Modified Screen Printed Carbon Electrode Research Articles

Expression of scFv-anti-CHIKV-E2 in Escherichia coli with chaperones Co-expression, and its functional assay by electrochemical immunosensor.

Single Chain Variable Fragment (scFv), a small fragment of antibody can be used to substitute the monoclonal antibody for diagnostic purposes. Production of scFv in Escherichia coli host has been a challenge due to the potential miss-folding and formation of inclusion bodies. This study aimed to express anti-CHIKV E2 scFv which previously designed specifically for Asian strains by co-expression of three chaperones that play a role in increasing protein solubility; GroEL, GroES, and Trigger Factor. The scFv and chaperones were expressed in Origami B E. coli host under the control of the T7 promoter, and purified using a Ni-NTA column. Functional assay of anti-CHIKV-E2 scFv was examined by electrochemical immunosensor using gold modified Screen Printed Carbon Electrode (SPCE), and characterized by differential pulses voltammetry (DPV) using K3[Fe(CN)6] redox system and scanning microscope electron (SEM). The experimental condition was optimized using the Box-Behnken design. The results showed that co-expression of chaperone increased the soluble scFv yield from 54.405 μg/mL to 220.097 µg/mL (~5×). Furthermore, scFv can be used to detect CHIKV-E2 in immunosensor electrochemistry with a detection limit of 0.74048 ng/mL and a quantification limit of 2,24388 ng/mL. Thus, the scFv-anti-CHIKV-E2 can be applied as a bioreceptor in another immunoassay method.

Thiol-based chemically modified carbon screen-printed electrode for simultaneous quantification of trace level Pb(II) and Cd(II).

Present work reports, the development of a novel electrochemical sensor based on a diazonium-coupling reaction and covalent attachment of the -NH2 group of cysteamine (Cyst) on screen-printed carbon electrode (SPCE), for simultaneous determination of Pb(II) and Cd(II). Initially, the in-situ generated 4-carboxyphenyl (4-CP) diazonium salt was electro-grafted to generate 4-CP/SPCE, followed by covalent bonding of terminal carboxylic group of 4-CP with -NH2 group of Cyst to give Cyst/4-CP/SPCE. The modified electrode showed an enhanced selectivity and sensitivity toward the quantification of Pb(II) and Cd(II) using square wave anodic stripping voltammetry (SWASV) without mutual interference. Under optimal experimental conditions, the newly designed sensor showed a wide linear range of 0.01µM to 0.7µM. The limit of detection (LOD) obtained was 0.882nM (0.09 ppb) and 0.65nM (0.134ppb) for Cd(II) and Pb(II), respectively. The modified SPCE exhibited good stability, selectivity, and reproducibility. Furthermore, the sensor was successfully applied for the determination of Pb(II) and Cd(II) ions in water samples which illustrated excellent recoveries in different spiked samples and the results were in line with the standard ICP-AES analysis.

Portable glucose detector based on nickel oxide modified Screen Printed Carbon Electrode (SPCE)

A portable and low-cost system prototype for glucose detector based on LMP91000EV M potentiostat has been created. Characterization of Screen-Printed Carbon Electrodes (SPCE) without modification (bare SPCE) and modified nickel oxide (NiO/SPCE) was carried out with a commercial potentiostat to see the effect of nickel oxide in detecting glucose. Through the electrochemical impedance spectroscopy method, the Rct value of 1,276.79 Ω is obtained for NiO/SPCE and 429.06 Ω for bare SPCE, so that NiO/SPCE has a slower electron transfer rate. Meanwhile, through the cyclic voltammetry method, the surface-active electrode area is 7.1×10-2cm2 for NiO/SPCE and 6.9×10-2 cm2 for bare SPCE, so that NiO/SPCE is more sensitive in detecting glucose. When the glucose concentration is varied, the Limit of Detection (LOD) and Limit of Quantitation (LOQ) values of NiO/SPCE are smaller, specifically 1.807 mM and 6.024 mM than bare SPCE, specifically 2.629 mM and 8.762 mM, so NiO/SPCE is more sensitive. When the scan rate is varied, the gradient value of NiO/SPCE is smaller, specifically -8.14×10-4 mA s/mV than bare SPCE, specifically -9.62×10-4 mA s/mV, so NiO/SPCE is not more sensitive. Next, comparing a prototype system that Trans Impedance Amplifier (TIA) gain is varied and a commercial potentiostat. As a result, the cyclic voltammogram per cycle on commercial potentiostat is more stable. The smaller the TIA gain on the system prototype, the more stable it is, this is because the noise that is amplified is getting smaller.

