Disposable Screen-printed Electrodes Research Articles

Determination of total and electrolabile copper in agricultural soil by using disposable modified-carbon screen-printed electrodes

The objective of the study is to evaluate modified-carbon screen-printed working electrodes (SPE) combined with square wave anodic stripping voltammetry (SWASV) to determine electrolabile and total copper in soils with the perspective to assess the environmental hazard resulting from copper anthropogenic contamination. The voltammetric method was investigated using a mineralized certified reference soil such that it can be assumed that the copper was totally under electrolabile form in the solution of mineralized soil. In optimal conditions, a copper recovery of 97% and a relative standard deviation (RSD) of 9% were found. The limits of detection and quantification for copper were 0.4 and 1.3 μg L(-1), respectively. Finally, the method was applied on soil leachates, which allowed evaluating the cupric transfer from the soil to the leachates and quantifying the electrolabile copper part in leachates.

Fast and Sensitive Detection of Pb2+ in Foods Using Disposable Screen-Printed Electrode Modified by Reduced Graphene Oxide

In this study, reduced graphene oxide (rGO) was electrochemically deposited on the surface of screen-printed carbon electrodes (SPCE) to prepare a disposable sensor for fast detection of Pb2+ in foods. The SEM images showed that the rGO was homogeneously deposited onto the electrode surface with a wrinkled nanostructure, which provided 2D bridges for electron transport and a larger active area for Pb2+ adsorption. Results showed that rGO modification enhanced the activity of the electrode surface, and significantly improved the electrochemical properties of SPCE. The rGO modified SPCE (rGO-SPCE) was applied to detect Pb2+ in standard aqueous solution, showing a sharp stripping peak and a relatively constant peak potential in square wave anodic stripping voltammetry (SWASV). The linear range for Pb2+ detection was 5∼200 ppb (R2 = 0.9923) with a low detection limit of 1 ppb (S/N = 3). The interference of Cd2+ and Cu2+ at low concentrations was effectively avoided. Finally, the rGO-SPCE was used for determination of lead in real tap water, juice, preserved eggs and tea samples. Compared with results from graphite furnace atomic absorption spectroscopy (GFAAS), the results based on rGO-SPCE were both accurate and reliable, suggesting that the disposable sensor has great potential in application for fast, sensitive and low-cost detection of Pb2+ in foods.

Ultrasensitive amperometric magnetoimmunosensor for human C-reactive protein quantification in serum

A highly sensitive magnetoimmunosensor for the determination of human C-reactive protein (CRP) is described in this work. A sandwich format involving covalent immobilization of the capture antibody (antiCRP) onto carboxylic-modified magnetic beads (HOOC-MBs) activated with N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS), the antigen–antibody reaction and incubation of the modified MBs with a biotynilated antibody (biotin-antiCRP), is used. Furthermore, an incubation step with a Streptavidin HRP (Strp-HRP) conjugate is employed to allow monitoring of the affinity reaction. The resulting modified MBs are captured by a magnet placed under the surface of a disposable gold screen-printed electrode (Au/SPE) and the amperometric responses are measured at −0.10V (vs. a Ag pseudo-reference electrode), upon addition of 3,3′,5,5′-tetramethylbenzidine (TMB) as electron transfer mediator and H2O2 as the enzyme substrate. The CRP magnetoimmunosensor exhibited a wide range of linearity between 0.07 and 1000ngmL−1 with a low detection limit of (0.021±0.005)ngmL−1. The magnetoimmunosensor was successfully applied to the analysis of an international standard for CRP serum.

Disposable amperometric magnetoimmunosensor for the sensitive detection of the cardiac biomarker amino-terminal pro-B-type natriuretic peptide in human serum

A novel amperometric magnetoimmunosensor using an indirect competitive format is developed for the sensitive detection of the amino-terminal pro-B-type natriuretic peptide (NT-proBNP). The immunosensor design involves the covalent immobilization of the antigen onto carboxylic-modified magnetic beads (HOOC-MBs) activated with N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS), and further incubation in a mixture solution containing variable concentrations of the antigen and a fixed concentration of an HRP-labeled detection antibody. Accordingly, the target NT-proBNP in the sample and that immobilized on the MBs compete for binding to a fixed amount of the specific HRP-labeled secondary antibody. The immunoconjugate-bearing MBs are captured by a magnet placed under the surface of a disposable gold screen-printed electrode (Au/SPE). The amperometric responses measured at –0.10V (vs. a Ag pseudo-reference electrode), upon addition of 3,3′,5,5′-tetramethylbenzidine (TMB) as electron transfer mediator and H2O2 as the enzyme substrate, are used to monitor the affinity reaction. The developed magnetoimmunosensor provides attractive analytical characteristics in 10-times diluted human serum samples, exhibiting a linear range of clinical usefulness (0.12–42.9ngmL−1) and a detection limit of 0.02ngmL−1, which can be used in clinical diagnosis of chronic heart failure in the elderly and for classifying patients at risk of death after heart transplantation. The magnetoimmunosensor was successfully applied to the analysis of spiked human serum samples.

