Electrochemical sensor for the analysis of 5-hydroxymethylcytosine in the presence of cytosine using pencil graphite electrode.

In recent years, important efforts have been made to elucidate the mechanisms of epigenetic regulation, and one of the most studied epigenetic modifications was DNA methylation/demethylation. In this study, the voltammetric behaviour of 5-hydroxymethylcytosine was studied in the pH range of 2.00-11.00 using pencil graphite electrodes by differential pulse and square wave voltammetry. The effect of buffer solutions, scan rate, square wave voltammetry parameters, and stripping conditions on the voltammetric responses of 5-hydroxymethylcytosine were performed. The electrochemical oxidation process of 5-hydroxymethylcytosine on the pencil graphite electrode was realized under adsorption control. In human urine, by square wave stripping voltammetry, 5-hydroxymethylcytosine was quantified in a concentration range of 1.00 × 10-5 M-2.00 × 10-4 M. The proposed method was tested in the presence of cytosine in human urine. The recovery value of 5-hydroxymethylcytosine was found to be 99.57 %.

Development of a molecularly imprinted polymer-based electrochemical sensor for the selective detection of nerve agent VX metabolite ethyl methylphosphonic acid in human plasma and urine samples.

This study focuses on the detection of ethyl methyl phosphonic acid (EMPA), a metabolite of the banned organophosphorus nerve agent VX. We developed an electrochemical sensor utilizing the molecularly imprinted polymer (MIP) based on 4-aminobenzoic acid (4-ABA) and tetraethyl orthosilicate for the selective detection of EMPA in human plasma and urine samples. The 4-ABA@EMPA/MIP/GCE sensor was constructed by a thermal polymerization process on a glassy carbon electrode and sensor characterization was performed by cyclic voltammetry and electrochemical impedance spectroscopy. The 4-ABA@EMPA/MIP/GCE sensor demonstrated impressive linear ranges 1.0 × 10-10 M-2.5 × 10-9 M for the standard solution, 1.0 × 10-10 M-2.5 × 10-9 M for the urine sample, and 1.0 × 10-10 M-1 × 10-9 M of EMPA for the plasma sample with outstanding detection limits of 2.75 × 10-11 M (standard solution), 2.11 × 10-11 M (urine), and 2.36 × 10-11 M (plasma). The sensor exhibited excellent recovery percentages ranging from 99.86 to 101.30% in urine samples and 100.62 to 101.08% in plasma samples. These findings underscore the effectiveness of the 4-ABA@EMPA/MIP/GCE as a straightforward, highly sensitive, and selective interface capable of detecting the target analyte EMPA in human plasma and urine samples.

The sensor applications for prostate and lung cancer biomarkers in terms of electrochemical analysis.

Prostate and lung cancers are the most common types of cancer and affect a large part of the population around the world, causing deaths. Therefore, the rapid identification of cancer can profoundly impact reducing cancer-related death rates and protecting human lives. Significant resources have been dedicated to investigating new methods for early disease detection. Cancer biomarkers encompass various biochemical entities, including nucleic acids, proteins, sugars, small metabolites, cytogenetic and cytokinetic parameters, and whole tumor cells in bodily fluids. These tools can be utilized for various purposes, such as risk assessment, diagnosis, prognosis, treatment efficacy, toxicity evaluation, and predicting a return. Due to these versatile and critical purposes, there are widespread studies on the development of new, sensitive, and selective approaches for the determination of cancer biomarkers. This review illustrates the significant lung and prostate cancer biomarkers and their determination utilizing electrochemical sensors, which have the advantage of improved sensitivity, low cost, and simple analysis. Additionally, approaches such as improving sensitivity with nanomaterials and ensuring selectivity with MIPs are used to increase the performance of the sensor. This review aims to overview the most recent electrochemical biosensor applications for determining vital biomarkers of prostate and lung cancers in terms of nanobiosensors and molecularly imprinted polymer (MIP)-based biosensors.

A novel Co/Zn-ferrite molecularly imprinted polymer-based electrochemical assay for sensing of gallic acid in plant extracts, wine, and herbal supplement.

