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Background: Electrochemical methods in drug analysis have a lot of advantages, including simplicity, speed, low-cost instrumentation, informing about the drug mechanism, and nonaffection by excipients in dosage forms. Electrochemical techniques utilize the advantages of nanomaterials to increase sensitivity and, in some cases, selectivity. Among these nanomaterials, metal oxide nanoparticles are also preferred by researchers because of their unique properties such as biocompatibility, stability, non-toxicity, and catalytic characteristic. Objective: This review provided brief information about metal oxide nanoparticles used in electrochemical sensors and summarized applications for drug analysis with these sensors in tables showing the studies in the literature during the last decade. Results: In the last decade, metal oxides are frequently used in electrochemical drug analysis as electrode modifier individually and with other nanomaterials especially carbon-based ones. All these studies showed that metal oxide nanoparticles increase the active surface area of the electrode and the catalytic activity. Conclusion: When metal oxide nanoparticles and carbon-based nanomaterials are used together, they create a synergistic effect that further increases catalytic activity and thus lowers detection limits to be obtained in nM even pM levels.

Background In the near future, sensitive, rapid and economical detection of food allergens will remain a hardship to the health promotion of the community. Biogenic Amines (BAs) are a type of food allergens, and due to the trace level and complexity of BAs, improvement of professional and cost-effective detection techniques has become particularly demanding. Since vegetables, canned and fresh fish, beverages, and fermented foods have high concentrations of BAs and are mainly consumed, the advancement of specific and finely tuned methods for quick diagnosis of BAs are exceedingly urgent. Scope and approach In this review, enzyme-based biosensors for BAs detection in foods with different transducers such as chemiluminescent, surface-enhanced raman scattering biosensors electrochemical, and fluorescence biosensors are presented. Nanozymes-based detection of BAs in foods are also discussed with recent applications. Moreover, the latest advances of BAs detection by enzyme-based biosensors and nanozyme-based methods are further tabulated. Key findings and conclusion Among modern diagnostic techniques, biosensors are economical, simple, and precise instruments for BAs detection. In the future, studying novel biosensors such as multifunctional nanocomposite biosensors will satisfy the demand for the enhancement of food safety and cost-effective nanozyme-based methods for BAs detection.

Herein, a conjugated polymer and fullerene bearing architecture-based electrochemical Tyrosinase (Tyr) enzyme inhibition biosensor for indomethacin (INDO) drug active compound has been developed. For this purpose, three moieties of benzoxadiazole, thienopyrroledione, and benzodithiophene containing conjugated polymer; poly[BDT-alt-(TP;BO)] was used as a transducer modifier together with fullerene for catechol detection. The specific combination of these materials is considered an effective way to fabricate highly sensitive and fast response catechol biosensors for the first time. Electrochemical and surface characteristics of the modified electrodes were obtained by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, and atomic force microscopy. The effect of the parameters during chronoamperometric measurements on the biosensor response was also studied. Using optimized conditions, biosensing of catechol was achieved between 0.5 and 62.5 µM with a limit of the detection 0.11 µM. Tyr inhibition was followed with INDO drug active compound and it was found that INDO has a mixed type characteristic of enzyme kinetics with an I

Interactive association of an antifungal drug, climbazole (CBZ) with the carrier protein in bovine circulation, bovine serum albumin (BSA) was explored by fluorescence and absorption spectroscopy along with in silico techniques. The fluorescence and absorption spectral alterations of the protein upon addition of CBZ affirmed the complex foration between CBZ and BSA. The inverse temperature dependence behaviour of the K

This study is designed to investigate the interaction of phenylpiperidine derivative drug paroxetine, which is an effective serotonin reuptake inhibitor and biomolecules through electrochemical, fluorescence spectroscopy, and molecular docking methods. The interaction between paroxetine and biomolecules was investigated by differ-ential pulse voltammetry according to the decrease in deoxyguanosine anodic oxidation signal of double -stranded calf thymus DNA. Fluorescence spectroscopy studies were performed by titrating paroxetine against double-stranded calf thymus DNA solution at four different temperatures. The fluorescent results showed that paroxetine had a great affinity to bind with double-stranded calf thymus DNA. Interaction studies demonstrate that paroxetine binds to double-stranded calf thymus DNA via intercalation binding mode, and the binding constant values were calculated as 7.24 x 104 M-1 and 1.52 x 104 M-1 at 25 degrees C, based on voltammetric and spectroscopic results, respectively. Moreover, with the aim of elucidating the interaction mechanism between paroxetine and double-stranded calf thymus DNA, electrochemical and fluorescence spectroscopy studies along with molecular docking analysis were made.