Disposable biosensor based on ionic liquid, carbon nanofiber and poly(glutamic acid) for tyramine determination

In this study, an electrochemical biosensor based on carbon nanofibers (CNF), ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (IL), poly(glutamic acid) (PGA) and tyrosinase (Tyr) modified screen printed carbon electrode (SPE) was constructed for tyramine determination. Optimum experimental parameters such as CNF and IL amount, polymerization conditions of glutamic acid, enzyme loading, pH of test solution and operating potential were explored. The construction steps of the Tyr/PGA/CNF−IL/SPE were pursued by scanning electron microscopy and cyclic voltammetry. The Tyr/PGA/CNF−IL/SPE biosensor exhibited linear response to tyramine in the range of 2.0 × 10−7 – 4.8 × 10−5 M with a low detection limit of 9.1 × 10−8 M and sensitivity of 302.6 μA mM−1. The other advantages of Tyr/PGA/CNF−IL/SPE include its high reproducibility, good stability and anti-interference ability. The presented biosensor was also applied for tyramine determination in malt drink and pickle juice samples and mean analytical recoveries of spiked tyramine were calculated as 100.6% and 100.4% respectively.

A highly sensitive electrochemical sensor based on poly(3-aminobenzoic acid)/graphene oxide-gold nanoparticles modified screen printed carbon electrode for paraquat detection

Herein, a modified screen printed carbon electrode (SPCE) based on a composite material, graphene oxide-gold nanoparticles (GO-AuNPs), and poly(3-aminobenzoic acid)(P3ABA) for the detection of paraquat (PQ) is introduced. The modified electrode was fabricated by drop casting of the GO-AuNPs, followed by electropolymerization of 3-aminobenzoic acid to achieve SPCE/GO-AuNPs/P3ABA. The morphology and microstructural characteristics of the modified electrodes were revealed by scanning electron microscopy (SEM) for each step of modification. The composite GO-AuNPs can provide high surface area and enhance electroconductivity of the electrode. In addition, the presence of negatively charged P3ABA notably improved PQ adsorption and electron transfer rate, which stimulate redox reaction on the modified electrode, thus improving the sensitivity of PQ analysis. The SPCE/GO-AuNPs/P3ABA offered a wide linear range of PQ determination (10−9–10−4 mol/L) and low limit of detection (LOD) of 0.45 × 10−9 mol/L or 0.116 µg/L, which is far below international safety regulations. The modified electrode showed minimum interference effect with percent recovery ranging from 96.5% to 116.1% after addition of other herbicides, pesticides, metal ions, and additives. The stability of the SPCE/GO-AuNPs/P3ABA was evaluated, and the results indicated negligible changes in the detection signal over 9 weeks. Moreover, this modified electrode was successfully implemented for PQ analysis in both natural and tapped water with high accuracy.

Graphene oxide-manganese oxide composite as an electrocatalyst for simultaneous detection of manganese- and chromium-contaminated water.

