Differential Pulse Voltammetry Techniques Research Articles

Innovative electrochemical sensor based on platinum group metal complexes for determination of nitrite: Application for simultaneous detection of nitrite and tartrazine

In the context of this experimental study, new palladium and ruthenium complexes based on a symmetric ligand, named 2E-Peaemp ((3E,3’E)-3,3’-(((piperazine-1,4-diyl bis (ethane-2,1-diyl)) bis (azanediyl)) bis (ethan1-yl-1-ylidene)) bis (6-methyl-2H-pyran-2,4(3 H)-dione), and their hybrid compounds with carbon nanotubes were prepared and characterized. The sensors prepared using a cavity microelectrode (MEC) modified with a mixture of graphite (CG), carbon nanotubes (MWCNT) and the synthesized complexes (Pd-2E-Peaemp and Ru-2E-Peaemp) were applied to detect the pollutants such as Nitrites and Tartrazine separately and simultaneously in aqueous solutions and real samples (Tap water, wastewater and bottled commercial spring water). The detection limits (LODs) determined for nitrites and tartrazine are obtained using MEC/CG-MWCNT-Pd-2E-Peaemp electrode, and the electrochemical measurements demonstrated a sensitive and rapid response in the analysis of these species. LODs are 0.39 µM and 0.11 µM, respectively, within the concentration range of 0–909 µM for nitrites and 0–97 µM for tartrazine. This electrode modified by the palladium complex is also used to simultaneously detect nitrite and tartrazine analytes using the differential pulse voltammetry (DPV) technique, indicating that the proposed sensor can be an interesting alternative tool to measure these species in real samples. The application of this electrode in these natural environments reveals that the developed sensor can detect low concentrations of nitrite (NO2-; trace) without any interference from other ions substances as acetate (CH3COO-), borate (BO3−3), phosphate (PO4−3), dihydrogen ( 2 H+), sulfate (SO4−2), sodium (Na+), hydroxide (OH-), potasium (K+), chloride (Cl-), magnesium (I) ( Mg+), nitrate (NO3-), calcium (Ca2+), carbonate (CO3−2).

Microwave aided synthesis of samarium hafnate pyrochlore-sulphur doped reduced graphene oxide for electrochemical detection of bendiocarb

The current study reports the synthesis of pyrochlore type Sm2Hf2O7 (SHO) and its nanocomposite with sulfur-doped reduced graphene oxide (SR). SHO/SR nanocomposite was synthesized using a simple hydrothermal method followed by a microwave-aided synthetic method. Morphological investigations indicate that long SHO particles are well-aggregated in the wrinkled two-dimensional SR. Modified the glassy carbon electrodes (GCE) using SHO, SR and SHO/SR and evaluated for the electrochemical detection of an insecticide, bendiocarb (BDC). Enhanced electrochemical performance was observed in SHO/SR@GCE compared to SHO and SR. Superior electrochemical performance in SHO/SR could be attributed to enhanced conductivity, surface area and stability. Differential pulse voltammetry (DPV) technique showed good sensitivity, and the observed range is 0.05 to 300 μM with a 0.671 μM limit of detection (LOD). In addition, DPV technique is used for the detection of BDC in tomatoes and cabbage, finding a good percentage recovery (97.12 to 99.47 %) with less than 2.65 % relative standard deviation (RSD). The stability of the SHO/SR@GCE was good, and the current response retention was found to be 88.6 ± 1.93 % even after twenty days. SHO/SR's versatile structure, stability, conductivity, and surface area make it an ideal material for developing pyrochlore-based materials for electrochemical and energy applications.

Eletrochemical evaluation of a sensor modified with tucumã biochar for analysis of environmental samples

In this study, a carbon paste electrode modified with tucumã biochar (EPCM/TB) was produced for the determination of pyridine in industrial effluents. To develop the methodology, different paste proportions were evaluated, and a proportion of 40:30:30 (m/m/m) of graphite:tucumã biochar:binder was selected. Cyclic voltammetry was used to characterize the charge and mass transfer process of the electrochemical system; the reaction occurred with the transfer of two electrons. The reaction was irreversible and controlled by diffusion. The experimental variables such as the supporting electrolyte, pH and instrumental parameters of the differential pulse voltammetry (DPV) technique were evaluated. After the optimization of these parameters, four analytical curves were constructed using DPV to calculate the matrix effect (ME). The analytical curves in the presence of the matrix showed good linearity for the three effluents, with R2 values of 0.991, 0.997 and 0995. The limits of detection (LODs) for effluents 1, 2 and 3 were 34.9, 5.5 and 36.8 nmol/L, respectively. The limits of quantification (LOQs) for effluents 1, 2 and 3 were 116.6 nmol/L, 18.4 nmol/L and 122.6 nmol/L, respectively. The MEs of the three effluent samples showed values above 50.0 %, indicating strong MEs; therefore, the quantification of pyridine was performed using the matrix curves. The method had recoveries close to 100 % for the three effluents. The repeatability and reproducibility studies of the method provided RSD% values below 5 %; therefore, the method has potential application in the quantification of pyridine in textile effluents.

