Search

A nanocomposite consisting of platinum particles, polyaniline and Ti3C2 MXene (Pt/PANI/MXene) was used to modify a screen-printed carbon electrode (SPCE) to obtain sensors for hydrogen peroxide and lactate. This nanocomposite was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) to determine the physical morphologies and the nanocomposite elements. The modified electrode exhibited the improved current response towards hydrogen peroxide (H2O2) compared with an unmodified electrode and provided a low detection limit of 1.0 μM. When lactate oxidase was immobilized on the modified electrode, the electrode responded to lactate via the H2O2 generated in the enzymatic reaction. The lactate assay was performed by amperometry at a constant potential of +0.3 V (vs. Ag/AgCl). The linear range was found to be from 0.005 to 5.0 mM with a detection limit of 5.0 μM for lactate. Ultimately, this biosensor was used for the determination of lactate in milk samples with high stability and reliability. [ABSTRACT FROM AUTHOR]

A paper-based analytical device (PAD) with an integrated composite electrode for non-enzymatic creatinine sensing was developed. The electrode was produced and optimization was efficiently accomplished using a rapid digital dispensing approach. The electrochemical sensor was fabricated using an HP D300 digital dispenser to deliver a copper oxide and ionic liquid composite onto an electrochemically reduced graphene modified screen-printed carbon electrode (CuO/IL/ERGO/SPCE) on a PAD. The modified electrode was characterized using electrochemical and microscopic techniques. Electrochemical detection of creatinine was performed on the SPCE using amperometry at a constant potential. Under optimized conditions, the paper-based sensor exhibited a linear range of 0.01–2.0 mM (R2 = 0.99) and the limit of detection was 0.22 μM (S/N = 3, IUPAC definition) for creatinine. The simple fabrication process, low cost, and clinically appropriate creatinine sensitivity make this device applicable for point-of-care use. Image 1 • A CuO/IL/ERGO modified paper-based screen printed electrode was constructed and used as a non-enzymatic creatinine sensor. • An HP D300 dispenser was used to enable efficient electrode modification, leading to improved sensitivity and reproducibility. • The sensitivity was sufficient for detecting clinically relevant creatinine levels in acute kidney injury diagnosis. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Label-free paper-based electrochemical immunosensor based on polyaniline/graphene is prepared for human IFN-γ detection. • High conductivity and large surface area of polyaniline/graphene significantly enhances immunosensor sensitivity. • This sensor is sensitive, selective, inexpensive, disposable and portable for rapid detection of human IFN-γ. • This approach might be an alternative tool for human IFN-γ screening in medical diagnosis. Abstract Human interferon-gamma (IFN-γ) plays an important role in diagnosis of tuberculosis susceptibility, which is one of the crucial health problems worldwide. Here, a novel platform of paper-based microfluidic device coupled with label-free electrochemical impedance immunosensor was developed for sensitive detection of human IFN-γ. Polyaniline (PANI) was deposited on a graphene (G) screen-printed paper electrode by using cyclic voltammetry. The modified electrode provides high electrochemical conductivity and surface area for antibody immobilization, which significantly enhances the sensitivity. A linear relationship between impedance and logarithmic concentrations of human IFN-γ was found in a range of 5―1000 pg mL―1 with a detection limit (LOD) of 3.4 pg mL―1. Interestingly, the PANI-G modified electrodes display 31-fold higher sensitivity compared to PANI-modified electrodes. The PANI-G modified electrode was successfully applied to the determination of human IFN-γ in human serum with a good reproducibility. Moreover, the system offers several advantages including low cost, low sample volume requirement, disposability, and rapid analysis relative to traditional methods, allowing the platform to be used as an alternative tool for human IFN-γ screening. [ABSTRACT FROM AUTHOR]