The development of asensitive and selective electrochemical sensor for simultaneous quantification of manganese (Mn(II)) and chromium (Cr(VI)) using composite of graphene oxide(GO) and manganese oxide modified screen printed carbon electrode (GO-Mn2O3/SPCE) is reported for the first time. The good sensing performance is achieved by mixing GO prepared by modified Hummer's method (GO-H) with proper particle size of Mn2O3 (241 nm). The mechanism of this sensor is based on the formation of Mn-O and Cr-O on the modified electrode with assistance of oxygen moieties provided by both Mn2O3 NPs and GO. The analytical performances were investigated by measuring electrochemical signal of Mn(II) and Cr(VI) by using square-wave cathodic stripping voltammetry (SWCSV). This sensor holds low electrode-to-electrode variation (relative standard deviation (RSD) < 4%) with a good limit of detection (LOD) at about 6.67 and 11.20 μg⋅L-1 for Mn(II) and Cr(VI), respectively. Applicability of this sensor was demonstrated by measuring Mn(II) and Cr(VI) in tap water samples with recovery of 90.77-103.45% and 82.34-103.73% for Mn(II) and Cr(VI) determinations, respectively. With the contribution of both GO and Mn2O3 as electrocatalysts, this developed sensor iscapable to be usedfor water quality monitoring in real samples.

Voltammetric determination of doxycycline in feedstock using modified carbon screen-printed electrode.

In this work, we describe the development of an electrochemical sensing platform that employs electrochemically reduced graphene oxide (ErGO) and gold (Au) deposited on a screen-printed carbon electrode (SPCE) to synthesize Au/ErGO/SPCE for the determination of the antibiotic drug doxycycline (DC). A modified Hummer's approach was adopted to initially prepare graphene oxide, which was then characterized by using powder XRD, FTIR, and UV spectroscopy before being utilized for modification on SPCE. Cyclic voltammetry was performed to form ErGO on SPCE to give ErGO/SPCE followed by electrodeposition of gold to get a final modified electrode Au/ErGO/SPCE. The effect of experimental conditions, like scan rate and pH on the electrochemical behavior of DC for Au/ErGO/SPCE, was evaluated. Square wave voltammetry (SWV) and cyclic voltammetry (CV) measurements were used to assess the electro-oxidation of DC on Au/ErGO/SPCE, and the electrochemical reaction conditions were also optimized. Furthermore, Au/ErGO/SPCE-based electrochemical sensors showed good recovery and high accuracy for DC determination in the complex food matrix and blood serum. The limit of detection (LOD), the limit of quantification (LOQ), and the linear calibration range of DC on Au/ErGO/SPCE under optimum experimental conditions were 0.124µm, 0.415µm, and 1-100µm respectively, with high sensitivity of 0.194 μA μM-1cm-2. Finally, the proposed electrochemical sensing platform was effectively used to determine low DC concentrations in real samples such as chicken flesh and blood serum, indicating its wide range of applications in quality control.

MoS₂ Modified Screen Printed Carbon Electrode Based Flexible Electrochemical Sensor for Detection of Copper Ions in Water

Heavy metal ions (HMI), such as Cu <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{2}+}$ </tex-math></inline-formula> , are harmful to the environment and our health. Such ions are typically measured using glassy carbon electrode (GCE)-based electrochemical sensors developed on rigid substrates. However, several emerging applications require such sensors on flexible, and even disposable, substrates. Herein, we present a molybdenum disulfide (MoS2)-modified screen-printed carbon electrode (SPCE)-based flexible electrochemical sensor for the detection of copper ions in the water. The sensor exhibits excellent response with a limit of detection (LOD) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.43 \mu \text{M}$ </tex-math></inline-formula> for Cu ions in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5 \mu \text{M}$ </tex-math></inline-formula> - 5 mM. The developed sensor is compared with MoS2-modified conventional GCE using electrochemical impedance spectroscopy (EIS). The comparative studies show better linearity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}^{{2}}$ </tex-math></inline-formula> value <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim $ </tex-math></inline-formula> 0.99) for SPCE-based sensor and underline how easily they can detect Cu ions. The interference study, i.e., detection of copper ions in the presence of other HMI-based analytes, also shows the excellent response of SPCE-based flexible electrochemical sensor—thus, demonstrating their practical application is the detection of Cu in water.

