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In this work, a novel strategy was introduced to develop a non-enzymatic hydrogen peroxide (H

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%.

In this study, a novel and sensitive nanocomposite of carboxylate-functionalized multiwalled carbon nanotube (COOH-fMWCNT) and silver nanoparticles (AgNPs) was fabricated and used to modify a glassy carbon electrode (GCE) by a simple drop casting method. Modified electrode was then applied for selective determination of emedastine difumarate (EDD). The COOH-fMWCNT/AgNPs nanocomposite was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and cyclic voltammetry (CV). EDD showed two oxidation peaks at 0.634 and 1.2 V on the GCE surface. CV results of COOH-fMWCNT/AgNPs/GCE displayed superior electrocatalytic performance in terms of anodic peak current of EDD when compared to AgNPs/GCE, MWCNT/GCE, and COOH-fMWCNT/GCE. The experimental conditions such as effect of pH, supporting electrolyte, effect of accumulation time and potential, scan rate were optimized for getting intense current signals of the target analyte. Under optimized conditions, COOH-fMWCNT/AgNPs/GCE showed a linear current response for oxidation of EDD in the range of 1.0 × 10−7–1.0 × 10-4 M, with a limit of detection (LOD) and quantification (LOQ) of 5.25 nM, 15.9 nM, respectively, in 0.1 M phosphate buffer solution at pH 2.0 using differential pulse adsorptive stripping voltammetry technique. The proposed method was successfully applied for determination of EDD in pharmaceutical dosage form. Satisfactory recovery percentages were achieved from eye drop sample with acceptable RSD values (less than 2 %). Furthermore, the reproducibility, stability and repeatability of the modified electrode were studied.

Nowadays, electrochemical techniques can be considered as a suitable alternative technique besides UV/Vis spectroscopy, liquid chromatography, capillary electrophoresis, mass spectroscopy, NMR for evaluation and determination of different electroactive compounds. Solid electrodes such as carbon and metal-based substrates are common for electrochemical applications. Especially, during two past decades, different types of modified electrodes with these solid electrodes have been developed for fast, sensitive, and selective analysis of various important analyses (biomolecules, enzymes, and drugs) in a wide range of real samples. These applications are highly efficient, cost effective and facile fabrication procedures of the electrode modification can be employed. In the present review, at first, some recently developed high performance bare and modified electrodes are evaluated based on their outstanding properties. In the next step, developed new procedures or fabricated modified electrodes with good sensitivity based on simple and cheap protocols are introduced and discussed.

An immunosensor is a kind of affinity biosensor based on interactions between an antigen and specific antigen immobilized on a transducer surface. Immunosensors possess high selectivity and sensitivity due to the specific binding between antibody and corresponding antigen, making them a suitable platform for several applications especially in the medical and bioanalysis fields. Electrochemical immunosensors rely on the measurements of an electrical signal recorded by an electrochemical transducer and can be classed as amperometric, potentiometric, conductometric, or impedimetric depending on the signal type. Among the immunosensors, electrochemical immunosensors have been more perfected due to their simplicity and, especially their ability to be portable, and for in situ or automated detection. This review addresses the potential of immunosensors destined for application in clinical analysis, especially cancer biomarker diagnosis. The emphasis is on the approaches used to fabricate electrochemical immunosensors. A general overview of recent applications of the developed electrochemical immunosensors in the clinical approach is described.

A novel sensor based on a modification of glassy carbon electrode (GCE) with NH2-functionalized multi walled carbon nano-tubes (NH(2)fMWCNTs) is reported and its applicability to the electrochemical sensing of Propafenone (PPF) demonstrated. The electrochemical catalytic activity was also utilized as a sensitive detection method for the investigation of the detailed redox mechanism of PFF using cyclic and and differential pulse voltammetry. The surface morphology of the sensor was investigated by SEM armed with EDX probe. Electrochemical impedance spectroscopy was employed as well to define the electron transfer capability of modified and bare electrodes. Key experimental and instrumental conditions related to electrochemical determination by cyclic, differential pulse, and square wave voltammetry, such as amount of modifier, pH, scan rate, accumulation time and potential were studied and optimized. The results have shown a significant enhancement of the peak current after modifying the electrode; the calibration curves of PPF offering good linearity from 0.1 to 10 mu M, limit of quantification (LOQ) being 0.03 mu M and limit of detection (LOD) 0.01 mu M, both when using DPV technique. The proposed sensor was successfully applied to the determination of PFF in dosage form without any special purification, separation or pre-treatment steps. The results of analyses obtained with the proposed sensor were satisfactory and fully statistically relevant. (C) 2019 Elsevier B.V. All rights reserved. Faculty of Chemical Technology, University of Pardubice; Faculty of Pharmacy, Ankara University Financial support from the Faculty of Chemical Technology, University of Pardubice and from Faculty of Pharmacy, Ankara University are gratefully acknowledged. WOS:000479328000062 2-s2.0-85067806253 PubMed: 31252310