A fully inkjet-printed disposable and low cost paper-based device for potentiometric Na+- or K+-ion sensing has been developed. A printed ionophore-based all-solid-state ion selective electrode on a graphene/poly(3,4-ethylenediox-ythiophene) polystyrenesulfonate (G/PEDOT:PSS) nanocomposite solid contact and a printed all-solid state reference electrode consisting of a pseudosilver/silver chloride electrode coated by a lipophilic salt-incorporating poly(vinyl chloride) membrane overprinted with potassium chloride have been combined on a microfluidically patterned paper substrate. Devices are built on standard filter paper using off-the-shelf materials. Ion sensing has been achieved within 180 s by simple addition of 20 μL of sample solution without electrode preconditioning. The limits of detection were 32 and 101 μM for Na+ and K+, respectively. The individual single-use sensing devices showed near Nernstian response of 62.5 ± 2.1 mV/decade (Na+) and 62.9 ± 1.1 mV/decade (K+) with excellent standard potential (E0 ) reproducibilities of 455.7 ± 5.1 mV (Na+) and 433.9 ± 2.8 mV (K+). The current work demonstrates the promising possibility of obtaining low-cost and disposable paper-based potentiometric sensing devices potentially manufacturable at large scales with industrial inkjet printing technology. [ABSTRACT FROM AUTHOR]

This work describes the development of an electrochemical sensor for simultaneous detection of Zn(II), Cd(II), and Pb(II) using a graphene–polyaniline (G/PANI) nanocomposite electrode prepared by reverse-phase polymerization in the presence of polyvinylpyrrolidone (PVP). Two substrate materials (plastic film and filter paper) and two nanocomposite deposition methods (drop-casting and electrospraying) were investigated. Square-wave anodic stripping voltammetry currents were higher for plastic vs. paper substrates. Performance of the G/PANI nanocomposites was characterized by scanning electron microscopy (SEM) and cyclic voltammetry. The G/PANI-modified electrode exhibited high electrochemical conductivity, producing a three-fold increase in anodic peak current (vs. the unmodified electrode). The G/PANI-modified electrode also showed evidence of increased surface area under SEM. Square-wave anodic stripping voltammetry was used to measure Zn(II), Cd(II), and Pb(II) in the presence of Bi(III). A linear working range of 1–300 μg L −1 was established between anodic current and metal ion concentration with detection limits (S/N = 3) of 1.0 μg L −1 for Zn(II), and 0.1 μg L −1 for both Cd(II) and Pb(II). The G/PANI-modified electrode allowed selective determination of the target metals in the presence of common metal interferences including Mn(II), Cu(II), Fe(III), Fe(II), Co(III), and Ni(II). Repeat assays on the same device demonstrated good reproducibility (%RSD < 11) over 10 serial runs. Finally, this system was utilized for determining Zn(II), Cd(II), and Pb(II) in human serum using the standard addition method. [ABSTRACT FROM AUTHOR]

Abstract: A novel nanocomposite of graphene (G), polyvinylpyrrolidone (PVP) and polyaniline (PANI) has been successfully prepared and used for the modification of paper-based biosensors via electrospraying. The droplet-like nanostructures of G/PVP/PANI-modified electrodes are obtained with an average size of 160±1.02nm. Interestingly, the presence of small amount of PVP (2mgmL−1) in the nanocomposites can substantially improve the dispersibility of G and increase the electrochemical conductivity of electrodes, leading to enhanced sensitivity of the biosensor. The well-defined cyclic voltammogram of standard ferri/ferrocyanide is achieved on a G/PVP/PANI-modified electrode with a 3-fold increase in the current signal compared to an unmodified electrode. This modified electrode also exhibits excellent electrocatalytic activity towards the oxidation of hydrogen peroxide (H2O2). Furthermore, cholesterol oxidase (ChOx) is attached to G/PVP/PANI-modified electrode for the amperometric determination of cholesterol. Under optimum conditions, a linear range of 50μM to 10mM is achieved and the limit of detection is found to be 1 μM for cholesterol. Finally, the proposed system can be applied for the determination of cholesterol in a complex biological fluid (i.e. human serum). [Copyright &y& Elsevier]