In this study, the interaction between the phosphodiesterase-3 enzyme inhibitor drug milrinone and biomolecules was investigated by electrochemical, fluorescence spectroscopy, and molecular docking studies for the first time. The interaction between milrinone and biomolecules was investigated according to the decrease in deoxyguanosine oxidation signals of milrinone and calf thymus double-stranded deoxyribonucleic acid (ct-dsDNA) by cyclic voltammetry and differential pulse voltammetry. In fluorescence spectroscopy studies, a competitive study was conducted on ct-dsDNA by adding a well-known fluorescent methylene blue and ct-dsDNA solution. The fluorescent results showed that milrinone had a higher affinity for ct-dsDNA binding compared to methylene blue. Interaction studies show that milrinone binds to ct-dsDNA via a groove-binding mode, and the binding constant values ​​were calculated as 4.27 × 106 M−1 and 6.03 × 104 M−1 at 25 °C, based on cyclic voltammetry and spectroscopic results, respectively. As a result of the interaction of human serum albumin and milrinone, the binding coefficient was calculated as 4.11 × 106 M−1 by cyclic voltammetry. In addition, experimental results were confirmed by obtaining information about the possible spatial structure of the aggregate formed through theoretical calculations based on energy minimization for milrinone- ct-dsDNA and milrinone-human serum albumin mixtures with molecular insertion.

Electrode modification is a technique performed with different chemical and physical methods using various materials, such as polymers, nanomaterials and biological agents in order to enhance sensitivity, selectivity, stability and response of sensors. Modification provides the detection of small amounts of analyte in a complex media with very low limit of detection values. Electrochemical methods are well suited for drug analysis, and they are all-purpose techniques widely used in environmental studies, industrial fields, and pharmaceutical and biomedical analyses. In this review, chemically modified electrodes are discussed in terms of modification techniques and agents, and recent studies related to chemically modified electrodes in electrochemical drug analysis are summarized.

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.

The screen-printed electrodes have gained increasing importance due to their advantages, such as robustness, portability, and easy handling. The manuscript presents the investigation of the interaction between double-strand deoxyribonucleic acid (dsDNA) and three anthracyclines: epirubicin (EPI), idarubicin (IDA), and doxorubicin (DOX) by differential pulse voltammetry on metal nanoparticles modified by screen-printed electrodes. In order to investigate the interaction, the voltammetric signals of dsDNA electroactive bases were used as an indicator. The effect of various metal nanomaterials on the signals of guanine and adenine was evaluated. Moreover, dsDNA/PtNPs/AgNPs/SPE (platinum nanoparticles/silver nanoparticles/screen-printed electrodes) was designed for anthracyclines–dsDNA interaction studies since the layer-by-layer modification strategy of metal nanoparticles increases the surface area. Using the signal of multi-layer calf thymus (ct)-dsDNA, the within-day reproducibility results (RSD%) for guanine and adenine peak currents were found as 0.58% and 0.73%, respectively, and the between-day reproducibility results (RSD%) for guanine and adenine peak currents were found as 1.04% and 1.26%, respectively. The effect of binding time and concentration of three anthracyclines on voltammetric signals of dsDNA bases were also evaluated. The response was examined in the range of 0.3–1.3 ppm EPI, 0.1–1.0 ppm IDA and DOX concentration on dsDNA/PtNPs/AgNPs/SPE. Electrochemical studies proposed that the interaction mechanism between three anthracyclines and dsDNA was an intercalation mode.

Herein, β-cyclodextrin-capped gold nanoparticle surface designed for tyrosinase (Tyr)-based nanosensor is proposed and demonstrated. Integration of the β-cyclodextrin-capped gold nanoparticles on graphite electrode surface was achieved via drop-casting method, Tyr was immobilized on the modified electrode and then used as drug inhibition platform with catechol as the substrate. All optimization studies that affect biosensor response were conducted, and catechol was detected in the linear range of 1.56 μM-25μM catechol concentration with a limit of detection of 0.42 μM and sensitivity of 2.094 μA.μM−1. cm-2. Tyr inhibition was followed with ibuprofen drug active compound with a 15 min incubation time, and the I50 value was found as 213 μM. The sensor is the first in the literature to use an electrochemical method for β-cyclodextrin-capped gold nanoparticles based Tyr biosensor and ibuprofen inhibition. This sensor presents an easy fabrication method, excellent sensor properties, and ibuprofen inhibition capabilities. As a result, it is proposed that the designed sensor is an ideal marker for detecting Tyr inhibition using electrochemical methods and an ibuprofen-based cosmetic cream formulation could be a viable option in the cosmetic market.