Highly sensitive nanosensors such as graphene oxide/ platinum-iridium nanohybrid, carboxylic acid functionalized multiwalled carbon nanotubes (GO/Pt-Ir/MWCNT-COOH) and amine functionalized multiwalled carbon nanotubes (GO/Pt-Ir/MWCNT-NH2) modified glassy carbon electrode were developed for the determination of 5-hydroxytryptamine receptor agonist, Eletriptan. Graphene oxide/platinum-iridium nanohybrid was synthesized using sonication method and then characterized by spectroscopic and microscopic methods such as Raman, TEM, HRTEM, XPS, and XRD. The prepared nanohybrids modified on glassy carbon electrodes were well characterized and applied for electrochemical determination of Eletriptan. The significant enhancement of the oxidation peak current of Eletriptan was observed in GO/Pt-Ir/MWCNT-COOH as a best nanosensor in all prepared ones. The pH, scan rate and the amount of GO/Pt-Ir/MWCNT-COOH were also optimized for Eletriptan analysis. After obtaining of the optimum conditions, the identification of Eletriptan was performed between the linear range of 1 x 10(-7) M and 4 x 10(-6) M with a detection limit of 6.1 x 10(-9) M. The developed method was successfully applied for the determination of the drug in tablets with acceptable recoveries. Moreover, it can be elicited that, in electrochemical studies, electroactive interferences from the tablet excipients did not interfere with the results. (C) 2019 Elsevier B.V. All rights reserved. WOS:000479328000024 2-s2.0-85066622347 PubMed: 31176930

The major goal of this study was to determine the affinity pattern of brombuterol (BB) enantiomers toward various cyclodextrins (CD) and to evaluate the potential of NMR spectroscopy for understanding fine mechanisms of interactions between CDs and BB enantiomers. Separation of BB enantiomers was performed in a fused-silica capillary using a phosphate buffer, pH 2.5, at the room temperature in the normal polarity mode. It was shown once again that CE in combination with NMR spectroscopy represents a very sensitive tool for studies of affinity patterns and structure of CD complexes with chiral guests. Although opposite affinity patterns of BB enantiomers were observed toward native β- and γ-CDs, no significant differences between the structures of the complexes of these two CDs with BB were detected by NMR spectroscopy. In contrary to this, the opposite affinity pattern of BB enantiomers toward β-CD and its two sulfated derivatives, heptakis (2,3-O-diacetyl-6-sulfo)-β-CD (HDAS-β-CD) and heptakis (2-O-methyl-3,6-di-O-sulfo)-β-CD (HMDS-β-CD) was associated with major differences in the structure of the complexes. In addition, it was shown again that HMDS-β-CD provides separation of enantiomers without formation of inclusion-type complex with the chiral analyte.

Molecular imprinting is a method used to prepare synthetic polymers with selective recognition sites for the molecule of interest. For drug analyses, the molecularly imprinted polymer (MIP) should have high specificity toward one substance in order to allow for fingerprinting. Because the majority of drugs act as inhibitors of enzymes, antagonists of chemoreceptors, and binders to nucleic acids, the MIPs should mimic their binding pockets. In this way, drugs can be analyzed using the binding–rebinding strategy of the MIP-based nanosensor. In addition to low-molecular-weight drugs, MIPs have been synthesized for peptides and protein biomarkers, including enzymes and nucleic acids. Modifications of the surface of the transducer by nanomaterials exploit the unique physical and chemical properties in order to improve the analytical performance of the biomimetic sensors. Metal-based nanomaterials, such as gold, platinum, and silver, or carbon-based nanomaterials, or inorganic nanomaterials, such as titanium dioxide, are the most common nanomaterials for the design of nanosensors based on molecularly imprinted polymers. In this chapter, nanosensor design using molecularly imprinted polymers is discussed in detail. Moreover, the application of nanomaterials-modified MIPs for pharmaceutical analysis are presented.

The signals at the electrode-solution interface of an electrochemical nanosensor may either be dynamic or static. For dynamic methods, such as amperometric-based nanosensors that measure current proportional to the concentration of the analyte, the electroactive center of the species transfers electrons through a redox reaction at the working electrode, while in static methods the potentiometric mode of operation is followed in which charged species are involved. Nanoparticles and semiconductors have been shown to enhance the catalytic properties of analytical reactions by decreasing the overpotential of the reaction and facilitating faster electron transfer reactions, even conferring reversibility to some reactions reported to be irreversible at the unmodified electrode surfaces. Because all analytes are not intrinsically capable of serving as redox partners in electrochemical reactions, so mediators are used in these devices for facilitating the electrochemical reaction of the analytes at the electrode surface. The current chapter presents an overview of nanomaterials that affect sensing performance. Due to the attractive properties of materials at nanoscale dimensions, medical and pharmaceutical nanotechnology has become one of the most fascinating research topics in the fabrication and development of nanobiosensors. The morphology, geometric shape, and structural dimensions of materials at the nanoscale provide several advantages, which significantly influence the transduction ability of nanomaterial-modified electrodes.

Many of the recent developments in optical nanosensors have led to tuning the analytical performance of these devices to physiological concentration ranges. Optical nanosensors that measure amplitude, energy, polarization, decay time and decay phase of absorption, phosphorescence, fluorescence, Raman scattering, refraction, interference, and dispersion are extensively used for the detection of pharmaceuticals. The use of highly selective and sensitive nanomaterials-based optical sensors for the detection of disease biomarkers has maximized the chances of early-stage diagnosis of various diseases. Optical nanosensors have attracted a lot of interest for quantifying and measuring disease biomarkers, small molecule proteins, and peptides, as well as for ion concentrations and drug detection. This chapter covers the recent advances in terms of fiber optic-based plasmonic nanosensors along with optical spectroscopy, such as luminescence or colorimetric spectroscopy, and their applications in pharmaceuticals and medicinal biology.