In this study, a new molecularly imprinted polymer (MIP)-based sensor platform was developed for the electrochemical determination of gallic acid (GAL) in plant extracts, wine, and herbal supplements. Gallic acid is known for its natural antioxidant properties, which play an important role in preventing cell deterioration that can lead to various diseases. In addition, gallic acid has therapeutic potential due to its anticancer, antiinflammatory, antimicrobial, and neuroprotective properties. Accurate analysis of gallic acid in complex matrices, in mixed samples where different components coexist, is necessary to evaluate the efficacy and safety of this compound. Cobalt ferrite-zinc-dihydro caffeic acid (CFO_Zn_DHCA) nanoparticles, sphere-like in shape and 5 ± 1 nm in size, were incorporated into the MIP-based electrochemical sensor design to enhance the active surface area and porosity of the glassy carbon electrode (GCE) surface. The functional monomer chosen for this study was aminophenyl boronic acid (3-APBA). In the GAL/CFO_Zn_DHCA/3-APBA@MIP-GCE sensor, which was developed using photopolymerization (PP), 3-APBA as a functional monomer was designed, and obtained in the presence of basic monomer (HEMA), cross-linker (EGDMA), and initiator (2-hydroxy-2-methyl propiophenone) by keeping it under a UV lamp at 365 nm. It aims to detect GAL in real samples such as Punica granatum (pomegranate) peel, Camellia sinensis (green and black tea leaves), wine, and herbal supplements. Morphological and electrochemical characterizations of the designed GAL/CFO_Zn_DHCA/3-APBA@MIP-GCE sensor were carried out using scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The linear range for the determination of GAL using the indirect method (5.0 mM [Fe(CN)6]-3/-4) was found to be 1.0 × 10-13 M-1.0 × 10-12 M, and the limit of detection (LOD) and limit of quantification (LOQ) for standard solutions were calculated as 1.29 × 10-14 and 4.29 × 10-14 M, respectively. As a result of the study, the developed MIP-based electrochemical sensor was suitable for detecting GAL with high specificity, selectivity, and sensitivity. Recovery studies were performed to determine the practical applicability of the sensor, and the results were satisfactory. This innovative sensor platform stands out as a reliable and sensitive analytical tool for determining GAL.

Sensitive and selective determination of upadacitinib using a custom-designed electrochemical sensor based on ZnO nanoparticle-assisted molecularly imprinted polymer.

Upadacitinib (UPA) is a selective and reversible oral Janus kinase (JAK) 1 inhibitor and is of great importance in treating inflammatory bowel disease (Zheng et al., Int Immunopharmacol 126:111229, 2024; Foy et al., JAAD Case Rep 42:20-22, 2023). Although there are limitations to the effectiveness of UPA, it has received positive responses in clinical trials and is approved for the treatment of atopy dermatitis (AD) (Li et al., Int Immunopharmacol 125:111193, 2023). In this study, a nanoparticle-doped molecularly imprinted polymer (MIP)-based electrochemical sensor was developed for sensitive and selective detection of UPA. The developed sensor was designed as a thin film layer using the photopolymerization method on the surface of the prepared nanoparticle-doped polymerization solution glassy carbon electrode (GCE). Various nanoparticles, such as multi-walled carbon nanotube, titanium dioxide, oxide, and zinc oxide (ZnO) nanoparticles, were the most suitable for UPA. Surface characterization of the developed sensor was done by scanning electron microscopy (SEM), and electrochemical characterization was done by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The quantitative analysis of UPA was performed in 5.0 mM [Fe (CN)6]3-/4- solution using the differential pulse voltammetry (DPV) technique. Under optimum conditions, the calibration range was between 0.1 and 1 pM. The limit of detection (LOD) and limit of quantification (LOQ) were calculated as 0.005 pM and 0.017 pM, respectively. The sensor's accuracy was proven by performing a recovery study in serum. The sensor's selectivity was also evaluated using common interfering substances such as KNO3, CaCl2, Na2SO4, uric acid, ascorbic acid, dopamine, and paracetamol. According to the results obtained, the performance of the designed sensor was found to be quite sensitive and selective in determining UPA. The developed UPA-ZnO/3-APBA@MIP-GCE sensor showed high sensitivity and selectivity towards UPA. In addition, the selectivity, the most important feature of the MIP-based sensor, was confirmed by imprinting factor (IF) calculations using tofacitinib (TOF) and ruxolitinib (RUX). The sensor's unique selectivity is demonstrated by its successful performance even in the presence of UPA impurities.