Highlights: [•] A novel electrode based on electrospun graphene/polyaniline/polystyrene nanofibers has been developed. [•] The proposed system provides ultrahigh sensitivity, good selectivity and wide linearity for the determination of dopamine. [•] This system was successfully applied to determine dopamine in complex biological environment with excellent reproducibility. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the rapid detection of cholesterol using poly(dimethylsiloxane) microchip capillary electrophoresis, based on the coupling of enzymatic assays and electrochemical detection, was developed. Direct amperometric detection for poly(dimethylsiloxane) (PDMS) microchip capillary electrophoresis was successfully applied to quantify cholesterol levels. Factors influencing the performance of the method (such as the concentration and pH value of buffer electrolyte, concentration of cholesterol oxidase enzyme (ChOx), effect of solvent on the cholesterol solubility, and interferences) were carefully investigated and optimized. The migration time of hydrogen peroxide, product of the reaction, was less than 100s when using 40mM phosphate buffer at pH 7.0 as the running buffer, a concentration of 0.68U/mL of the ChOx, a separation voltage of +1.6kV, an injection time of 20s, and a detection potential of +0.5V. PDMS microchip capillary electrophoresis showed linearity between 38.7μg/dL (1μM) and 270.6mg/dL (7mM) for the cholesterol standard; the detection limit was determined as 38.7ng/dL (1nM). To demonstrate the potential of this assay, the proposed method was applied to quantify cholesterol in bovine serum. The percentages of recoveries were assessed over the range of 98.9–101.8%. The sample throughput was found to be 60 samples per hour. Therefore, PDMS microchip capillary electrophoresis, based on the coupling of enzymatic assays and electrochemical detection, is very rapid, accurate and sensitive method for the determination of cholesterol levels. [Copyright &y& Elsevier]

A significant bottleneck exists for mass-production of ion-selective electrodes despite recent developments in manufacturing technologies. Here, we present a fully-automated system for large-scale production of ISEs. Three materials, including polyvinyl chloride, polyethylene terephthalate and polyimide, were used as substrates for fabricating ion-selective electrodes (ISEs) using stencil printing, screen-printing and laser engraving, respectively. We compared sensitivities of the ISEs to determine the best material for the fabrication process of the ISEs. The electrode surfaces were modified with various carbon nanomaterials including multi-walled carbon nanotubes, graphene, carbon black, and their mixed suspensions as the intermediate layer to enhance sensitivities of the electrodes. An automated 3D-printed robot was used for the drop-cast procedure during ISE fabrication to eliminate manual steps. The sensor array was optimized, and the detection limits were 10–5 M, 10–5 M and 10–4 M for detection of K+, Na+ and Ca2+ ions, respectively. The sensor array integrated with a portable wireless potentiometer was used to detect K+, Na+ and Ca2+ in real urine and simulated sweat samples and results obtained were in agreement with ICP-OES with good recoveries. The developed sensing platform offers low-cost detection of electrolytes for point-of-care applications. [ABSTRACT FROM AUTHOR]

We report herein the first development of graphene-polyaniline modified carbon paste electrode (G-PANI/CPE) coupled with droplet-based microfluidic sensor for high-throughput detection of 4-aminophenol (4-AP) in pharmaceutical paracetamol (PA) formulations. A simple T-junction microfluidic platform using an oil flow rate of 1.8 μL/min and an aqueous flow rate of 0.8 μL/min was used to produce aqueous testing microdroplets continuously. The microchannel was designed to extend the aqueous droplet to cover all 3 electrodes, allowing for electrochemical measurements in a single droplet. Parameters including flow rate, water fraction, and applied detection potential (E det ) were investigated to obtain optimal conditions. Using G-PANI/CPE significantly increased the current response for both cyclic voltammetric detections of ferri/ferrocyanide [Fe(CN) 6 ] 3−/4− (10 times) and 4-AP (2 times), compared to an unmodified electrode. Using the optimized conditions in the droplet system, 4-AP in the presence of PA was selectively determined. The linear range of 4-AP was 50–500 μM (R 2 = 0.99), limit of detection (LOD, S/N = 3) was 15.68 μM, and limit of quantification (LOQ, S/N = 10) was 52.28 μM. Finally, the system was used to determine 4-AP spiked in commercial PA liquid samples and the amounts of 4-AP were found in good agreement with those obtained from the conventional capillary zone electrophoresis/UV–Visible spectrophotometry (CZE/UV–Vis). The proposed microfluidic device could be employed for a high-throughput screening (at least 60 samples h −1 ) of pharmaceutical purity requiring low sample and reagent consumption. [ABSTRACT FROM AUTHOR]