In this study, a novel and sensitive voltammetric nanosensor has been developed for the first time, for the detection of Rilpivirine based on amine-functionalized multiwalled carbon nanotubes (NH 2 -fMWCNT) with Ag nanoparticles onto carbon quantum dots modified glassy carbon electrode. Scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were employed for characterization of the modified electrode. The Rilpivirine showed two irreversible oxidation peaks at 1.20 V and 1.42 V, at all the investigated pH values. The cyclic voltammetry results demonstrated excellent electrocatalytic activity of the modified electrode toward the oxidation of Rilpivirine as endorsed by the enhanced current responses compared to bare electrode. The electrochemical catalytic activity was further utilized as a sensitive detection method for the investigation of the redox mechanism of Rilpivirine using differential pulse voltammetry (DPV). For experimental conditions optimization the influence of supporting electrolyte and pH was examined and 0.5 M H 2 SO 4 was selected as the best electrolyte for getting intense current signals of the target analyte. The relationship of anodic peaks potentials for peak 1 and peak 2 (E P1 and E P2 ) with pH values and scan rate was also studied. Scan rate results showed that the oxidation of Rilpivirine at the nanosensor surface occurs under adsorption controlled manner. Therefore, differential pulse adsorptive stripping voltammetric technique was employed for the determination of Rilpivirine. Optimum accumulation potential and time were found as 0 V and 60 s, respectively. Under these optimum conditions, response of Rilpivirine demonstrated a linear behavior in the concentration range from 1.00 × 10 ?9 to 7.00 × 10 -9 M, with a limit of detection value of 3.00 × 10 -11 M and 6.40 × 10 -11 M for peak 1 and peak 2 in aqueous medium containing 0.5 M H 2 SO 4 as supporting electrolyte, respectively. Interferences studies were achieved in the presence of 500 fold higher concentration of interfering agents to check the selectivity of the developed method. The designed method was successfully applied for the determination of Rilpivirine in biological fluids, urine and synthetic human serum as a real sample. The value of limit of detection were found to be 1.79 × 10 -10 M, 4.47 × 10 -10 M in serum samples, 5.26 × 10 -10 M and 8.27 × 10 -10 M in urine samples for peak 1 and peak 2, respectively. Recovery experiments were carried out to check the accuracy and precision of the designed method. Moreover, the repeatability, reproducibility and stability of the modified electrode in supporting electrolyte, serum and urine samples were investigated. © 2019 Elsevier B.V.

Noble metals are resistant to corrosion and oxidation in moist air. Ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold are a list of noble metals, in order of their respective atomic numbers. The unique characteristics of noble metal nanoparticles (NPs), such as high surface-to-volume ratio, broad optical properties, ease of synthesis, and facile surface chemistry and functionalization, guarantees advantages in drug analysis. The most used NPs are gold (Au) and silver (Ag) due to their electrical, chemical, optical, and other unique properties. Electrochemical methods have proven to be sensitive and reliable for the determination of numerous electroactive compounds. Under certain circumstances, electrochemical methods can offer optimal solutions for drug analysis. Simplicity, low cost, and relatively short analysis times make electrochemical techniques more useful for routine analytical applications. In this chapter, NPs and their various applications in electrochemical drug analysis are presented.

Erlotinib (ERL) is a tyrosine kinase inhibitor which prevents growing of cancer cells. The electrochemical oxidation mechanism of ERL was studied in details using cyclic voltammetry. Cyclic voltammetry, differential pulse and square wave voltammetric techniques were applied for sensitive, fast, precise determination of ERL. Adsorptive stripping square wave voltammetry was selected and applied to the assay of ERL in pharmaceutical dosage forms. Quantitative application and its validation were realized via ?-Cyclodextrin nanoparticles modified glassy carbon electrode in 0.1 M phosphate buffer pH 3.0 in the presence of 20% methanol. The adsorptive stripping square wave voltammetry provided linear response within the concentration ranges 1.00 × 10?8 M - 8.00 × 10-6 M (r = 0.999) with LOD and LOQ values 1.07 × 10-9 M and 3.58 × 10-9 M, respectively. The recovery of erlotinib in Tarceva® tablets was 100.38%. In addition, computational studies were exerted to complement to the analytical studies, The molecular electrostatic potential surface and frontier molecular orbitals have been calculated at the DFT level and on B3LYP/6?31+G* to elucidate the ERL oxidation behavior. The results shown that the theoretical data were consistent with the proposed oxidation mechanism of ERL. © 2018 Elsevier B.V. 2-s2.0-85054092809

Nanotechnology is an expanding field, especially in engineering, physics, chemistry, biology, and medicine. Nanotechnology is unique in that it signifies not a single specific area, but a vast variety of disciplines ranging from basic material science to personal care applications. The application of nanotechnology to drug delivery is commonly expected to change the landscape of the drug and biotechnology industries for the foreseeable future. Moreover, nano-sized drug delivery systems have already had a great impact on pharmaceutical technology by improving the effect of drugs and enabling new therapies. Nanoparticles used in drug delivery are nano-sized in at least one dimension and consist of different materials. Based on the application of the preparations, there are varied forms of nanoparticles that have been synthesized and evaluated to improve drug bioavailability, overcome drug resistance, and reduce drug toxicity. To achieve effective drug delivery, it is essential to understand the biological environment–nanoparticle interaction, drug release from nanoparticles, multiple drug administration, and the stability of therapeutic agents and molecular mechanisms of cell behavior in the disease under consideration. Due to their tremendous properties, nanoparticles have been utilized to treat a variety of diseases and disorders by their attachment to biologically active molecules, targeting sequences, fluorescent or other imaging devices, biocompatible coatings, and others.