Green Synthesis of Silver Nanoparticle Decorated on Reduced Graphene Oxide Nanocomposite using Clinacanthus nutans and Its Applications

A straightforward approach that uses Clinacanthus nutans leaf extract as a bio-reduction agent has been reported to anchor silver nanoparticles onto graphene oxide (rGO-Ag). The nanocomposite was characterized by using ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy, and X-ray diffraction. A qualitative colour transition from yellowish to dark brown confirmed the biosynthesis of rGO-Ag nanocomposite and showed a surface plasmon resonance at 263 nm and 425 nm. Utilizing cyclic voltammetry, the electrochemical characteristics of the rGO-Ag nanocomposite modified screen printed carbon electrodes were examined. The rGO-Ag nanocomposite electrode enhanced anodic current approximately 1.29 times greater compared to silver nanoparticles (AgNPs) and 1.34 times greater compared to graphene oxide (GO). Moreover, rGO-Ag nanocomposites exhibited excellent antibacterial activity against typical Gram-positive (S. aureus) (11.99 ± 0.26 mm) and Gram-negative (E. coli) (11.86 ± 0.29 mm) bacteria. Toxicity was assayed using brine shrimp Artemia salina. The results of hatching and mortality assay demonstrates that AgNPs and rGO-Ag nanocomposite is biocompatible with A. salina at a low dosage (0.001 mg/mL). This work offers a guide for the future synthesis of nanocomposites using green reductants. The as- synthesized nanocomposite shows a promising component for the development of biomedical devices applications.

Towards Embedded Electrochemical Sensors for On-Site Nitrite Detection by Gold Nanoparticles Modified Screen Printed Carbon Electrodes.

The transition of electrochemical sensors from lab-based measurements to real-time analysis requires special attention to different aspects in addition to the classical development of new sensing materials. Several critical challenges need to be addressed including a reproducible fabrication procedure, stability, lifetime, and development of cost-effective sensor electronics. In this paper, we address these aspects exemplarily for a nitrite sensor. An electrochemical sensor has been developed using one-step electrodeposited (Ed) gold nanoparticles (EdAu) for the detection of nitrite in water, which shows a low limit of detection of 0.38 µM and excellent analytical capabilities in groundwater. Experimental investigations with 10 realized sensors show a very high reproducibility enabling mass production. A comprehensive investigation of the sensor drift by calendar and cyclic aging was carried out for 160 cycles to assess the stability of the electrodes. Electrochemical impedance spectroscopy (EIS) shows significant changes with increasing aging inferring the deterioration of the electrode surface. To enable on-site measurements outside the laboratory, a compact and cost-effective wireless potentiostat combining cyclic and square wave voltammetry, and EIS capabilities has been designed and validated. The implemented methodology in this study builds a basis for the development of further on-site distributed electrochemical sensor networks.

Perovskite lanthanum nickelate nanoparticles: As effective modified screen printed carbon electrode for electrochemical detection of trifluoperazine

Perovskite rare earth nickelates have recently been considered excellent electroanalytical features for sensing a variety of target molecules due to their distinctive properties. In this work, a facile coprecipitation synthesis of perovskite lanthanum nickelate (LaNiO3, LNO) nanoparticles was reported along with its application to the electrochemical sensing of trifluoperazine (TFP). The crystal structure and surface morphology of the LNO was characterized by suitable techniques such as X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) with energy-dispersive X-ray (EDX) analysis. The capability of the modified screen printed carbon electrode (LNO/SPCE) to detect TFP in 0.1 M PBS (pH 7) was then examined using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The electrode modified at 0.759 V vs Ag/AgCl and 30 s exhibited the highest peak current (Ip) for TFP electrooxidation. This optimized electrode showed a broad linear range of 0.165–495.5 µM, a low limit of detection (LOD) of 0.017 µM, and a good sensitivity of 0.704 µA µM–1 cm–2. Moreover, the fabricated sensor revealed promising anti-interfering ability, stability, reproducibility, and repeatability toward TFP detection. Finally, the LNO sensor was able to detect TFP in urine and serum samples, and the recovery rates were satisfactory.