Fabrication of a molecularly imprinted poly(methyl methacrylate) decorated graphite electrode for detection of aloe emodin in Aloe vera

In this work, the authors represent a comprehensive approach for the development and validation of a novel graphite-supported molecularly imprinted poly(methyl methacrylate) electrode for the selective and sensitive detection of aloe emodin (AE) in aloe-based cosmetic products. The electrocatalytic activity of the electrode was evaluated using cyclic voltammetry and differential pulse voltammetry techniques in phosphate buffer saline. Surface morphology, structural characteristics, and imprinting endorsement were investigated using field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, and UV-Vis spectroscopy. Under the optimal conditions, the electrode showed an oxidative differential pulse voltammetry peak at -0.2931±0.011 V (vs. Ag/AgCl, saturated KCl). The current was increased linearly with increasing concentrations of AE from 0.0005 to 350 µM, with a low detection limit of 0.0003 µM. The voltammetric analysis has been validated by reverse-phase high-performance liquid chromatography (RP-HPLC) methods. A partial least square regression model was developed to correlate the results obtained from the proposed system with the reference values obtained by RP-HPLC. The model showed a high prediction accuracy of 95.95 % for the detection of AE in cosmetic samples. The developed electrode provides a low-cost, rapid, easy, and convenient method for the detection of AE in cosmetic products, offering potential benefits for quality control and safety assessment in the cosmetic industry.

CuO@3D graphene modified glassy carbon electrode towards the detection of Orange II and Rhodamine B

Synthetic dyes are illegally used in foodstuffs and cause serious health issues in humans due to their carcinogenic nature. To avoid serious health issues, it is compulsory to detect and remove even the minute quantities of these harmful dyes in foodstuffs. Electrochemical sensors are accredited as an efficient and promising platform for the robust and sensitive determination of food toxins in various foodstuffs. Therefore, an efficient, facile, and competent sensor is devised for the simultaneous detection of Orange II (OR II) and Rhodamine B (RhB) supported by rGO and CuO nanoparticles. The synergism between rGO’s immense surface area and the adsorption properties of CuO enhances selectivity and response time for the detection of OR II and RhB. This work elaborated the synthesis, characterization, and electrochemical behavior of CuO@3DGr electrode towards simultaneous sensing of OR II and RhB. Physicochemical techniques were utilized to validate the fabrication of targeted material. On the other hand, the electrochemical features of the developed sensor were characterized by cyclic voltammetry (CV) and electron impedance spectroscopy (EIS). Differential pulse voltammetry technique was employed to detect simultaneously Orange II and Rhodamine B on the surface of bare (GCE), GO/GCE, CuO/GCE, and CuO@3DGr/GCE. Multi-analyte detection is possible with DPV, a sensitive electrochemical method. Based on each toxin’s specific electrochemical signature, the sensor may generate separate peaks by delivering a sequence of potential pulses and detecting the ensuing current. The parameters which influence the performance of the modified sensor were carefully evaluated. Under ambient conditions, the developed sensor exhibited excellent electrocatalytic activity in oxidation at 0.67 V of OR II and 0.96 V RhB with a low limit of detection 08 nM for OR II and 4.5 nM for RhB in Britton- Robinson buffer (BRB pH:7). The described methodology allowed a robust and fast analysis of food toxins in different foodstuff establishing this sensor as a novel tool for detecting food toxins. Tap water was used to analyze the practical applicability of developed electrode material and suitable results were achieved. These results showed that the as-synthesized novel electrochemical sensor has the potential for ultrasensitive determination and detection of toxins in different foodstuffs.