Nanosensors have improved very quickly in the last decades and their roles have greatly expanded within the pharmaceutical and biomedical fields, in which measurement science and technology are of key importance. The enhanced chemical and physical properties arising from discrete nanoelectrode devices or the modification of the electrode surface with nanomaterials make these devices an attractive option for the improvement of current analytical applications in the pharmaceutical area because of their excellent sensitivity. Chemical nanosensors can be designed using carbon-based (fullerene carbon nanotubes, graphene, nanodiamond, etc.), polymer-based, or metal-based (gold, silver, platinum nanoparticles, etc.) nanomaterials. Chemical nanosensors are generally used to detect various chemicals in monitoring pollution, in drugs, in residue from environmental samples, and for the assay of organophosphorus compounds. Moreover, chemical nanosensors are also used for diagnostic purposes. A transducer, such as an electrochemical, optical, thermal, or piezoelectric transducer, combined with the sensor is used in chemical nanosensors for pharmaceutical analysis. This chapter is focused on chemical nanosensors and their applications in pharmaceutical analysis with different types of samples.

Sensors are devices that detect a physical, chemical, or biological stimulus and give a response in the form of a measurable signal. The increasing number of applications for sensing technologies has increased the need for the development of a variety of new sensors with far better performance. Nanoparticles are at the forefront in the fabrication of high-throughput nanosensors for applications ranging from pharmaceuticals to signature nano-based platforms that profile different therapeutic drugs, selective chemicals, and bioassays to environmental analysis by modifying the surface of the electrode for electrochemical detection, offering high sensitivity and selectivity. In this chapter, we will discuss the sensing enhancement impact of a number of nanoparticles, including metals, oxides, and semiconductor-based nanoparticles, mostly employing carbon-based nanoparticles (CNTs, graphene, fullerenes, carbon nanodots, nanowires, and nanodiamonds), dendrimers, and composite nanoparticles on multiple sensors, such as electrochemical, optical, and photoelectrochemical sensors. Moreover, this chapter will offer an introduction to recent developments in the design of nanosensors for trace-level multidrug detection with reproducible results. The ability of electrodes modified with nanomaterials for multianalyte screening and rapid toxicity testing will also be discussed. Moreover, owing to the unique oxidation or reduction potential of every drug, the selectivity of electrochemical sensing platforms based on nanomaterials for the detection of drugs and their metabolites will be highlighted.

Over the last decades, increasing consumer awareness of relation between health and plant products has driven the functional and medicinal beverages industry to put much effort into products with botanically fortified ingredients. The addition of botanical products requires high-level knowledge of chemistry to prevent the interactions and safety problems. Analyses of functional beverages and medicinal beverages with botanical products can be achieved through different kinds of analytical methods such as electrochemical, chromatographic, spectrophotometric, etc. This chapter focuses on the functional and medicinal beverages fortified by the botanical substances and their potential health benefits. Moreover, in this chapter, recent studies were summarized from the viewpoint of analysis conditions, sample preparation, and validation parameters.

DNA nanotechnology is an effective tool to combine DNA with nanomaterials for the fabrication of various nanoscale devices and nanostructures with potential performance in drug delivery and their biosensing assay. The development of DNA nanotechnologies, such as DNA nanomachines as smart carriers has been attracting increasing attention due to their small sizes, predictable secondary structures, and high biocompatibility. DNA-based nanomachines can be attached to other nanomodalities, such as polymers, gold nanomotors, and carbon nanostructures to create hybrid delivery structures. In the current review, we summarize the recent advances in the development of DNA nanotechnology to build functional and smart nanomachines and the bioapplication of this technology in electrochemical biosensing, immunosensing, and drug delivery.

Electropolymerization of aniline on suitably roughened gold electrodes enabled us to record in situ surface-enhanced Raman scattering (SERS) spectra of polyaniline (PAni) during the doping-undoping process. Indeed, SERS-activation pretreatment of gold working electrode, using a specific electrochemical oxidation-reduction procedure, leads to the formation of countless surface asperities. The intergranular sites, known as “hot spots”, thus generated by the surface roughness are the seat of a strong electromagnetic coupling which leads to a huge SERS effect. Contrary to the case of platinum or mirror-polished gold electrodes, the use of roughened gold leads to high quality in situ SERS spectra of PAni, allowing the observation of important changes in the spectral features of its different oxidation states. In this study, we relied on spectral decomposition procedures to monitor and try to quantify these transformations accompanying the variation in the oxidation state of the polymer in different acidic aqueous solutions. In particular, the transition between the different forms of PAni (leucoemeraldine → emeraldine → pernigraniline), the drastic passage from benzenoid to quinoid structures of some aniline nuclei and the evolution of the charge-carrying structural defects are investigated despite the limitations imposed by the challenging conditions of the in situ analysis.