Recent trends in core/shell nanoparticles: their enzyme-based electrochemical biosensor applications.

Improving novel and efficient biosensors for determining organic/inorganic compounds is a challenge in analytical chemistry for clinical diagnosis and research in biomedical sciences. Electrochemical enzyme-based biosensors are one of the commercially successful groups of biosensors that make them highly appealing because of their low cost, high selectivity, and sensitivity. Core/shell nanoparticles have emerged as versatile platforms for developing enzyme-based electrochemical biosensors due to their unique physicochemical properties and tunable surface characteristics. This study provides a comprehensive review of recent trends and advancements in the utilization of core/shell nanoparticles for the development of enzyme-based electrochemical biosensors. Moreover, a statistical evaluation of the studies carried out in this field between 2007 and 2023 is made according to the preferred electrochemical techniques. The recent applications of core/shell nanoparticles in enzyme-based electrochemical biosensors were summarized to quantify environmental pollutants, food contaminants, and clinical biomarkers. Additionally, the review highlights recent innovations and strategies to improve the performance of enzyme-based electrochemical biosensors using core/shell nanoparticles. These include the integration of nanomaterials with specific functions such as hydrophilic character, chemical and thermal stability, conductivity, biocompatibility, and catalytic activity, as well as the development of new hybrid nanostructures and multifunctional nanocomposites.

A comparative study of electropolymerization and photopolymerization for the determination of molnupiravir and their application in an electrochemical sensor via computationally designed molecularly imprinted polymers.

A comparative analysis of molecularly imprinted polymers based on different synthesis techniques was performed for the recognition of molnupiravir (MOL). The polymerizations were performed with 3-thienyl boronic acid (3-TBA) as a functional monomer by electropolymerization (EP) and with guanine methacrylate (GuaM) as a functional monomer by photopolymerization (PP). Morphological and electrochemical characterizations of the developed sensors were investigated to verify the constructed sensors. Moreover, quantum chemical calculations were used to evaluate changes on the electrode surface at the molecular and electronic levels. The dynamic linear range of both designed sensors under optimized experimental conditions was found to be 7.5 × 10-12-2.5 × 10-10 M and 7.5 × 10-13-2.5 × 10-11 M for EP and PP, respectively. The effect of various interfering agents on MOL peak current was assessed for the selectivity of the study. In the presence of 100 times more interfering agents, the RSD and recovery values were determined. The RSD values of GuaM/MOL@MIP/GCE and poly(Py-co-3-PBA)/MOL@MIP/GCE sensors were found to be 1.99% and 1.72%, respectively. Furthermore, the recovery values of the MIP-based sensors were 98.18-102.69% and 98.05-103.72%, respectively. In addition, the relative selectivity coefficient (k') of the proposed sensor was evaluated, and it exhibited good selectivity for MOL with respect to the NIP sensor. The prepared sensor was successfully applied to determine MOL in commercial serum samples and capsule form. In conclusion, the developed sensors provided excellent reproducibility, repeatability, high sensitivity, and selectivity against the MOL molecule.

Plant-based zinc nanoflowers assisted molecularly imprinted polymer for the design of an electrochemical sensor for selective determination of abrocitinib.