Assessing the Electrochemical Performance of a Novel Low‐Cost Screen‐Printed Electrode Based on Apis mellifera Beeswax Modified with Vulcan@Chitosan Used for Acetominophen Detection

AbstractThe present work reports the development of a highly sensitive electrochemical platform, constructed using screen printed electrode based on Apis mellifera beeswax (SPWE) – employed as substrate, and its application for acetaminophen (AC) detection. The sensor was produced using graphite ink and varnish glass solubilized in acetone. The SPWE was modified with a dispersion of chitosan (0.5% m/v) − functionalized Vulcan XC72R carbon black (Vulcan@Chitosan). Electrochemical characterization was performed using cyclic voltammetry (−0.7 to +0.8 V vs. pseudo‐graphite) and chronoamperometry in 0.1 mol L−1 KCl in the presence of 1.0 mmol L−1 [Fe(CN)6]3−/[Fe(CN)6]4−. Through the application of differential pulse voltammetry (DPV) using 0.1 mol L−1 PBS at pH 6.5, the proposed SPWE/Vulcan@Chitosan sensor was found to exhibit significant improvements in current response relative to the AC electrochemical detection. The sensor exhibited linear dynamic range of 0.05 to 4.0 μmol L−1 (n= 3), with R2= 0.992 and theorical LOD of 0.013 μmol L−1 (RSD= 3.80%). The AC detection was conducted in real matrices of river water, synthetic urine and synthetic saliva using the DPV technique yielded a mean recovery rate of 103% (RSD= 3.52%), exhibiting a high degree of accuracy. The SPWE/Vulcan@Chitosan electrochemical platform demonstrated high stability, good reproducibility and satisfactory repeatability; the current responses were not affected by the reutilization of the beeswax substrate for the production of new electrode. The findings of this study show that the proposed modified electrode is a simple, low‐cost sensing device which has proven to be highly efficient when applied for the AC detection in different matrices.

A sandwich-type electrochemical sensor based on RGO-CeO2-Au nanoparticles and double aptamers for ultrasensitive detection of glypican-3.

Asandwich-type electrochemical aptasensor for ultrasensitive detection ofglypican-3 (GPC3)was constructed using GPC3 aptamer (GPC3Apt) labelled reduced graphene oxide-cerium oxide-gold nanoparticles (RGO-CeO2-Au NPs) as the signal probe and the same GPC3Apt as the capture probe. The electrochemical redox properties of CeO2 (Ce3+/Ce4+) in the RGO-CeO2-Au NPs indicate the electrochemical signals. When the target GPC3 was present, an "aptamer-protein-aptamer" sandwich structure was formed on the sensing interface due to the specific binding between the protein and aptamers, resulting in an increased electrochemical redox signal detected by differential pulse voltammetry (DPV) technique. Under optimal conditions, the established aptasensor exhibited a logarithmic linear relationship between the current response and GPC3 concentration in the range 0.001-100.0ng/mL, with a minimum detection limit of 0.74pg/mL. Using the spike-recovery tests for measurement of the human serum samples, the recovery was from 99.26 to 114.01%, and the RSD range was 3.04 to 5.34%. Furthermore, the sandwich-type electrochemical aptasensor exhibited excellent performance characteristics such as good stability, high specificity, and high sensitivity, demonstrating effective detection of GPC3 in human serum samples and can be used as a clinical detection tool for GPC3.

A bioinspired porous and electroactive reduced graphene oxide hydrogel based biosensing platform for efficient detection of tumor necrosis factor-α.

Oral cancer is one of the leading cancer types, which is frequently diagnosed at an advanced stage, giving patients a poor prognosis and fewer therapeutic choices. To address this gap, exploiting biosensors utilizing anti-biofouling hydrogels for early-stage oral cancer detection in non-invasive body fluids is gaining utter importance. Herein, we have demonstrated the fabrication of an innovative electrochemical immunosensor for the rapid, label-free, non-invasive, and affordable detection of tumor necrosis factor-α (TNF-α), a biomarker associated with oral cancer progression in artificial saliva samples. The gold screen-printed electrodes (gSPEs) are modified with a green synthesized porous and electroactive reduced graphene oxide (rGO) hydrogel utilizing L-cystine (L-cys) as both in situ reducing and surface functionalization agent, followed by covalent immobilization of anti-TNF-α and blocking of residual sites with bovine serum albumin (BSA) to fabricate the BSA/anti-TNF-α/L-cys_rGO hydrogel/gSPE immunosensing platform. The fabricated platform demonstrates excellent performance, with a low limit of detection of 1.20 pg mL-1, a broad linear range from 1 to 200 pg mL-1, and a high sensitivity of 2.10 μA pg-1 mL cm-2 carried out with differential pulse voltammetry (DPV) technique. Moreover, it exhibits specificity towards TNF-α, even in the presence of potential interferents and other cancer biomarkers. Besides, the biosensor showed good reproducibility and repeatability with a relative standard deviation (%RSD) of 5.11% and 1.85%, respectively. Thus, integrating the L-cys_rGO hydrogel in the immunosensor design offers enhanced performance, paving the way for its application in early-stage oral cancer diagnosis.