The endocrine system that provides communication and maintains homeostasis, is an important part of the body. Any defects or disruptions that affect the endocrine system may cause serious problems in the actions and functions of the body. Endocrine disruptive chemicals (EDCs) are exogenous chemicals or mixtures of chemicals that affects normal functions of the endocrine system by interfering with endogenous hormones and hormonal pathways and disrupting homeostasis. Numerous compounds are considered as endocrine disruptors such as bisphenols (BPs), phthalates, pesticides etc. and they are widely used for industrial purposes in many commercial products. Therefore, human exposure is almost inevitable. Besides that, EDCs may cause environmental pollution and are found in surface waters, wastewater, soil etc. To prevent exposure and hazardous effect, there are legislative regulations including restrictions and prohibitions of the use of EDCs. Due to these reasons; it is crucial to develop highly sensitive, low-cost, easy-to-use, and rapid sensors for the determination of EDCs in commercial and environmental samples. Although there are mostly chromatographic and spectrometric methods for the EDCs monitoring, electrochemistry surpasses them with advantageous properties such as easy application procedure, high sensitivity, very low limit of detection (LOD) values and low-cost. In this review, major groups of EDCs will be explained with their recent and novel electrochemical sensor applications for their detection in commercial and environmental samples.

Trimetazidine hydrochloride (TMZ), well-known by its unique and interesting pharmacological properties, has been investigated by several electrochemical techniques using Poly(3,4-ethylenedioxythiophene) coated glassy carbon electrode (GCE). The preparation of the modified electrode was achieved by the electrodeposition of PEDOT in two different media and the obtained film has been characterized by scanning electron microscopy (SEM) and infrared spectroscopy (FTIR). The electrochemical analysis of TMZ was then studied by cyclic, differential pulse and square wave voltammetric methods in solutions of different pH values and results have shown that square wave voltammetry (SWV) is the most suitable one for the analytical characterization. The oxidation of TMZ was irreversible and was a process under diffusion control. Besides, Model compounds and molecules were also used in this study to describe the possible oxidation mechanism of TMZ. In this contribution, the main objective is the possible practical use of the proposed method, thus, the electrochemical detection of TMZ by SWV was carried out in biological samples, such as human serum and urine. Under the optimum condition in phosphate buffer at pH 3.0, linear calibration curves were obtained for all studied media (supporting electrolyte, urine and serum). Important parameters, namely, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ) were reported, and good sensitivity, reproducibility and repeatability were obtained. Furthermore, recovery values of almost 100% were found for pharmaceuticals and biological samples, suggesting that the sensor can be used in practical applications.

Surfactants play an important role in preparation of nanoparticles. In this study, it was aimed to investigate the effect of surfactant type and concentration on development of epirubicin loaded Poly ( d , l -lactide-coglycolide acid) (PLGA) nanoparticles. In this regard PVA, TPGS, sodium cholate and Poloxamer 188 were used as surfactants to prepare epirubicin loaded PLGA nanoparticles in three concentrations. It was found that the particle size of nanoparticles was varied in the range 109.6 ± 5.19 nm and 511.5 ± 23.99 nm. The size of nanoparticles was smaller when sodium cholate was used (p

In this study separation of enantiomers of 8 chiral ?-agonists were studied on 6 polysaccharide-based chiral columns in polar-organic and alcohol-hydrocarbon mobile phases. No separation of enantiomers was observed on any column with polar-organic mobile phase eluents such as pure methanol, ethanol or acetonitrile. Most of the chiral analytes were resolved into enantiomers when alcohol-hydrocarbon type mobile phases were used. The most successful column was Lux Cellulose-2 on which all 8 chiral analytes were baseline resolved into enantiomers at least with one mobile phase used. The reversal of enantiomer elution order was observed dependent on the chemistry of the chiral selector and the composition of the mobile phase. © 2016 Elsevier B.V.

In the present work, the electrochemical oxidation of a new generation of anticancer drug, imatinib ( Ima ), using differential pulse voltammetry (DPV) on anodically pretreated boron doped diamond electrode (BDDE) has been reported. The results of a study showed that Ima provided well-shaped oxidation peak at positive potential of around + 1.0 V ( vs. Ag/AgCl/KCl) in the Britton–Robinson (B–R) buffer at pH 2.0. The experimental conditions, i.e. pH, a modulation amplitude, a modulation time, a step potential, and a scan rate, were optimized. A simple, rapid, selective and sensitive DPV procedure for the determination of Ima was performed in the concentration range of 3.0 × 10 − 8 –2.5 × 10 − 7 mol L − 1 with the limit of detection ( LOD ) and the limit of quantification ( LOQ ) of 6.3 × 10 − 9 mol L − 1 and 2.1 × 10 − 8 mol L − 1 , respectively. The proposed methodology with using an anodic signal of imatinib at BDDE shown comparable detection limit as for hanging mercury drop electrode in the determination of this anticancer drug. A biological significance of the developed DPV procedure was demonstrated by a quantitative analysis of the spiked human urine samples with satisfactory recoveries (from 102.2% to 105.5%). Additionally, the influence of some interfering compounds and ions ( Int ) was also evaluated. The cyclic voltammetry (CV) was used for the investigation of the electrooxidation mechanism of Ima . The developed approach could be beneficial in analysis of imatinib in biological samples using BDDE as up-to-date electrochemical sensor and could represent non-toxic analytical alternative to HMDE.