Sensitive electrochemical detection of creatinine based on electrodeposited molecular imprinting polymer modified screen printed carbon electrode

Creatinine (Crn) is an important biomarker for kidney function, and early detection could help to avoid end-stage renal disease. In this study, a label-free and ultra-selective platform was developed for Crn detection by modifying the screen-printed carbon electrode (SPCE) with the copper nanoparticle integrated with poly (methyl methacrylate-co-divinylbenzene) molecularly imprinted polymer (Cu2O@MIP) by the electrodeposition method. The synthesized Cu2O@MIP was investigated by transmission electron microscopy (TEM), atomic force microscopy (AFM), fourier transform infrared spectroscopy (FT-IR), cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). In addition, response surface methodology (RSM) is used to optimize the effects of potential and time intervals to increase its sensitivity. Under optimized conditions, Crn was determined in the presence of other interferences to be 2.16 AnM−1cm−2 and the limit of detection (LOD) was 22 nM. The sensor platform showed a response in the nanomolar range of 0–75 nM. The developed non-enzymatic electrochemical sensing responded well to Crn, and is highly specific without any significant compromise to non-specific macromolecules found in urine which presents a promising platform for the development of potable kidney disease detectors.

Electrochemical System for Field Control of Hg2+ Concentration in Wastewater Samples.

The paper presents the validation of an electrochemical procedure for on-site Hg2+ ions determination in wastewater samples using a modified carbon screen-printed electrode (SPE) with a complexing polymeric film based on poly(2,2'-(ethane-1,2-diylbis((2-(azulen-2-ylamino)-2-oxoethyl)azanediyl))diacetic acid) (polyL). Using metal ions accumulation in an open circuit followed by anodic stripping voltammetry, the SPE-polyL electrode presents a linear range in the range of 20 µg/L to 150 µg/L, with a limit of detection (LOD) = 6 µg/L, limit of quantification (LOQ) = 20 µg/L, and an average measurement uncertainty of 26% of mercury ions. The results obtained in situ and in the laboratory using the SPE-polyL modified electrode were compared with those obtained by the atomic absorption spectrometry coupled with the cold vapor generation standardized method, with the average values indicating excellent recovery yields.

Impedance–based haptenation of skin sensitizers with self–assembled monolayer of gold nanoparticles and cysteine modified screen printed carbon electrode

Haptenation of skin sensitizer is indicated because of the covalent attachment of a skin sensitizer to a skin protein. The idea of this research is to explore the haptenation of skin sensitizer with a modified screen printed carbon electrode (SPCE) and a self–assembled monolayer of gold nanoparticles (AuNPs) and cysteine (designated as ACC modified SPCE) using the impedance technique. The ACC modified SPCE was characterized using Fourier–Transform infrared spectroscopy–attenuated total reflectance (FTIR–ATR), atomic force microscopy (AFM), and Energy Dispersive X–Ray Spectroscopy (EDX). The presence of AuNPs and cysteine on the working electrode of the ACC modified electrode was detected by FTIR–ATR and EDX. AuNPs, possessing a homogeneous dot shape, and cysteine was randomly distributed on the carbon surface of SPCE shown by FESEM images. The AFM images indicated the possibility of a monolayer of adsorption of skin sensitizer onto ACC modified SPCE. The ACC modified SPCE has good reproducibility and stability with an RSD of 8.43 %. In addition, the interaction of extreme/strong skin sensitizer with the ACC modified SPCE was discovered with a high value of changes of charge transfer resistance of skin sensitizer (ΔRCTskinsensitizer) when compared to moderate and weak/non skin sensitizers. A total of 9 min was reported to be the optimum contact time of the skin sensitizer onto ACC modified SPCE. The adsorption isotherm studies of skin sensitizers with ACC modified SPCE showed Langmuir isotherm adsorption and spontaneous mechanism. Maleic anhydride (as a model of extreme/strong skin sensitizers) showed a fast–binding rate (18.2149 M−1) with the addition of a slow dissociation rate of 0.0549 M, while glycerol (as a model of weak/non skin sensitizer) showed a slow binding rate of 4.5977 M−1 as a result of a rapid dissociation rate of 0.2175 M. The change in Gibbs free energy (ΔG°) was calculated for ACC modified SPCE with glycerol and maleic anhydride to be at –3.78 × 10+03 kJ/mol and –7.19 × 10+03 kJ/mol, respectively. This study proved that the ACC modified SPCE could be used for routine screening during the early product development stage in qualitative skin sensitization measurements.