The first electrochemical sensor application in the literature is described for the sensitive and selective determination of the selective Janus kinase (JAK)-1 inhibitor abrocitinib (ABR). ABR is approved by the U.S. Food and Drug Administration (FDA) for the treatment of atopic dermatitis. The molecularly imprinted polymer (MIP)-based sensor was designed to incorporate zinc nanoflower (ZnNFs)-graphene oxide (GO) conjugate (ZnNFs@GO), synthesized from the root methanolic extract (RME) of the species Alkanna cappadocica Boiss. et Bal. to improve the porosity and effective surface area of the glassy carbon electrode (GCE). Furthermore, the MIP structure was prepared using ABR as a template molecule, 4-aminobenzoic acid (4-ABA) as a functional monomer, and other additional components. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the surface and structure of the synthesized nanomaterial and MIP-based surface. Among the electrochemical methods, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were preferred for detailed electrochemical characterization, and differential pulse voltammetry (DPV) was preferred for all other electrochemical measurements using 5.0 mM [Fe(CN)6]3-/4- solution as the redox probe. The MIP-based sensor, which was the result of a detailed optimization phase, gave a linear response in the 1.0 × 10-13 - 1.0 × 10-12 M range in standard solution and serum sample. The obtained limit of detection (LOD) and limit of quantification (LOQ) values and recovery studies demonstrated the sensitivity, accuracy, and applicability of the sensor. Selectivity, the most important feature of the MIP-based sensor, was verified by imprinting factor calculations using ibrutinib, ruxolitinib, tofacitinib, zonisamide, and acetazolamide.

A molecularly imprinted polymer-based electrochemical sensor for the determination of tofacitinib.

Tofacitinib citrate (TOF) is a Janus kinase-3 inhibitor used for rheumatoid arthritis treatment. In this study, a molecularly imprinted polymer (MIP)-based sensor was produced using acrylamide as the functional monomer via photopolymerization technique for the electrochemical determination of TOF. This study is the first one to explain the electrochemical determination of TOF with a highly selective MIP-based sensor. The surface characterization of the MIP-based sensor was performed with scanning electron microscopy and energy-dispersive X-ray spectroscopy methods, and it was expanded with electrochemical characterization by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) methods. TOF determination was performed using differential pulse voltammetry (DPV) and EIS methods in standard solution and spiked serum sample in the linear range between 1×10-11 M and 1×10-10 M. Very low limit of detection and limit of quantification values were found, confirming the sensitivity of the sensor. Recovery analysis with spiked serum and tablet samples verified the sensor's accuracy and applicability using DPV and EIS methods. The selectivity of the sensor was confirmed with imprinting factor and interference studies, and the sensor performance was controlled using non-imprinted polymer for comparison at every step.

Comparative MIP sensor technique: photopolymerization or thermal polymerization for the sensitive determination of anticancer drug Regorafenib in different matrixes.

Regorafenib (REG) is a diphenylurea derivative oral multikinase inhibitor. It plays an important role in the treatment of colorectal cancer, metastatic gastrointestinal stromal tumors, and hepatocellular carcinoma. Molecularly imprinted polymer (MIP) based glassy carbon electrodes (GCE) were fabricated using photopolymerization (PP) and thermal polymerization (TP) methods. The characterizations of the proposed sensors were investigated by electrochemical techniques, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). Several parameters were studied in detail for the optimum conditions of MIP-based sensors, such as dropping volume, photopolymerization and thermal polymerization durations, removal medium and time, and rebinding time. Both sensors' analytical validation and electroanalytical performance comparison were made in different REG concentrations ranging between 0.1 nM and 2.5 nM in standard solution and commercial human serum samples. The limit of detection (LOD) of PP-REG@MIP/GCE and TP-REG@MIP/GCE were 9.13 × 10-12 M and 1.44 × 10-11 M in standard solutions and 2.04 × 10-11 M and 2.02 × 10-11 M in serum samples, respectively. The applicability of the proposed sensors was tested using commercial human serum samples and pharmaceutical form of REG with high recovery values (PP-REG@MIP/GCE and TP REG@MIP/GCE sensors, 99.56-101.59%, respectively). The selectivity of the sensor for REG was investigated in the presence of similar molecules: Sorafenib, Sunitinib, Nilotinib, and Imatinib. The developed techniques and sensors checked the possible biological compounds and ions' effects and storage stability.

Recent biopharmaceutical applications of capillary electrophoresis methods on recombinant DNA technology-based products.