A sensitive, simple, rapid, experimentally convenient, cost-effective, environmentally friendly and high-throughput green chemistry by capillary electrophoresis (CE) approach for the determination of eight polyphenolics frequently found in red wines from USA was carried without using toxic organic modifier. Several parameters which affect the separation were investigated to determine the optimum conditions. At room temperature, the eight polyphenolics could be well separated within 15 min in a 55-cm length capillary at a separation voltage of 26 kV with 40-mM borate buffer (pH 8.9). The method was fully validated showing satisfactory data for all method validation parameters tested. The limits of detection varied from 0.15 to 0.32 µM. The relative standard deviations of migration varied from 0.208 to 0.630 %. The Californian red wine samples analyzed were bought in the local markets, and the polyphenolic compound recoveries were in the range of 98–99.7 %. The method was successfully applied to the determination of the studied polyphenolics in red wine samples with satisfactory recoveries. Catechin, syringic acid, apigenin, myricetin, luteolin, quercetin, caffeic acid, and gallic acid were detected in all samples, with gallic acid and myricetin occurring in the highest concentration. © 2016, Springer-Verlag Berlin Heidelberg.

Studying the process of interaction between DNA and drugs became widespread in last more than ten years. In this regard, designing electrochemical DNA biosensors contributed to the development of more selective and sensitive electrochemical methods for the detection of specific DNA binding. This paper is based on the researches in the last years (between 2004 and 2015) focusing on the studies on electroanalytical interactions between dsDNA and drugs. Normal pulse, cyclic, differential pulse and square wave voltammetric methods were generally employed for analyzing drug and dsDNA oxidation signals through using various sensors and nanosensors. The researches on these fields are summarized as tables providing information about pH and medium of the study, sensor/nanosensor type, modes of mechanism and binding constant of drug-dsDNA interaction, the results expressed in the concentration range and also detection limits.

The i-E oxidation curves, obtained using a boron doped diamond electrode, for studies of oxidations of two piperazine derivatives ARIP (I) and PIRI (II), resulted in a sharp increase of current in the range of the oxidation potentials. After reaching a value, depending on concentration of I or II, the current remains practically constant up to +1.6 V. Such limiting currents i1 are a linear function of concentrations and depend on the v1/2. Hence it is diffusion controlled, shifts of the oxidation potentials indicate, that the monoprotonated forms are oxidized. At more negative potentials a limiting current i2 occurs, due to the oxidation of the diprotonated form. Current i2 increases with decreasing pH in a shape of a part of a dissociation curve. Diffusion control reflects the large size of molecules I and II. The two-electron oxidations yield a C=N bond in the piperazine ring. It seems to be the first reported diffusion controlled oxidation curves obtained on a stationary solid electrode.

In the proposed work, the simultaneous analysis of amlodipine–rosuvastatin and amlodipine–atorvastatin in their dosage forms was achieved. Simultaneous dissolution profiles of the amlodipine–rosuvastatin and amlodipine–atorvastatin tablets are realized using Apparatus II with a simple, accurate and precise RP-LC method. The mobile phase consisting of 0.2 % H3PO4 and pH 5:methanol:acetonitrile (46:27:27) was used. The samples of 10 µL were injected onto a Zorbax SB C18 (100 mm, 4.6 mm, 3.5 µm particle size) column with 1.2 µL min−1 flow rate. The samples were detected at 236 nm. By plotting peak area ratios vs. concentration, the linearity for amlodipine–rosuvastatin and amlodipine–atorvastatin was determined. With the developed RP-LC method, AML, ROS and ATOR were detected within the range of 0.25–10, 0.5–10 and 0.25–25 µg mL−1, respectively. LOD and LOQ values were also calculated as 0.028, 0.058, 0.021 and 0.095 µg mL−1, 0.195 µg mL−1, 0.070 µg mL−1 for AML, ROS and ATOR, respectively. System suitability tests parameters, such as capacity factor, selectivity to previous peak, selectivity to next peak, resolution to previous peak, resolution to next peak, tailing factor, theoretical number of plates, were performed and found coherent with the ICH guideline parameters. The proposed method has been extensively validated in terms of recovery, and recovery results were between 99 and 101 %. For proving the precision, between-day and within-day repeatability results of the method were proposed. The method can be used for the simultaneous determination of amlodipine–rosuvastatin and amlodipine–atorvastatin.

Capillary electrophoretic (CE) and high performance liquid chromatographic (HPLC) methods were developed and optimized for the determination of antazoline (ANT) and tetrahydrozoline (TET) in ophthalmic formulations. Optimum electrophoretic conditions were achieved using a background electrolyte of 20mM phosphate buffer at pH 7.0, a capillary temperature of 25°C, a separation voltage of 22 kV and a pressure injection of the sample at 50 mbar for 17s. HPLC analysis was performed with Kinetex (150 × 4.6mm ID × 5 μm) (Phenomenex, USA) analytical column with 1 mL min(-1) flow rate of mobile phase which consisted of 0.05% TFA in bidistilled water (pH adjusted to 3.0 with 5M NaOH) and acetonitrile/buffer in the ratio of 63:37 (v/v) at room temperature. Injection volume of the samples was 10 μL and the wavelength of the detector was set at 215 nm for monitoring both analytes. Calibration graphs showed a good linearity with a coefficient of determination (R(2)) of at least 0.998 for both methods. Intraday and interday precision (expressed as RSD%) were lower than 2.8% for CE and 0.92% for HPLC. The developed methods were demonstrated to be simple and rapid for the determination of ANT and TET in ophthalmic solutions providing recoveries in the range between 97.9 and 102.70% for CE and HPLC.