This work introduces a low-cost adhesive tape combined with a hydroxylamine/polyvinyl alcohol/polyethylene oxide (HA/PVA/PEO) blend film to fabricate novel devices for improving sensitivity of gold nanoparticle (AuNP)-based lateral flow immunoassays (LFIAs) via two platforms: (1) LFIA device with integrated gold enhancement and (2) LFIA device with two independent sample inlets. The detection of ferritin has been used for proof-of-concept. The adhesive tape inserted in the devices assists to separate two solutions independently flowing from two different inlets toward a nitrocellulose membrane. On-device gold enhancement was achieved by the enlargement of AuNPs via the catalytic reaction of KAuCl4 and HA using the HA/PVA/PEO blend film easily prepared via a solution-casting technique, which could delay the flow of HA released from the film for 180s and improve storage stability of the device. Under optimal conditions evaluated by naked eyes, the gold enhancement (LOD = 0.5 ng/mL) and double-sample inlet (LOD = 2 ng/mL) devices exhibited 20-fold and fivefold higher sensitivity respectively than a conventional device, verifying the sensitivity improvement. Furthermore, the proposed device was successfully detected ferritin in human serum samples within 10 min via naked-eye observation, exhibiting rapidity and simplicity of use, and the capability to perform on-site assays. [ABSTRACT FROM AUTHOR]

An ultra-performance liquid chromatography (UPLC) coupled with graphene/polyaniline (G/PANI)-modified screen-printed carbon electrode was developed for separation and sensitive determination of eight sulfonamides (SAs) in shrimp. Electrospraying was selected for electrode modification because it can generate the well dispersion of G/PANI nanocomposites on the electrode surface. Prior to electrochemical detection, eight SAs were completely separated within 7min by using reversed phase UPLC (C4) with mobile phase containing 70:25:5 (v/v/v) of potassium hydrogen phosphate (pH 3):acetonitrile:ethanol. For amperometric detection, the detection potential acquired from hydrodynamic voltammetry was found to be +1.4V. Under optimal conditions, a wide linearity and low limit of detection were obtained for eight SAs in the range of 0.01–10µgmL−1 and 1.162–6.127ngmL−1, respectively. Compared to boron-doped diamond (BDD) electrode, a G/PANI-modified screen-printed carbon electrode offered higher sensitivity with lower operating cost. To determine SAs in shrimp samples, solid-phase extraction was used to clean up and preconcentrate the samples prior to UPLC separation. To validate this developed method, a highly quantitative agreement was accomplished with UPLC–UV system. Thus, this proposed system might be an alternative approach for rapid, inexpensive, and sensitive determination of SAs in shrimps. [ABSTRACT FROM AUTHOR]

Label-free electrochemical sensors have gained popularity as point-of-care devices because they do not require complicated labeling procedures. However, they have difficulties detecting multiple analytes simultaneously. In this study, we developed a novel label-free electrochemical immunosensor on an origami paper–based analytical device (oPAD) for the simultaneous detection of quinolone antibiotics, in which norfloxacin (Nor) and enrofloxacin (Enr) were used as a model. The oPAD was designed with two antibody zones, each zone contains different antibodies. The oPAD has two thionine- and ferrocenecarboxylic acid-coated reagent zones, as redox species, which will generate the response current signals for the detection of quinolone antibiotics. The simultaneous current responses of thionine and ferrocenecarboxylic acid decreased proportionately when exposed to Nor and Enr concentrations, respectively. Under optimal conditions, this device provided linear range at concentrations of 0.01–10 µg/mL for the detection of Nor and Enr and limit of detection was calculated as 2.02 and 1.70 ng/mL, respectively. Moreover, this device demonstrates performance comparable to standard methods for the simultaneous detection of Nor and Enr in milk, honey, and fish. Therefore, label-free electrochemical immunosensors provide a highly potent, inexpensive, and portable method for detecting multiple quinolone antibiotics simultaneously on a single device. [Display omitted] • Origami immunosensor was developed for simultaneous detection without labeling. • The oPAD can specifically analyze quinolone residues at the ng/mL level. • Norfloxacin and enrofloxacin in real food samples are accurately estimated. [ABSTRACT FROM AUTHOR]