Voltammetric determination of trace Tl(I) at disposable screen-printed electrodes modified with bismuth precursor compounds

This work reports the trace determination of Tl(I) by anodic stripping voltammetry (ASV) on novel screen-printed electrodes bulk-modified with bismuth precursor compounds (bismuth oxide, bismuth aluminate and bismuth zirconate). A bismuth-film was formed at the electrode surface as the precursor was reduced to metallic bismuth during the electrolytic preconcentration step. The effect of the fabrication parameters (the type of the bismuth precursor compound and the precursor content in the carbon ink), the instrumental variables (stripping waveform, deposition time and deposition potential) and chemical conditions (supporting electrolyte) were studied in detail. The limits of detection for Tl(I) were in the range 0.9–1.1μgL−1 while the reproducibility on the same sensor (expressed as the % relative standard deviation (n=8)), was in the range 6.0–7.2% at the 20μgL−1 level. The sensors were applied to the determination of Tl(I) in a certified lake water sample. The modified electrodes possess analytical characteristics comparable to electroplated bismuth-film electrodes (BiFEs) and offer a wide scope as mercury-free disposable sensors for screening of trace metals.

New Screen Printed Electrode Based on Graphite and Polyurethane Composite for the Determination of Acetaminophen

A disposable screen-printed electrode based on a graphite and polyurethane resin composite (EIGPU) was developed and evaluated as a voltammetric detector in pharmaceutical analysis. Using cyclic voltammetry, an analytical curve was obtained with the linear dynamic range between 1.00–100 µmol L−1 and a detection limit of 8.18 × 10−7 mol L−1 for acetaminophen (paracetamol) as a probe. During the APAP determination in pharmaceutical formulations, recoveries between 97.2 and 102% were found. There were no interferences from ascorbic acid and other constituents of the pharmaceutical formulation at the 95% confidence level compared to HPLC analysis.

Amperometric Hydrogen Peroxide Biosensor Based on Horseradish Peroxidase Entrapped in Titania Sol-Gel Film on Screen-Printed Electrode

We report the fabrication of disposable and flexible Screen-Printed Electrodes (SPEs). This new type of screen-printed electrochemical platform consists of Ag nanoparticles (AgNPs) and graphite composite. For this purpose, silver nanoparticles were first synthesized by a chemical reduction method. The morphology and structure of the AgNPs were analyzed using a Scanning Electron Microscope (SEM) and UV-Visible spectroscopy. Graphite was chosen as the working electrode material for the fabrication of a thick-film. The fabrication of a screen-printed hydrogen peroxide biosensor consisting of three electrodes on a polyethylene terephthalate (PET) substrate was performed with a spraying approach (working, counter and reference: enzyme electrode, graphite, pseudo reference: Ag/AgCl). This biosensor was fabricated by immobilizing the peroxidase enzyme (HRP) in a Titania sol-gel membrane which was obtained through a vapor deposition method. The biosensor had electrocatalytic activity in the reduction of H2O2 with linear dependence on H2O2 concentration in the range of 10－5 to 10－3 M; the detection limit was 4.5 × 10－6 M.

Rapid and sensitive in-situ detection of polar antibiotics in water using a disposable Ag–graphene sensor based on electrophoretic preconcentration and surface-enhanced Raman spectroscopy

A disposable Ag–graphene sensor was developed for rapid and sensitive in-situ detection of polar antibiotics in water using electrophoretic preconcentration (EP) and surface-enhanced Raman spectroscopy (SERS). The Ag–graphene sensor was fabricated by depositing Ag–graphene nanocomposites synthesized through a facile one-pot method on the disposable screen-printed electrodes (SPEs) and characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). SERS properties and detection applicability of the developed sensor were systematically investigated. It is shown that the polar antibiotics can be selectively adsorbed on the oppositely charged sensors after applying different potentials during the EP procedure, and the SERS signals of antibiotics with an effective amplification can be achieved with proper time of preconcentration. Moreover, the Ag–graphene sensor could facilitate the molecule adsorption through weak π–π interactions between graphene and antibiotics, further improving the sensitivity of SERS detection. Under the optimum EP conditions, the representative SERS spectra of a mixed solution containing four different antibiotics can be obtained within 10min, and each antibiotic is easily distinguished by its characteristic peaks with a sub-nM detection level. The results demonstrate that the proposed disposable Ag–graphene sensor based on EP–SERS can be used for rapid and sensitive in-situ detection of polar antibiotics in aqueous samples without a pre-separation step.