Electrochemical methods have been used for the determination of nonsteroidal antiinflammatory drugs (NSAID) just as used in the determination of various drugs. Among voltammetric methods; differential pulse voltammetric method, square wave voltammetric method and linear sweep voltammetric method are the most commonly used ones. NSAIDs are widely used in the treatment of inflammatory conditions such as musculoskeletal disorders (rheumatoid arthritis, osteoarthritis, acute gouty arthritis) and dental pain, menstrual pain, postoperative pain and migraine. In this review, some selected recent electrochemical studies were selected related to the nonsteroidal antiinflammatory drug analyzes. The aim of this review is to evaluate and discuss the advantages, details and usages of electroanalytical methods in the determination of nonsteroidal anti-inflammatory drug.

Introduction: Ultra-Performance Liquid Chromatographic (UPLC) method enables analyst to establish an analysis at higher pressure than High Performance Liquid Chromatographic (HPLC) method towards liquid chromatographic methods. UPLC method provides the opportunity to study a higher pressure compared to HPLC, and therefore smaller column in terms of particle size and internal diameter are generally used in drug analysis. The UPLC method has attracted gradually due to its advantages such as short analysis time, the small amount of waste reagents and the significant savings in the cost of their destruction process. In this review, the recent selected studies related to the UPLC method and its method validation are summarized. The drug analyses and the results of the studies which were investigated by UPLC method, with certain parameters from literature are presented. Background: Quantitative determination of drug active substances by High-Performance Liquid Chromatography (HPLC) from Liquid Chromatography (LC) methods has been carried out since the 1970's with the use of standard analytical LC methods. In today's conditions, rapid and very fast even ultra-fast, flow rates are achieved compared to conventional HPLC due to shortening analysis times, increasing method efficiency and resolution, reducing sample volume (and hence injection volume), reducing waste mobile phase. Using smaller particles, the speed and peak capacity are expanding to new limit and this technology is named as Ultra Performance Liquid Chromatography. In recent years, as a general trend in liquid chromatography, ultra-performance liquid chromatography has taken the place of HPLC methods. The time of analysis was for several minutes, now with a total analysis time of around 1-2 minutes. The benefits of transferring HPLC to UPLC are much better understood when considering the thousands of analyzes performed for each active substance, in order to reduce the cost of analytical laboratories where relevant analysis of drug active substances are performed without lowering the cost of research and development activities. Methods: The German Chemist Friedrich Ferdinand Runge, proposed the use of reactive impregnated filter paper for the identification of dyestuffs in 1855 and at that time the first chromatographic method in which a liquid mobile phase was used, was reviewed. Christian Friedrich Chönbein, who reported that the substances were dragged at different speeds in the filter paper due to capillary effect, was followed by the Russian botanist Mikhail S. Tswet, who planted studies on color pigment in 1906. Tswet observes the color separations of many plant pigments, such as chlorophyll and xanthophyll when he passes the plant pigment extract isolated from plant through the powder CaCO3 that he filled in the glass column. This method based on color separation gives the name of "chromatographie" chromatography by using the words "chroma" meaning "Latin" and "graphein" meaning writing. Results and Conclusion: Because the UPLC method can be run smoothly at higher pressures than the HPLC method, it offers the possibility of analyzing using much smaller column sizes and column diameters. Moreover, UPLC method has advantages, such as short analysis time, the small amount of waste reagents and the significant savings in the cost of their destruction process. The use of the UPLC method especially analyses in biological samples such as human plasma, brain sample, rat plasma, etc. increasingly time-consuming due to the fact that the analysis time is very short compared to the HPLC, because of the small amount of waste analytes and the considerable savings in their cost.

Dihydroergotamine mesylate (DHE), ergotamine derivative, has been offered for clinical use to stop or treat symptoms of an emerging migraine as injection for more than a half century. It is shown that bioavailability of DHE greatly changes between the subjects and up to 99% of the orally absorbed dose may be cleared by first pass metabolism. The aim of this study was to design and optimize DHE fast-dissolving sublingual films for migraine treatment. For this purpose pullulan and maltodextrin was chosen as film-forming polymers and propylene glycol as plasticizer. For optimization process Box Behnken design was used. The formed films were free from air bubbles, cuttings, or cracks. Disintegration, mechanical strength and dissolution of films were compared. It is found that pullulan and maltodextrin formed films with the most desired properties at the concentration of 1.5% and 2%. The application of optimum formulation to rabbits showed that bioavailability of formulation is about 23.35% with a t