An electrochemical nanosensor for monitoring zafirlukast (ZAF) concentration in biological fluids was developed by the modification of the glassy carbon electrode (GCE) surface via layer-by-layer approach. The GCE surface was first modified with amine-functionalized multi-walled carbon nanotubes (NH2–fMWCNTs), and then sodium dodecylsulfate doped over-oxidized polypyrrole film (SDS-ooPPy) was electrosynthesized on the NH2–fMWCNTs/GCE. The morphology and characterization of prepared nanosensor were done by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The developed sensor has an excellent electrocatalytic activity towards the oxidation of ZAF, resulting in enhancing the electrochemical response, due to the synergistic effect between NH2–fMWCNTs and SDS-ooPPy and more negative charge density of ooPpy on a 1D structure of NH2–fMWCNTs. The parameters affecting the electrochemical behavior of ZAF including pH, the amount of NH2–fMWCNTs, the concentration of SDS and pyrrole (Py) monomer, and the number of cycles required in the electropolymerization step for the modification of electrode were optimized. The redox mechanism pathway for the electro-oxidation of ZAF and the thermodynamic study was performed by CV. The calibration graph of ZAF determination by square wave voltammetry (SWV) under the optimized condition using SDS–ooPPy/NH2–fMWCNTs/GCE provided a linear range of 1.0 × 10−7 M to 1.0 × 10−5 M. The sensitivity of 4442 μA mM−1 cm−2 and a LOD of 20.0 nM (S/N = 3) were obtained. Finally, the proposed nanosensor was used successfully for monitoring of ZAF in biological fluids with acceptable recovery data.

Quantum dots (QDs), nano-sized semiconductors, are one of the most important materials that create a bridge between nanotechnology, and drug assay. Their unique photoluminescence and electronic properties including broad and continuous absorption spectra, narrow emission spectra from visible to near-infrared wavelengths, long light lasting, high brightness make them as some suitable probe materials in (bio)sensing or immunosensing platform. Quantum dots (QDs) are considered efficient fluorescent labels used in a drug delivery system for monitoring the metabolism process of drugs in the body owing to the unique physicochemical characteristics. They can also be developed for a variety of biomedical applications, such as disease detection, and fluorescent assays for drug discovery. This paper reviews the physical and chemical properties of QDs, their synthesis methods, surface modification and bioconjugation as well as some interesting examples of their recent applications in analytical chemistry, drug delivery, biosensing and immunoassay.

In this work, a novel electrochemical molecularly imprinted polymer (MIP) sensor for the detection of the lipopeptide antibiotic Daptomycin (DAP) is presented which integrates gold decorated platinum nanoparticles (Au-Pt NPs) into the nanocomposite film. The sensor was prepared by electropolymerization of o-phenylenediamine (o-PD) in the presence of DAP using cyclic voltammetry. Cyclic voltammetry and differential pulse voltammetry were applied to follow the changes in the MIP-layer related to rebinding and removal of the target DAP by using the redox marker [Fe(CN)(6)](3-/4-). Under optimized operational conditions, the MIP/Au-Pt NPs/ GCE nanosensor exhibits a linear response in the range of 1-20 pM towards DAP. The limit of detection and limit of quantification were determined to be 0.161pM +/- 0.012 and 0.489pM +/- 0.012, respectively. The sensitivity towards the antibiotics Vancomycin and Erythromycin and the amino acids glycine and tryptophan was below 7 percent as compared with DAP. Moreover, the nanosensor was also successfully used for the detection of DAP in deproteinated human serum samples.

A new molecularly imprinting polymer (MIP) based sensor was developed for the selective detection of pemetrexed (PMX) by the electropolymerization of ortho phenylenediammine (o-PD) on carbon quantum dot modified screen printed carbon electrode (CQD/SPCE). The surface characterization was performed with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The conditions such as casting amount of CQD, incubation time, removal time for successful polymerization were tested. The selectivity of developed sensor also tested with similar compounds with PMX. The results showed that the developed sensor could achieve to detection of PMX from synthetic serum sample with high recovery 99.3%. From the computational perspective of view, PMX was also optimized at B3LYP/6-311 G∗//DFT level using the Gaussian 09 program package. Molecular electrostatic potential surface (MESP) was performed to investigate effects of the electronic and structure properties of PMX.

In this study, a novel carbon electrode material for improved electrochemical sensing of vardenafil (VRF) as a model drug active substance was prepared by two cycled hydrothermal carbonization (HTC) of algae-based biomass for the first time in open literature. In order to increase the electrical conductivity more, multi-walled carbon nanotube (MWCNT) was used as a catalyst during the second cycle of HTC. The surface morphology and chemical structure of the synthesized carbonaceous materials were investigated by using different techniques. The voltammetric behaviour of VRF drug was investigated on glassy carbon electrode (GCE) modified by algae based carbon electrode material. MWCNT catalyzed carbon material obtained from second cycle of HTC treatment exhibited more sensitive, reproducible and low oxidation potential comparing to bare GCE in the presence of VRF due to the increased degree of graphitization. At the optimum conditions, differential pulse voltamograms (DPV) method with MWCNT catalyzed carbon material exhibited high sensitivity with the detection limits of 96.3 pM at pH 1.0 H2SO4 solution, 60.6 nM at serum and 46.7 nM at urine samples. Finally, the proposed sensor was successfully applied in tablet formulation, human serum and human urine samples.