We report for the first time a highly sensitive and rapid quantitative method for the detection of Salmonella Typhimurium (S. Typhimurium) using a conductive immunosensor on a paper-based device (PAD). S. Typhimurium monoclonal antibodies (MA) were first immobilized on a paper-based device and then captured by S. Typhimurium. After an immunoreaction on the device, the polyclonal antibody-colloidal gold conjugate (PA-AuNPs) was dropped to bind with S. Typhimurium. After a complete sandwich reaction, a dark red color appeared on the paper-based device, which can be observed by the naked eye for a rapid screening test. The electrical conductivity of PA-AuNPs between the screen-printed electrodes on the paper-based device was also measured for an accurate quantitative analysis. The electrical conductivity correlated well with the concentration of S. Typhimurium, which was controlled by the amount of S. Typhimurium attached to the polyclonal antibody-colloidal gold conjugate. The device showed a linear correlation for the concentration of the S. Typhimurium in the range of 10–108 CFU mL−1 in a logarithmic plot, with an R2 value of 0.9882 and a limit of detection (LOD) as low as 10 CFU mL−1. This simple, highly sensitive, and rapid method for the S. Typhimurium detection was successfully performed within 30 min, and it can be developed into small portable measuring devices in order to facilitate preliminary screening tests. [ABSTRACT FROM AUTHOR]

Hybrid nanocomposite particles composed of a gold core coated with a europium(iii)-chelate fluorophore-doped silica shell (AuNPs@SiO2–Eu3+) have been synthesized and applied as antibody labels in lateral flow immunoassay (LFIA) devices for the determination of human thyroid stimulating hormone (hTSH). Labeling of monoclonal anti-hTSH antibodies with AuNPs@SiO2–Eu3+ nanocomposites allows for both colorimetric and fluorometric observation of assay results on LFIA devices, relying on visible light absorption due to the localized surface plasmon resonance of the Au-core and the fluorescence emission of the Eu(iii)-chelate-modified shell under UV hand lamp irradiation (365 nm), respectively. The possibility for a dual signal readout provides an attractive alternative for LFIAs: instantaneous naked eye observation of the AuNP colorimetric signal as in conventional LFIAs for hypothyroidism detection, and more sensitive fluorescence detection to assess hyperthyroidism. The limits of detection (LOD) for naked eye observation of LFIA devices are 5 μIU mL−1 and 0.1 μIU mL−1 for the colorimetric and fluorimetric detection, respectively. Using the fluorescence detection scheme in combination with a smartphone and digital color analysis, a quantitative linear relationship between the red intensity and the logarithmic concentration of hTSH was observed (R2 = 0.988) with an LOD of 0.02 μIU mL−1. Finally, LFIA devices were effectively applied for detecting hTSH in spiked diluted human serum with recovery values between 100–116%. [ABSTRACT FROM AUTHOR]