Biopharmaceuticals (recombinant technology-based products, vaccines, whole blood and blood components, gene therapy, cells, tissues, etc.,) are described as biological medical products produced from various living sources such as human, microbial, animal, and so on by manufacturing, extraction, or semi-synthesis. They are complex molecules having high molecular weights. For their safety and efficacy, their structural, clinical, physicochemical, and chemical features must be carefully controlled, and they must be well characterized by analytical techniques before the approval of the final product. Capillary electrophoresis (CE) having versatile modes can provide valuable safety and efficacy information, such as amino acid sequence, size variants (low and high molecular weight variants), charged variants (acidic and basic impurities), aggregates, N-linked glycosylation, and O-linked glycosylation. There are numerous applications of CE in the literature. In this review, the most significant and recent studies on the analysis of recombinant DNA technology-based products using different CE modes in the last ten years have been overviewed. It was seen that the researches mostly focus on the analysis of mAbs and IgG. In addition, in recent years, researchers have started to prefer CE combined mass spectrometry (MS) techniques to provide a more detailed characterization for protein and peptide fragments.

A porous molecularly imprinted electrochemical sensor for specific determination of bisphenol S from human serum and bottled water samples in femtomolar level.

In this study, a porous molecularly imprinted electrochemical sensor was successfully fabricated for the selective assay of bisphenol S (BPS) by introducing N-methacryloyl-L tyrosine functional monomer. The molecularly imprinted polymer (MIP)-based sensor (MA-Tyr@MIP/GCE) was prepared via photopolymerization on the glassy carbon electrode and subsequently characterized by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The analytical performance of the sensor was evaluated via CV and differential pulse voltammetry (DPV) measurements. Under the optimized conditions, the rebinding experiment demonstrated that the peak current of the porous MIP-based sensor obviously decreased with the increase of BPS concentration in the concentration range of 1-10 fM. Therefore, the detection limit was determined as 0.171 fM. It should be underlined that MA-Tyr@MIP/GCE exhibited high sensitivity and excellent selectivity because MA-TyrMA-Tyr@MIP/GCE sensor has a higher imprinting factor (IF) toward BPS in respect to competitive analogs, i.e., bisphenol A, bisphenol B, and bisphenol F. The practical application of the sensor also showed good reproducibility and stability for the detection of BPS in human serum and water samples. These results showed MA-Tyr@MIP/GCE successfully applied for the selective recognition of BPS in biological and water samples with high sensitivity and excellent selectivity.

Simple preparation of surface molecularly imprinted polymer based on silica particles for trace level assay of bisphenol F.

A new electrochemical sensor based on molecularly imprinted tetraethyl orthosilicate (TEOS)-based porous interface was developed for selective recognition of bisphenol F (BPF) in this study. The sensor was prepared by depositing the solution containing TEOS and L-tryptophan (L-Trp) in the presence of cetyltrimethylammonium bromide (CTAB) as a pore-maker via hydrolysis/condensation reaction on the glassy carbon electrode (GCE). While the surface morphology and structure characterization were carried out using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), electrochemical characterization was performed through electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The resulted MIP(TEOS:L-Trp)@GCE achieved a wide linear range of 1 × 10-15-1 × 10-14 M for BPF detection with an excellent detection limit of 0.291 fM. Furthermore, the recovery of BPF from spiked bottled water and serum samples varied between 98.83 and 101.03%. These results demonstrate that MIP(TEOS:L-Trp)@GCE was found to be a simple, sensitive, and selective smart interface to detect trace pollution even from complicated samples.

A semi-covalent molecularly imprinted electrochemical sensor for rapid and selective detection of tiotropium bromide.

Tiotropium bromide (TIO) is a long-acting bronchodilator used in the treatment of chronic obstructive pulmonary disease (COPD) and asthma. Specifically, it is used to prevent patients from worsening breathing difficulties. In this study, a new TIO-imprinted electrochemical sensor was designed to detect TIO in serum and pharmaceutical samples. Methacryloyl-L-histidine-cobalt(II) [MAH-Co(II)] has been used as a metal-chelating monomer for synthesizing selective molecularly imprinted polymer (MIP). MIP film has been developed on glassy carbon electrodes using MAH-Co(II) as the functional monomer, 2-hydroxyethyl methacrylate (HEMA) as the basic monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker in the photopolymerization method. The surface characterization of the developed MAH-Co(II)@MIP/GCE electrochemical sensor was done using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Also, the electrochemical behavior of the sensor was provided by differential pulse voltammetry (DPV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques. Under optimized experimental conditions, the linearity range was in the range of 10-100 fM, and the limit of detection (LOD) and limit of quantitation (LOQ) values were calculated as 2.73 fM and 9.75 fM, respectively. The MAH-Co(II)@MIP/GCE sensor was used to precisely determine TIO in capsule and commercial serum samples. The results demonstrated that the MIP could specifically recognize TIO compared to structurally related drugs and could be reliably applied to the direct determination of drugs from real samples.