Fabrication and Characterization of Clinacanthus nutans Mediated Reduced Graphene Oxide Using a Green Approach

The reduction of graphene oxide (rGO) utilizing green methods such as plants has attracted much attention due to its productivity, eco—friendly features, and cost effectiveness. In the present study, the reflux method was employed to synthesize Clinacanthus nutans (C. nutans) leaf extract mediated rGO using a simple approach. The synthesized rGO was characterized using various spectroscopic and microscopic techniques. The UV-Vis spectrum demonstrated the absorption peak of rGO (270 nm) at distinct locations, while the FTIR analysis demonstrated that the amount of oxygen group in rGO was reduced. The Raman analysis confirms the reduction of GO by a slight increase in the D—band to G—band intensity ratio. The XRD spectra demonstrated that rGO was successfully produced based on the illustrated 2Ɵ angles at a peak of 22.12° with d-spacing of 0.40 nm. FESEM clearly reveals the morphology of rGO that shows crumpled thin sheets, a rougher surface, and a wave—shaped corrugated structure. The reduction of GO was analyzed in the removal of the hydroxyl group and amorphotization of sp2 carbon structures. The C/O ratio in rGO was higher than GO which indicates the small amount of oxygen-containing functional groups were still presented in the reduced graphene oxide. Furthermore, the cyclic voltammetry behavior of a modified screen—printed carbon electrode (SPCE) was measured. The redox reactivity of rGO—SPCE has been affirmed and compared with GO—SPCE and bare—SPCE. The toxicity using A. salina cysts demonstrated that rGO is less toxic compared to GO. The analysis adequately supports the synthesis of rGO and the effective removal of oxygen-containing functional groups from GO. The findings herein illustrate that C. nutans mediates the synthesis of rGO and is a promising eco-friendly substitute to conventional carbon-based fabrication.

Wireless electrochemical sensor for the detection of phytoregulator indole-3-acetic acid using gold nanoparticles and three-dimensional reduced graphene oxide modified screen printed carbon electrode

Plant hormones are important regulatory substances in crop growth and production. In this work, a wireless electrochemical sensor has been successfully established by using gold nanoparticles and three-dimensional reduced graphene oxide (AuNPs-3DGR) modified screen printed carbon electrode (SPCE) to detect plant regulator indole-3-acetic acid (IAA) in plants. AuNPs-3DGR nanocomposite was prepared by reduction of ultrasonic assisted liquid phase dispersed graphene oxide (GO) and Au3+ mixture using hydrothermal method. The composite was modified on SPCE by drop coating, and the wireless portable electrochemical workstation that controlled by smartphone was used to detect IAA with a wider linear ranges (0.25–120.0 μmol/L and 135.0–500.0 μmol/L) and a lower limit of detection (0.15 μmol/L, 3σ/S). After that, this sensor was applied to detect the IAA content in different tissues of mung bean sprouts with satisfactory results. The combination of modified SPCE with small bluetooth workstations and smartphone is very useful to construct portable, low-cost, simple and fast electrochemical sensing platform.