In this study, an antiparkinson drug Entacapone (ENP) is electrochemically investigated under optimized conditions using NH2 functionalized multi walled carbon nanotubes (NH2fMWCNT) decorated over glassy carbon electrode (GCE). The surface morphology of the NH2fMWCNT/GCE was probed by scanning electron microscopy (SEM) armed with EDX analysis. Electrochemical impedance spectroscopy (EIS) was employed to investigate the electron transfer capability of modified and bare electrodes. Cyclic voltammetry was used to compare the redox response of ENP on the surface of modified and unmodified electrodes. The influence of interfering agents was also studied to examine the selectivity of the designed sensor. For the purpose of practical applicability of the proposed method, differential pulse voltammetric method was applied for the investigation of ENP in real samples i.e., tablet, human serum and urine. Almost 100% recovery percentages were obtained from tablet, serum and urine samples with RSD% values of less than 2% for all the samples, thus, suggesting promising applicability of the designed electrochemical sensing platform (NH2fMWCNT/GCE) for determination of ENP in pharmaceutical dosage and real samples.

Ascorbic acid (AA), uric acid (UA), and dopamine (DA) are biologically important molecules which have similar structures and important tasks in the human body. Since they usually coexist in biological fluids and oxidize at overlapping potentials; developing a sensitive, selective, simple, fast, and affordable electroanalytical method for simultaneous determination of AA, UA, and DA has always been a prominent research subject. Voltammetry has become one of the most commonly used and important method amongst the other methods due to its high sensitivity and reliability. Moreover, nanomaterials have become very popular in electrochemistry recently with the use of nanosensors in determinations of molecules thanks to unique properties of nanomaterials. This review highlights the most widely used voltammetric methods and nanomaterials in simultaneous electrochemical sensing of AA, UA, and DA; provides an overview of recent studies on simultaneous determination of AA, UA, and DA, and also explains the interference effect of AA, UA, and DA to each other.

Molecularly imprinted polymers (MIPs) mimic the binding sites of antibodies by substituting the amino acid-scaffold of proteins by synthetic polymers. In this work, the first MIP for the recognition of the diagnostically relevant enzyme butyrylcholinesterase (BuChE) is presented. The MIP was prepared using electropolymerization of the functional monomer o-phenylenediamine and was deposited as a thin film on a glassy carbon electrode by oxidative potentiodynamic polymerization. Rebinding and removal of the template were detected by cyclic voltammetry using ferricyanide as a redox marker. Furthermore, the enzymatic activity of BuChE rebound to the MIP was measured via the anodic oxidation of thiocholine, the reaction product of butyrylthiocholine. The response was linear between 50 pM and 2 nM concentrations of BuChE with a detection limit of 14.7 pM. In addition to the high sensitivity for BuChE, the sensor responded towards pseudo-irreversible inhibitors in the lower mM range., Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe; 1138

Molecularly imprinted polymers (MIPs) are biomimetic recognition elements developed for affinity chromatography, sensorics, and potential substitutes of antibodies in therapy. They are prepared by polymerizing one to six monomers in the presence of the target analyte followed by the formation of “paratope-analog” binding sites by the removal of the template from the polymeric scaffold. Electrochemical methods allow for the straightforward synthesis by electropolymerization, template removal by electro-elution, and readout of molecularly imprinted polymers. A wide range of MIP-based electrochemical sensors for low-molecular weight substances, biopolymers as well as cells and viruses have been developed within the past 20 years. All types of nanomaterials have been successfully integrated into the MIP-layer, to enhance the sensitivity. Quantum dots are mostly used in electrochemical sensing to increase the electroactive surface and found limited application as “active” components in (photo) electrochemical MIP-sensors. Integration of quantum dots requires sophisticated preparation procedures, and it is seldom justified by the analytical performance in real samples.

In recent years, we have witnessed an increasing rate of research interest for the polymers that are highly efficient, eco-friendly, and cost-effective materials which also possess multiple physical properties such as conductivity, optical properties, mechanical stability, and surface defect-free films. Quantum dot (QD) and polymer composites exhibit intriguing electronic transitions that resemble single atom behavior because these type of polymers can be coupled with QDs, which are nanocrystals made of semiconductors. QDs are widely used in the fields of analytical chemistry, bioanalysis, and optoelectronics due to their unique, size-tunable electronic, and optical properties. The studies of nanocomposites associated with QDs and polymers, in general, use the QD nanocrystals as the energy donor, and the polymers molecules as acceptors. Electrochemical methods based on QDs/polymers nanocomposites provide significant detection methods that are sensitive, rapid, and low cost. In this chapter, we mainly focus and concentrate on the methods using nanocomposites based on QDs and different types of polymers such as conducting and molecularly imprinted polymers. Using QDs and different types of polymers, electrochemical sensors for different compounds detection and determination of pharmaceuticals, biological samples, and environmental samples are generated. The information about the structures of polymers and examples for the applications of QDs/polymer nanocomposite in the fields of diagnostics and bioanalytics are also summarized in this chapter.