Enantioselective recognition of esomeprazole with a molecularly imprinted sol-gel-based electrochemical sensor.

A simple, selective, and accurate electrochemical chiral sensor based on molecularly imprinted polymer (MIP) has been developed for sensitive and selective detection of esomeprazole (ESOM). For this purpose, the porous MIP sensor was prepared using tetraethyl orthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) in the presence of ß-cyclodextrin (ß-CD) as a chiral recognizing element on a glassy carbon electrode (GCE). The changes in the MIP-layer related to removal and rebinding of the target ESOM were performed via differential pulse voltammetry (DPV) and cyclic voltammetry (CV) by using [Fe(CN)6]3-/4- as the redox probe. The structures of the developed sensor surface were characterized by using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical impedance spectroscopy (EIS) was also utilized for a complementary electrochemical characterization. The calibration curve was obtained in the range 1.0 × 10-14-2.0 × 10-13 M with a limit of detection (LOD) of 1.9 × 10-15 M. The developed method has improved the accessibility of binding sites by producing the porous material via hydrolysis/condensation reaction of TEOS in presence of CTAB. The selectivity tests of the developed SiO2-ß-CD@MIP/GCE sensor indicated a high specificity towards ESOM compared with structurally related competitor molecules such as R-omeprazole (R-OM), R-lansoprazole, and S-lansoprazole. The developed sensor was successfully used to determine ESOM in tablets and commercial human serum samples with satisfactory recoveries (100.25 to 100.60%) and precision (RSD 0.46 to 0.66%).

Determination of phenytoin in exhaled breath condensate using electromembrane extraction followed by capillary electrophoresis.

Application of hollow fiber-based electromembrane extraction was studied for extraction and quantification of phenytoin from exhaled breath condensate (EBC). Phenytoin is extracted from EBC through a supported liquid membrane consisting of 1-octanol impregnated in the walls of a hollow fiber, and into an alkaline aqueous acceptor solution inside the lumen of the fiber. Under the obtained conditions of electromembrane extraction, that is, the extraction time of 15 min, stirring speed of 750 rpm, donor phase pH at 11.0, acceptor pH at 13.0, and an applied voltage of 15 V across the supported liquid membrane, an enrichment factor of 102-fold correspond to extraction percent of 25.5% was achieved. Good linearity was obtained over the concentration range of 0.001-0.10 µg/mL (r2 = 0.9992). Limits of detection and quantitation were 0.001 and 0.003 µg/mL, respectively. The proposed method was successfully applied to determine phenytoin from EBC samples of patients receiving the drug. No interfering peaks were detected that indicating excellent selectivity of the method. The intra- and interday precisions (RSDs) were less than 14%.

Effect of monomer structure of anionic surfactant on voltammetric signals of an anticancer drug: rapid, simple, and sensitive electroanalysis of nilotinib in biological samples.

A rapid, simple, and highly sensitive electroanalytical method was developed for the first time for the detection of ultra-trace amounts of nilotinib in sodium lauryl sulphate media. The electrochemical behavior of nilotinib was investigated on a glassy carbon electrode in the absence and presence of sodium lauryl sulphate media by cyclic voltammetry and adsorptive stripping voltammetric methods. The cyclic voltammograms proved that the electrochemical behavior of nilotinib showed irreversible and diffusion-adsorption-controlled oxidation processes in 0.1 M H2SO4. The effect of surfactant concentration on the first and second peaks of nilotinib was examined. Depending on whether the surfactants had a monomer or monolayer hemimicelle structure, they were attracted to amine moieties at related points in the nilotinib structure through the electrostatic interaction. The sensitivity of the method was markedly enhanced in the presence of surfactants using adsorptive stripping square-wave voltammetry. Under optimum conditions, nilotinib was determined in a concentration range of 2.0 × 10-8 to 2.0 × 10-6 mol L-1, with a limit of detection of 6.33 × 10-9 mol L-1 in 0.1 M H2SO4 containing 2.0 × 10-7 mol L-1 sodium lauryl sulphate. The proposed method can be applied for the sensitive determination of nilotinib in biological samples. Graphical abstract.