A Unique Oligonucleotide Probe Hybrid on Graphene Decorated Gold Nanoparticles Modified Screen-Printed Carbon Electrode for Pork Meat Adulteration

A Unique Oligonucleotide Probe Hybrid on Graphene Decorated Gold Nanoparticles Modified Screen-Printed Carbon Electrode for Pork Meat Adulteration

The development of disposable electrochemical sensor based on MoSe2-rGO nanocomposite modified screen printed carbon electrode for amitriptyline determination in the presence of carbamazepine, application in biological and water samples

The present attempt developed a simple sensing system based on the modification of screen-printed carbon electrode (SPCE) with MoSe2/reduced graphene oxide (rGO) nanocomposite (MoSe2-rGO/SPCE) to voltammetrically co-detect amitriptyline and carbamazepine. Different techniques such as field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize MoSe2-rGO nanocomposite morphology and structure. Moreover, chronoamperometry, differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV) were utilized to explore the electrochemical oxidation of amitriptyline. Data revealed a great current sensitivity for the MoSe2-rGO/SPCE towards amitriptyline. The peak currents of amitriptyline oxidation on the MoSe2-rGO/SPCE had linear dynamic range (0.02–380.0 μM) and a narrow limit of detection (0.007 μM). The MoSe2-rGO/SPCE was successful in sensing carbamazepine and amitriptyline in real specimens, with appreciable recovery rates.

Non-enzymatic Electrochemical Sensing of 3-Hydroxybutyric Acid by Incorporating Manganese Oxide Modified Electrode and Nitroprusside Electrolyte

The development of 3-hydroxybutyric acid (3-HB) biosensors via electrochemical method is commonly based on the use of enzymes that usually display inherent instability. Here, a novel non-enzymatic 3-HB electrochemical sensor platform by incorporating manganese oxide nanoparticles (Mn2O3 NPs) modified screen printed carbon electrode (SPCE) and sodium nitroprusside (SNP) electrolyte was reported for the first time. The mechanism of this sensor based on the formation of electroactive SNP-HB species with assistance of Mn2O3 catalyst. By the enhanced electroactivity of the complex, 3-HB can be quantitatively measured based on the increased peak current and shifted peak potential in cyclic voltammograms of SNP reduction. SNP concentration and Mn2O3 loading were optimized for maximum current response. The sensitivity of as-prepared sensor system was examined under different pH values (6.4–7.4) in the range of 0–10 mM 3-HB. The highest sensitivity of 39.07 μA·mM−1·cm−2 and 5.84 mV·mM−1 with LOD of 0.5 mM was achieved at pH 7.4 of electrolyte solution. The proposed sensor provided favorable stability and selectivity against various interferents. In addition, the ability to quantitatively detect 3-HB in artificial urine was also demonstrated, suggesting that our sensor can be a promising candidate for practical applications.

Fabrication of Nitrogen-Doped Reduced Graphene Oxide Modified Screen Printed Carbon Electrode (N-rGO/SPCE) as Hydrogen Peroxide Sensor.

In recent years, the electrochemical sensing approach has attracted electrochemists because of its excellent detection process, simplicity, high sensitivity, cost-effectiveness, and high selectivity. In this study, we prepared nitrogen doped reduced graphene oxide (N-rGO) and characterized it using various advanced techniques such as XRD, SEM, EDX, Raman, and XPS. Furthermore, we modified the active surface of a screen printed carbon electrode (SPCE) via the drop-casting of N-rGO. This modified electrode (N-rGO/SPCE) exhibited an excellent detection limit (LOD) of 0.83 µM with a decent sensitivity of 4.34 µAµM−1cm−2 for the detection of hydrogen peroxide (H2O2). In addition, N-rGO/SPCE also showed excellent selectivity, repeatability, and stability for the sensing of H2O2. Real sample investigations were also carried out that showed decent recovery.