3D printing technologies are an attractive for fabricating electrochemical sensors due to their ease of operation, freedom of design, fast prototyping, low waste, and low cost. We report the fabrication of a simple 3D-printed electrochemical sensing device for non-enzymatic detection of creatinine, an important indicator of renal function. To create the 3D-printed electrodes (3DE), carbon black/polylactic acid (CB/PLA) composite filament was used. The 3DE was activated using 0.5 M NaOH via amperometry prior to use to improve electrochemical performance. To give selectivity for creatinine, the activated 3DE was modified with a copper oxide nanoparticle-ionic liquid/reduced graphene oxide (CuO-IL/rGO) composite. The modified 3DE was characterized using microscopy and electrochemistry. Cyclic voltammetry and amperometry were used to evaluate sensor performance. The modified 3DE provided electrocatalytic activity towards creatinine without enzymes. Under optimal conditions, the modified 3DE directly coupled with a portable smartphone potentiostat exhibited the linear detection range of 0.5–35.0 mM, and the limit of detection was 37.3 μM, which is sufficient for detecting creatinine in human urine samples. Furthermore, the other physiological compounds present in human urine were not detected on the modified 3DE. Therefore, the modified 3DE could be a tool for effective creatinine screening in the urine. [Display omitted] • A low-cost 3D-printed electrochemical sensor was developed. • CuO-IL/rGO modified electrode was applied for non-enzymatic creatinine detection. • This sensor offers long-term stability and selectivity for creatinine in urine. • 3D-printed electrochemical sensor might be an alternative tool for kidney disease screening. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has significantly increased the development of the development of point-of-care (POC) diagnostic tools because they can serve as useful tools for detecting and controlling spread of the disease. Most current methods require sophisticated laboratory instruments and specialists to provide reliable, cost-effective, specific, and sensitive POC testing for COVID-19 diagnosis. Here, a smartphone-assisted Sensit Smart potentiostat (PalmSens) was integrated with a paper-based electrochemical sensor to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A disposable paper-based device was fabricated, and the working electrode directly modified with a pyrrolidinyl peptide nucleic acid (acpcPNA) as the biological recognition element to capture the target complementary DNA (cDNA). In the presence of the target cDNA, hybridization with acpcPNA probe blocks the redox conversion of a redox reporter, leading to a decrease in electrochemical response correlating to SARS-CoV-2 concentration. Under optimal conditions, a linear range from 0.1 to 200 nM and a detection limit of 1.0 pM were obtained. The PNA-based electrochemical paper-based analytical device (PNA-based ePAD) offers high specificity toward SARS-CoV-2 N gene because of the highly selective PNA-DNA binding. The developed sensor was used for amplification-free SARS-CoV-2 detection in 10 nasopharyngeal swab samples (7 SARS-CoV-2 positive and 3 SARS-CoV-2 negative), giving a 100% agreement result with RT-PCR. [Display omitted] • PNA-based electrochemical paper-based analytical device was introduced for COVID-19 diagnostic. • The new paper-based analytical device platform of SARS-CoV-2 nucleocapsid gene detection was demonstrated. • This PNA-based electrochemical sensor was applicable to real clinical samples with an amplification-free system. • The proposed sensor provided a high sensitivity and specificity against standard assay (RT-PCR). [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyvinyl alcohol (PVA)/starch composite was modified on cotton thread surface. • This modification could improve entrapment capacity and stability of reagents. • The modified thread was applied as a distance-based colorimetric glucose sensor. • Glucose concentration is directly proportional to the color length of the complex. • Human tear (25 µL) was tested on the sensor for screening diabetes within 120 s. Cotton threads have received significant attention to fabricate colorimetric sensing devices due to their self-microfluidic property. To improve the entrapment capacity and stability of the optically responsive reagents and bioreceptors on thread substrate, polyvinyl alcohol (PVA) composited with starch was modified on thread surface to serve as a detection zone relying on distance-based signaling for colorimetric glucose detection in artificial tear. The modified thread surface was characterized to ensure the desired properties prior to fabrication of glucose sensor by integrating with a 3D printed cassette, and the purple color length of iodine–starch–PVA complex was readily observed by the naked-eye within 120 s using a low sample volume of 25 µL, offering a linearity of 0.1–5.0 mM and detection limit of 0.1 mM, which covers a cut-off glucose level in human tear (<0.5 mM). This device might be an alternative device for early diagnosis and home screening of diabetes in non-invasive manner. [ABSTRACT FROM AUTHOR]

• A single step preparation of flower-like structure of platinum (PtNFs) and reduced graphene oxide (rGO) nanocomposite was successfully demonstrated. • Platinum nanoflowers and reduced graphene oxide nanocomposite (PtNFs/rGO) were simultaneously prepared on screen-printed carbon surface as a novel working electrode. • This PtNFs/rGO electrodes exhibited high electrochemical sensitivity and high analytical performances towards diclofenac sensor. • This system was successfully applied for the determination of diclofenac in human urine samples. A single step preparation of platinum nanoflowers and reduced graphene oxide nanocomposite (PtNFs/rGO) modified electrode was accomplished using cyclic voltammetry (CV). A flower-like platinum structure with the homogeneous distribution of PtNFs/rGO on the screen-printed carbon electrode surface was clearly observed by scanning electron microscopy (SEM). The electrochemical behaviors of PtNFs/rGO electrode were systematically investigated by CV. Comparing with an unmodified electrode, PtNFs/rGO electrode provided 5-fold increase in anodic peak current. This newly fabricated electrode not only accelerated the electron transfer between diclofenac and the electrode surface but also promoted the accumulation of diclofenac on electrode surface leading to enhanced electrochemical sensitivity for the quantitative analysis of diclofenac. By using differential pulse voltammetry (DPV), a calibration curve of diclofenac was linear in a range of 0.1−100 µM, and a limit of detection was found to be 40 nM (S/ N = 3). Eventually, this system was successfully applied for the determination of diclofenac in human urine samples. Image, graphical abstract [ABSTRACT FROM AUTHOR]