Non-enzymatic monitoring of hydrogen peroxide using novel nanosensor based on CoFe2O4@CdSeQD magnetic nanocomposite and rifampicin mediator.

In this work, a novel strategy was introduced to develop a non-enzymatic hydrogen peroxide (H2O2) sensor based on rifampicin (RIF) electrodeposited on a polyvinylpyrrolidone (PVP)-capped CdSe quantum dot (CdSeQD), CoFe2O4 magnetic nanoparticle-modified glassy carbon electrode (CoFe2O4@CdSeQDs/RIF/GCE). CoFe2O4@CdSeQD magnetic nanocomposite (CoFe2O4@CdSeQD MNCs) was synthesized by a chemical co-precipitation method and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). To prepare the non-enzymatic H2O2 sensor, firstly, the glassy carbon electrode surface was modified by dropping 10 µL of 5 mg mL-1 CoFe2O4@CdSeQD MNCs. Then, rifampicin was electrodeposited on the activated CoFe2O4@CdSeQDs/GCE by applying a potential of - 0.7 V for 400 s in pH 2.0 phosphate buffer containing 190 µM of rifampicin. Cyclic voltammetry and electrochemical impedance spectroscopy was used to investigate the electrochemical behavior of this sensor and was used for the reduction of H2O2. Construction of the calibration plot for H2O2 was performed using an amperometric method (- 0.2 V vs. Ag/AgCl) at the modified electrode. Two linearity ranges were obtained from 7 to 145 µM and 145 µM to 1.43 mM with sensitivities of 143.01 µA mM-1 and 28.67 µA mM-1 for the first and second linearity ranges, respectively. The detection limit was obtained as 0.38 µM (S/N = 3). Finally, the reliability of the nanosensor was confirmed with real sample analysis in different beverages such as juice and milk with satisfactory recovery results.

A novel stability-indicating analytical method development for simultaneous determination of carboplatin and decitabine from nanoparticles.

Drug resistance is one of the main problems of cancer treatment. For this reason, combination therapy is commonly used for years. The combination of a chemotherapeutic, carboplatin, and the epigenetic drug decitabine is a new approach to modulate drug resistance. Nanoparticulate systems can overcome the drawbacks associated with the drug combinations. An analytical method that can detect and quantify carboplatin and decitabine which is encapsulated into the nanoparticles is necessary for nanoparticle development. In the literature, there is no analytical method in which carboplatin and decitabine are determined simultaneously. The primary purpose of this study is to develop and validate a novel, and stability-indicating high-performance liquid chromatography method for simultaneous determination of carboplatin and decitabine in pharmaceutical preparations in addition to developing the first nanoformulation for this drug combination. Therefore, various experimental parameters were optimized. The chromatographic separation was achieved using an XSelect® CSH C18 (250 × 4.6 mm I.D., 5 µm) column and a mobile phase consisting of methanol:water (containing 0.1% phosphoric acid) (3:97, v/v). The mobile phase pH was adjusted to 7.0 with 5 M NaOH. The developed method was successfully applied for the simultaneous determination and quantification of carboplatin and decitabine co-encapsulated in nanoparticles and released into in vitro dissolution medium.

The Effect of Enantiomer Elution Order on the Determination of Minor Enantiomeric Impurity in Ketoprofen and Enantiomeric Purity Evaluation of Commercially Available Dexketoprofen Formulations.

In a recent study, opposite enantiomer elution order was observed for ketoprofen enantiomers on two amylose-phenylcarbamate-based chiral columns with the same chemical composition of the chiral selector but in one case with coated while in the other with an immobilized chiral selector. In the present study, the influence of this uncommon effect on method validation parameters for the determination of minor enantiomeric impurity in dexketoprofen was studied. The validated methods with two alternative elution orders for enantiomers were applied for the evaluation of enantiomeric impurity in six marketed dexketoprofen formulations from various vendors. In most of these formulations except one the content of enantiomeric impurity exceeded 0.1% (w/w).