Preparation, characterization of Fe3O4 at TiO2 magnetic nanoparticles and their application for immunoassay of biomarker of exposure to organophosphorus pesticides

Novel Fe3O4 at TiO2 magnetic nanoparticles were prepared and developed for a new nanoparticle-based immunosensor for electrochemical quantification of organophosphorylated butyrylcholinesterase (BChE) in plasma, a specific biomarker of exposure to organophosphorus (OP) agents. The Fe3O4 at TiO2 nanoparticles were synthesized by hydrolysis of tetrabutyltitanate on the surface of Fe3O4 magnetic nanospheres, and characterized by attenuated total reflection Fourier-transform infrared spectra, transmission electron microscope and X-ray diffraction. The functional Fe3O4 at TiO2 nanoparticles were performed as capture antibody to selectively enrich phosphorylated moiety instead of phosphoserine antibody in the traditional sandwich immunoassays. The secondary recognition was performed by quantum dots (QDs)-tagged anti-BChE antibody (QDs-anti-BChE). With the help of a magnet, the resulting sandwich-like complex, Fe3O4 at TiO2/OP-BChE/QDs-anti-BChE, was easily isolated from sample solutions and the released cadmium ions were detected on a disposable screen-printed electrode (SPE). The binding affinities were investigated by both surface plasmon resonance (SPR) and square wave voltammetry (SWV). This method not only avoids the drawback of unavailability of commercial OP-specific antibody but also amplifies detection signal by QDs-tags together with easy separation of samples by magnetic forces. The proposed immunosensor yields a linear response over a broad OP-BChE concentrations range from 0.02 to 10nM, with detection limit of 0.01nM. Moreover, the disposable nanoparticle-based immunosensor has been validated with human plasma samples. It offers a new method for rapid, sensitive, selective and inexpensive screening/evaluating exposure to OP pesticides and nerve agents.

Electrochemical Determination of Methotrexate at a Disposable Screen-Printed Electrode and Its Application Studies

Methotrexate is widely used for treatment of various neoplastic diseases. The present work details the voltammetric analysis of Methotrexate at a multi-walled carbon nanotube (MWNT) modified screen-printed electrode (SPE). The fabrication and evaluation of MWNT-derived screen-printed electrochemical sensors based on a MWNT ink are reported. The fabricated MWNT strips combine the attractive advantages of CNT materials and disposable screen printed electrodes. The anodic voltammetric behavior of methotrexate was studied using cyclic and square-wave voltammetric techniques in tris-HCl (pH = 7.5) solution. The oxidation of methotrexate was an irreversible adsorptive-driven process. The experimental conditions such as carbon ink, MWNT, pH, the concentration, and nature of buffer were investigated to optimize the determination of methotrexate. Under optimum conditions, the square-wave voltammetric peak currents were in a linear relationship to methotrexate concentrations in the range of 5.0 × 10−7M–1.0 × 10−4 M with a detection limit of 1.0 × 10−7 M. The MWNT/SPE showed good stability, selectivity, and was successfully used to quantify methotrexate in pharmaceutical formulations.

Voltammetric determination of Rutin at Screen-Printed carbon disposable electrodes

Abstract Rutin is a flavonoid commonly employed for many therapeutic purposes. Although the electroactive phenolic groups of rutin might be oxidized at low applied potential, the adsorption of oxidized species changes the electrode surface. As a consequence, the repeatability and reproducibility of the method decreases, which limits electroanalytical applications. This paper describes the use of disposable screen-printed electrodes as an alternative to improve the electrochemical quantification of rutin in commercial and standard samples. The electrochemical behavior was consistent to what is observed using other carbon electrodes: an adsorption-involved step and a pH-dependent oxidation process. The replacement of the electrodes between the analyses ensured rapid analysis, good intermediate precision and repeatability. The proposed method was successfully applied to rutin determination in pharmaceutical samples of capsules, with the limit of quantification being 0.30 µM.

