CuO-NPs/HMIPF₆) as a powerful tool for the analysis of epinine for the first time.

Facile Solvothermal Preparation of Mn2CuO4 Microspheres: Excellent Electrocatalyst for Real-Time Detection of H2O2 Released from Live Cells

Hydrogen peroxide (H₂O₂) is an eminent biomarker in pathogenesis; a selective, highly sensitive real-time detection of H₂O₂ released from live cells has drawn a significant research interest in bioanalytical chemistry. Binary transition-metal oxides (BTMOs) displayed a recognizable benefit in enhancing the sensitivity of H₂O₂ detection; although the reported BTMO-based H₂O₂ sensor's detection limit is still insufficient, it is not appropriate for in situ profiling of trace amounts of cellular H₂O₂. In this paper, we describe an efficient, reliable electrochemical biosensor based on Mn₂CuO₄ (MCO) microspheres to assay cellular H₂O₂. The Mn₂CuO₄ microspheres were prepared through a superficial solvothermal method. It is obvious from impedance studies, introduction of manganese into copper oxide lattice significantly improved the ionic conductivity, which is beneficial for the electrochemical sensing process. Thanks to the distinct microsphere structure and excellent synergy, MCO-modified electrode exhibited excellent nonenzymatic electrochemical behavior toward H₂O₂ sensing. The MCO-modified electrode delivered a broad working range (36 nM to 9.3 mM) and an appreciable detection limit (13 nM), with high selectivity toward H₂O₂. To prove its practicality, the developed sensor was applied in the detection of cellular H₂O₂ released by RAW 264.7 cells in presence of CHAPS. These results label the possible appliance of the sensor in clinical analysis and pathophysiology. Thus, BTMOs are evolving as a promising candidate in designing catalytic matrices for biosensor applications.