In situ and one-step electrodeposition growth of PtNi alloys on Ni foam for electrochemical ammonia-nitrogen sensing

The presence of ammonia-nitrogen in aquatic ecosystems has recently been recognized as a significant threat to public and ecological health. Hence, it is crucial to develop a reliable method for accurately quantifying low levels of this pollutant in the aquatic environment. In this work, PtNi alloys of varying compositions were fabricated via a one-step in-situ electrodeposition process on a Ni foam surface. The electrochemical catalytic performances for the ammonia oxidation reaction have been measured via the cyclic voltammetry (CV) technique. The experimental results demonstrated that the PtNi alloy exhibited the highest catalytic capability with the current density of 21.387 mA cm−2 for the ammonia oxidation reaction, when the ratio of H2PtCl6·6 H2O and Ni(NO3)2·6 H2O was 3:1 with the deposition time of 1500 s. Under the most favorable conditions, the electrochemical detection performance of the PtNi alloy in detecting ammonia-nitrogen has been extensively assessed based on the differential pulse voltammetry (DPV) technique. The experiments confirmed that the PtNi alloy demonstrated an outstanding sensitivity, reaching a remarkable value of 0.0255 mA µM−1, with a broad linear range from 3 µM to 500 µM. The PtNi alloy also demonstrated a remarkable low limit detection of 0.89 µM. In addition, Further evaluation of the anti-interference ability, reproducibility, stability and recovery in real sample analysis including tap water, lake water and sea water revealed that the PtNi alloy exhibited superior performance for detecting ammonia-nitrogen.

Electro‐Oxidation of Ibuprofen and Metoprolol Using a Manganese Oxide Platform

AbstractPharmaceutical compounds, such as ibuprofen and metoprolol, are of increasing concern due to their persistence in the environment and potential adverse effects on human health. In this work, we developed an electrochemical sensor system for the determination of ibuprofen and metoprolol based on a modified manganese oxide nanoparticle (MnO2NPs) on a screen‐printed carbon electrode (SPCE). The characterisation of MnO2NPs modifier was investigated via Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy techniques, Uv/vis spectroscopy, and small‐angle X‐ray scattering spectroscopy. The electrochemical behaviour of the MnO2NPs was studied using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. The optimum experimental conditions were investigated by examining the effects of scan rates, pH on the CV responses, and electrolytes on the DPV response. The MnO2NPs modified electrode demonstrated enhanced catalytic activity in the electro‐oxidation of both ibuprofen and metoprolol. The oxidation peaks of ibuprofen and metoprolol were observed at +1.14 V and +1.46 V, respectively, for the MnO2NPs/SPCE sensor. The sensor's limit of detection was 3.81 pM and 4.6 pM respectively and its linear response was from 0.97–5.82 pM. Furthermore, interference and stability studies were conducted to evaluate the performance of the MnO2NPs/SPCE sensor under optimum conditions, which resulted in a good performance. The proposed sensor was successfully used for the determination of ibuprofen and metoprolol in the application of real water samples.

Highly Specific Non-Enzymatic Electrochemical Sensor for the Detection of Uric Acid Using Carboxylated Multiwalled Carbon Nanotubes Intertwined with GdS-Gd2O3 Nanoplates in Human Urine and Serum.