Part two: Analytical optimisation of a procedure for lead detection in milk by means of bismuth-modified screen-printed electrodes

This work reports the optimisation of a new analytical method for lead ion detection in milk; the electrochemical detection scheme is based on the method that was described in Part I [1]. It features the use of a disposable, environmentally friendly bismuth film electrode to replace the traditionally used (toxic) mercury one while here we report an arduous development of sample treatment so that the simple device can be applied as a screening tool in many settings. For this purpose, a milk pre-treatment procedure by means of wet digestion with HCl, HClO4, and H2O2 combined with an ultrasonic treatment was developed. The detection of lead ions in treated milk was then carried out using a disposable screen-printed electrode modified with Nafion® and an “in situ” bismuth film, with the analysis being performed in anodic stripping voltammetry mode. The analytical method developed allows the detection of milk contaminated with lead ions at a concentration of 20μgKg−1 (legal limit) and it can be proposed as a screening method for routine analysis of lead ions in milk with the advantage of employing inexpensive and portable instrumentation. Moreover, dedicated software supported by a portable instrument introduces procedures that are essential to avoid distortion from ambient lead contamination and also makes it possible for an unskilled operator to carry out each step of the analysis.

Novel Screen-Printed Gold Nano Film Electrode for Trace Mercury(II) Determination Using Anodic Stripping Voltammetry

Integrating the screen printing technique with the vacuum evaporation method, we developed a novel and disposable screen-printed gold film electrode (SPGFE) in the present work. First, a conductive silver layer, a connection graphite-carbon layer, and an insulating polymer layer were successively printed onto a flexible polyethylene terephthalate (PET) substrate. Then, a gold thin film was achieved on the scheduled vacant site by use of the vacuum evaporation method. In order to enhance the electroanalytical performance of the SPGFE, the thickness of the gold film was controlled in the range of 70–80 nm under optimum conditions. The fabricated SPGFE was applied to detect trace mercury(II) based on the square-wave anodic stripping voltammetry (SWASV). The results indicated that the proposed SPGFE exhibited higher sensitivity to trace mercury(II) than the gold disc electrode. The stripping current was linearly related to the concentration of mercury(II) in the range of 16–280 µg/L (R2 = 0.9919) and 1.2–8.0 µg/L (R2 = 0.9977), with a detection limit of 0.8 µg/L (S/N = 3) under 180 s accumulation. The SPGFE was further used to detect mercury in real samples, and the obtained results revealed a good agreement with those of inductively coupled plasma atomic emission spectrometry (ICP-AES) and atomic absorption spectroscopy (AAS). The highly sensitive and environmental friendly electrode, as another type of “mercury-free” electrode, holds great promise in stripping measurements.

Portable reconfigurable instrument for analytical determinations using disposable electrochemiluminescent screen-printed electrodes

A portable reconfigurable instrument platform for electrochemiluminescence (ECL)-based disposable screen-printed electrodes is described. The reader unit consists of a potentiostat and a photodiode as a light-to-current converter integrated in the same instrument. For powerful and versatile analog conditioning, a very recent electronic solution has been included: a Field Programmable Analog Array (FPAA) capable of reconfiguring filter and gain stages in real time. To check the instrument's performance as a sensor platform, two luminophores (tris(2,2′bipyridyl)ruthenium(II) and luminol) and two representative correactants widely used, triethylamine and cholesterol, were selected. The calibration functions obtained show a linear dependence with dynamic ranges from 0.05 to 10.0mgl−1 for triethylamine, and 2.0·10−5–1.4·10−4M for cholesterol, with detection limits of 0.2mgl−1 and 1.1·10−5M, respectively, and a sensor-to-sensor reproducibility (relative standard deviation, RSD) of around 3.2% and 3.3% respectively at the medium-range level. This instrument offers a new advance in the portability of electrochemiluminescent determinations.

Gold nanoparticles modified ceria nanoparticles for the oxidation of hydrazine with disposable screen-printed electrode

Gold nanoparticles (AuNPs) modified cerium oxide (CeO2 or ceria) nanoparticles (AuNP–CeO2) were prepared with the direct deposition of AuNPs onto CeO2 surface. It was found the prepared nanoparticles have excellent electrocatalytic activity towards hydrazine oxidation. The catalytic activity of AuNP–CeO2 is much higher than CeO2, indicating possible synergistic effect between AuNPs and CeO2. The AuNP–CeO2 modified screen-printed electrode can be used as disposable electrochemical devices for hydrazine detection and the AuNP–CeO2 nanoparticles can also be used as electrode material for hydrazine fuel cell.