An electrochemical sensor is described for the determination of nadifloxacin (NF). A glassy carbon electrode (GCE) was modified with amino-functionalized multiwalled carbon nanotubes and titanium dioxide nanoparticles. The modified GCE was characterized by electrochemical impedance spectroscopy, cyclic voltammetry and scanning electron microscopy. The electro-oxidation of NF follows a pH-dependent irreversible behavior. The effects of pH value, scan rate, supporting electrolyte, accumulation potential and accumulation time were optimized. Under optimum conditions and at a typical working potential of 600 mV (vs. Ag/AgCl), the adsorptive stripping voltammetric response is linear in the 5 nM to 5.0 μM NF concentration range. The limit of detection is 1.69 × 10−10 M in acidic solution of pH 1. The selectivity was investigated in the presence of 1–1000-fold concentrations of potentially interfering agents. Recoveries from cream formulations spiked with NF were performed to study precision and accuracy.

A novel electrochemical sensor for the sensitive determination of catechol was developed based on the layer-by layer modification of the glassy carbon electrode surface with a copper metal organic framework (Cu-MOF), ZnTe nanorods (ZnTe NRs) and Au nanoparticles (Au NPs). ZnTe nanorods and Au nanoparticles were incorporated into a copper metal organic framework for the modification of glassy carbon electrode. Characterization of synthesized materials was performed by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), FT-IR, X-ray diffraction (XRD), and electrochemical techniques. The composite electrode exhibited an excellent electrocatalytic activity with enhanced electrochemical response towards the oxidation of catechol, due to the synergistic effect of Cu-MOF/ZnTe NRs and Au nanoparticles. The effects of some parameters on the catechol response such as the amount of Cu-MOF/ZnTe NRs and Au NPs, pH, and scan rate were studied and optimized. The mechanism for electrochemical reaction of catechol was suggested as an ErCr pathway. Under the optimized condition, the calibration graph for catechol constructed using DPV technique at Cu-MOF/ZnTe NRs/AuNPs/GCE showed the linear range from 2.5 × 10−7 M to 3 × 10−4 M with a sensitivity of 142.03 μA mM−1 and a calculated detection limit of 16 nM (S/N = 3). The developed sensor was successfully applied for the determination of catechol and its derivatives in the pharmaceuticals, wastewater, well water, tap water, tea samples, and in biological fluids with satisfactory recovery data.

This study presents evaluation of the possible interaction mechanism between calf thymus dsDNA and three calcium antagonists; nifedipine, lercanidipine and amlodipine. The interactions between Nifedipine-dsDNA and Lercanidipine-dsDNA were investigated by differential pulse voltammetry using two different interaction methods; at the dsDNA-electrochemical biosensor surface and in bulk incubated solution. Amlodipine was used as model drug in bulk incubated solution. The decrease in the peak current of guanine and adenine were used as an indicator for confirmation of the interaction event in acetate buffer of pH 4.70. In bulk incubated solution, after interaction with Nifedipine and Amlodipine the guanine signal was almost disappeared. At the dsDNA modified glassy carbon electrode surface, the peak currents of guanine and adenine were decreased while Nifedipine and Lercanidipine interacts with DNA. The interactions between Nifedipine-dsDNA and Lercanidipine-dsDNA were further studied by UV–Vis absorption spectroscopy which indicates the intermolecular interaction between these drugs and ds-DNA can be mainly through hydrogen bonding and van der Waals forces. Molecular docking calculations shown that the AMP-1-2, NDP and LDP-1-2-ctDNA having groove binding. Beside spectral data, docking studies elicited that AMP-1-2, NDP and LDP-1-2 complexes have different interaction and conformation trends to target (ctDNA).

In this study, an antiparkinson drug Entacapone (ENP) is electrochemically investigated under optimized conditions using NH

Cardiovascular disease is the most reason for deaths in all over the world. Hence, biomarkers of cardiovascular diseases are very crucial for diagnosis and management process. Biomarker detection demand is opened the important way in biosensor development field. Rapid, cheap, portable, precise, selective and sensitive biomarker sensing devices are needed at this point to detect and predict disease. A cardiac biomarker can be orderable as C-reactive protein, troponin I or T, myoglobin, tumor necrosis factor alpha, interleukin-6, interleukin-1, lipoprotein-associated phospholipase, low-density lipoprotein and myeloperoxidase. They are used for prediction of cardiovascular diseases. There are many methods for early diagnosis of cardiovascular diseases, but these have long time process and expensive devices. In recent studies, different biosensors have been developed to remove the problems in this field. Electrochemical devices and developed biosensors have many superiorities than others such as low cost, mobile, reliable, repeatable, need a little amount of solution. In this review, recent studies were presented as details for cardiovascular disease biomarkers detection using electrochemical methods.