The advantages of quantum dots are a large surface area, low cost, excellent optical and electrochemical properties, and the ability for attractive surface modification. In recent years, quantum dots have become among the most promising materials in biosensor construction. Over the past years, electrochemical enzyme-based biosensors have been considered to develop simple, rapid, and highly sensitive and selective devices for the detection of desired compounds in many different samples. In light of this knowledge, different types of biosensing systems have been developed using quantum dots. In this chapter, enzyme-based electrochemical nanobiosensors using quantum dots are discussed. First, a general description is given of enzymes related with their classification and nomenclature, enzyme kinetics, and inhibition information. Subsequently, generations of enzyme-based biosensors and the methods of immobilization are also described in detail. Additionally, some selected quantum dot-based electrochemical enzyme biosensor studies are summarized and tabulated. Finally, future prospects in this rapidly developing field are also discussed.

Biosensors are very popular systems in several fields including medical, clinical, environment, food-agriculture, security, and forensic sciences. They also require interdisciplinary work that combines biology, analytical chemistry, physics, and bioelectronics. A biosensor is a device that includes a biological recognition element connected or integrated into a transducer. Although different methods are used as transducers, electrochemical techniques are often preferred as good alternative due to their simplicity, low cost, fast response time, and miniaturization. Nanotechnology is used to make more sensitive analysis with electrochemical methods. Many nanomaterials are integrated with electrochemical transducers and one of the most current among these is quantum dots, which are nanometer-sized semiconductor crystals. The final part of the “Electroanalytical Applications of Quantum Dot Based Biosensors” book summarizes the importance of quantum dots for electrochemical biosensors in terms of synthesis, integration into electrochemical techniques, and usage with other materials and also explains the near future expectations for quantum dots.

Quantum dots (QDs) refer to quantum confinement of electrons and hole carriers at dimensions smaller than the Bohr radius. These fluorescent particles have typical dimensions ranging from 1 to 10 nm. There exists redshift in the fluorescence emission peak with respect to the increase in QD size. This chapter encompasses synthetic methods of QDs in terms of hydrolysis, sol-gel, hydrothermal/solvo thermal, exfoliation process, hydrothermal, microwave-hydrothermal synthesis, laser ablation, etc. A number of characterization methods of QDs such as photoluminescence (PL), UV/vis absorption and fluorescence spectroscopy, X-ray photoemission spectroscopy, transmission electron microscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, and dynamic light scattering are also discussed. Moreover, it sheds light on the classification of QDs and their applications.

Environmental pollution control technology has a great demand for detection systems, particularly for pesticides and phenolic compounds. Moreover, analytical systems are highly required for the dual detection of different pollutants using the same platform. In that direction, a new, reliable, easy to use and disposable biosensor for the detection of catechol and chlorpyrifos is proposed. The designed biosensor with synergic properties between the high conductivity of iridium oxide nanoparticles, low-cost screen printed electrodes and the efficiency of tyrosinase shows broad linearity ranges for catechol and chlorpyrifos detection. Using this biosensor, very low limits of detection for catechol (0.08 μM) and chlorpyrifos (0.003 μM) are observed and recoveries of spiked tap and river water samples have also been studied showing very good recoveries., This work was supported by a grant from MICINN through MAT2011-25870 project. S. Kurbanoglu acknowledges Ankara University’s BEYOD program.

Today, biotechnological process applications are frequently used by an increasing importance in terms of industry and research. One of the natural consequences of scientific advances is the provision of more rapid progression by the effects on several scientific fields. Therefore, the rapid introduction of biotechnological processes into our daily lives leads to the development of new experimental tools (imaging methods and metabolic engineering), universal methods of analysis (genomics, proteomics, and metabolomics), and bioinformatics, which are able to respond rapidly to the needs and become more responsive. In this chapter, it is tried to define the bioprocess monitoring and analytical methods for bioprocesses with their measurement principles. Moreover, biologically varying sensors that are used in biomass monitoring and biomass concentration analysis are also defined. Turbidity sensors and impedance sensors, cell morphology analysis, in situ microscope systems, metabolic activity analysis, etc., are also stated. Current challenges with some novel examples are also shared.