Application of Disposable Screen-printed Electrode as an Epirubicin Sensor and Relation among Whole Blood and Tissue Concentrations of Epirubicin

Application of Disposable Screen-printed Electrode as an Epirubicin Sensor and Relation among Whole Blood and Tissue Concentrations of Epirubicin

Simultaneous determination of ascorbic acid, dopamine and uric acid using high-performance screen-printed graphene electrode

A disposable and sensitive screen-printed electrode using an ink containing graphene was developed. This electrode combined the advantages of graphene and the disposable characteristic of electrode, which possessed wide potential window, low background current and fast electron transfer kinetics. Compared with the electrodes made from other inks, screen-printed graphene electrode (SPGNE) showed excellent electrocatalytic activity for the oxidation of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Three well-defined sharp and fully resolved anodic peaks were found at the developed electrode. Differential pulse voltammetry was used to simultaneous determination of AA, DA, and UA in their ternary mixture. In the co-existence system of these three species, the linear response ranges for the determination of AA, DA, and UA were 4.0–4500μM, 0.5–2000μM, and 0.8–2500μM, respectively. The detection limits (S/N=3) were found to be 0.95μM, 0.12μM, and 0.20μM for the determination of AA, DA, and UA, respectively. Furthermore, the SPGNE displayed high reproducibility and stability for these species determination. The feasibility of the developed electrode for real sample analysis was investigated. Results showed that the SPGNE could be used as a sensitive and selective sensor for simultaneous determination of AA, DA, and UA in biological samples, which may provide a promising alternative in routine sensing applications.

Magnetic particle-based immunoassay of phosphorylated p53 using protein cage templated lead phosphate and carbon nanospheres for signal amplification

Phosphorylated p53 at serine 15 (phospho-p5315) is a potential biomarker of gamma-radiation exposure. In this paper, we described a new magnetic particle (MP)-based electrochemical immunoassay of human phospho-p5315 using carbon nanospheres (NS) and protein cage nanoparticles (PCN) for signal amplification. Greatly enhanced sensitivity was achieved for three reasons: 1) PCN and the p5315 signal antibody (p5315 Ab2) are linked to the carbon NS (PCN-p5315 Ab2-NS) as a label; 2) PCN increases the amount of metal ions in the cavity of each apoferritin; 3) MPs capture a large amount of primary antibodies. Protein cage templated metallic phosphates, instead of enzymes, as multi-labels have the advantage of eliminating the addition of mediator or immunoreagents and, thus, makes the immunoassay system simpler. Subsequent stripping voltametric analysis, detected olead ions on a disposable screen-printed electrode. The response current was proportional to the phospho-p5315 concentration in the range of 0.02 to 20 ng mL−1 with a detection limit of 0.01 ng mL−1, which was 30-fold lower than that of the ELISA measurement of phospho-p5315. This method shows an acceptable stability and reproducibility and the assay results for phospho-p5315-spiked human serum presented good recovery rates.

Impedimetric thrombin aptasensor based on chemically modified graphenes

Highly sensitive biosensors are of high importance to the biomedical field. Graphene represents a promising transducing platform for construction of biosensors. Here for the first time we compare the biosensing performance of a wide set of graphenes prepared by different methods. In this work, we present a simple and label-free electrochemical impedimetric aptasensor for thrombin based on chemically modified graphene (CMG) platforms such as graphite oxide (GPO), graphene oxide (GO), thermally reduced graphene oxide (TR-GO) and electrochemically reduced graphene oxide (ER-GO). Disposable screen-printed electrodes were first modified with chemically modified graphene (CMG) materials and used to immobilize a DNA aptamer which is specific to thrombin. The basis of detection relies on the changes in impedance spectra of redox probe after the binding of thrombin to the aptamer. It was discovered that graphene oxide (GO) is the most suitable material to be used as compared to the other three CMG materials. Furthermore, the optimum concentration of aptamer to be immobilized onto the modified electrode surface was determined to be 10 μM and the linear detection range of thrombin was 10-50 nM. Lastly, the aptasensor was found to demonstrate selectivity for thrombin. Such simply fabricated graphene oxide aptasensor shows high promise for clinical diagnosis of biomarkers and point-of-care analysis.

Electrochemistry of Escherichia coli JM109: Direct electron transfer and antibiotic resistance

In this study, the cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were used to investigate the extracellular electron transfer from Escherichia coli JM109. It was demonstrated that the formal redox potential of direct electron transfer between electrode and an E. coli JM109 cell in aerobic buffer corresponds to −0.42 V vs. Ag/AgCl. Based on the electroactivity of bacterial cells, the electrochemical system for definition of sensitivity of microbiological material to antibiotics cefepime, ampicillin, amikacin, and erythromycin was proposed. The results obtained indicate that with electrochemical methods it is possible to provide screening of potential drugs for bacterial diseases. The electrochemical method allows estimating the degree of E. coli JM109 cells resistance to antibiotics within 2–5 h using disposable screen-printed graphite electrodes.