Herein, the electrochemical sensing efficacy of carboxylic acid functionalized multiwalled carbon nanotubes (C-MWCNT) intertwined with coexisting phases of gadolinium monosulfide (GdS) and gadolinium oxide (Gd2O3) nanosheets is explored for the first time. The nanocomposite demonstrated splendid specificity for nonenzymatic electrochemical detection of uric acid (UA) in biological samples. It was synthesized using the coprecipitation method and thoroughly characterized. The presence of functional groups and disorder in the as-synthesized nanocomposite are confirmed using Fourier transform infrared spectroscopy and Raman spectroscopy. Furthermore, field emission scanning electron microscopy, high-resolution transmission electron microscope, X-ray powder diffraction, and X-ray photoelectron spectroscopy provides a clear understanding of the morphology, coexisting phases, and elemental composition of the as-synthesized nanocomposites. The differential pulse voltammetry technique was utilized to elaborate the electrochemical sensing of UA using a GdS-Gd2O3/C-MWCNT modified glassy carbon electrode (GCE), The sensor showed an enhanced current response by more than 2-fold compared to bare GCE. Also, the sensor's performance was further improved by dispersing the nanocomposite in an ionic liquid with the exceptional reproducibility (SD = 0.0025, n = 3). The fabricated UA sensor GdS-Gd2O3/C-MWCNT/IL/GCE demonstrated a wide linear detection range from 0.5-30 μM and 30-2000 μM, effectively covering the entire physiological range of UA in biological fluids with a limit of detection (LOD) of 0.380 μM (+3SD of blank) and a sensitivity of 356.125 μA mM-1 cm-2. Moreover, the electrodes exhibited storage stability for 2 weeks with decrease in zero-day current by only 4.5%. The sensor was validated by quantifying UA in 12 unprocessed clinical human urine and serum samples, and its comparison with the gold standard test yielded remarkable results (p < 0.05). Hence, the proposed nonenzymatic electrochemical UA sensor is selective, sensitive, reproducible, and stable, making it reliable for point-of-care diagnostics.

Comprehensive investigation of zinc and tin-based metal oxides for advanced electrochemical detection of organophosphate pesticides

Different metal oxide (MO) nanomaterials, such as ZnO, SnO2, and nanocomposites of ZnO:SnO2 with various ratios of (1:9), (2:8), and (3:7) were prepared and coated on glassy carbon electrode (GCE). These MOs were tested as sensing material for organophosphate (OP) pesticides detection. Among all MOs, ZnO:SnO2 (1:9) coated GCE increases redox peak current at different buffer solutions with varying pH compared to bare GCE. Moreover, among these pH values, ZnO:SnO2 (1:9) coated GCE significantly enhanced the redox peak at pH 6.2, emphasizing optimal electrochemical conditions for the given pesticides. The morphological, elemental composition, metal ions-functional group interation, and crystallinity of different MO nanocomposites were examined using field-emission scanning electron microscopy (FESEM), fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectrum (EDX), and X-ray diffraction (XRD), respectively. The modified GCE with ZnO:SnO2 (1:9) showed an excellent performance during the electrochemial sensing of the diazinon (DiZn) pesticide. Therefore, detailed study was carried out for the sensing of DiZn. Furthermore, the electrochemical behavior of the ZnO:SnO2 (1:9) coated GCE was evaluated using cyclic voltammetry (CV) with 0.5 mL (5 mM) potassium ferrocyanide, resulting in a pronounced increase in anodic and cathodic peak potentials (Epa = 0.423 V, Epc = 0.1945 V) and currents (Ipa = 9.867 × 10-5 mA, Ipc = -7.993 × 10-5 mA). In addition, electrochemical impedance spectroscopy (EIS) demonstrated a reduction in charge transfer resistance for the coated ZnO:SnO2 (1:9) GCE. Differential pulse voltammetry (DPV) further showed a linear relationship between current and pesticide concentration, with a high correlation coefficient (R2 = 0.996), low limit of detection (LOD = 0.0133 mM) and low limit of quantification (LOQ = 0.0405 mM). Real samples, including tap and seawater, were analyzed to validate the method’s applicability. Additionally, chronoamperometry with a step potential of 1.2 V indicated high sensitivity for DiZn detection, with a sensitivity of 0.23 mA mM−1 cm−2. Finally, the stability of the ZnO:SnO2 (1:9) coated GCE was confirmed through recyclability tests over three cycles using CV and DPV techniques, ensuring its robustness for practical applications in pesticide detection.

Development of ZnO-Pd/Bi2O3 nanocomposite modified carbon paste electrode as a sensor for the simultaneous determination of piroxicam and naproxen

For the first time, an electrochemical sensor was introduced by synthesizing a ZnO-Pd/Bi2O3 nanocomposite into a carbon paste electrode (CPE). The sensor was utilized to simultaneously measure both piroxicam (PIR) and naproxen (NAP). The synthesized nanocomposite’s characteristics were scrutinized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Chronoamperometry, cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry (DPV) techniques were applied to study the electrochemical behavior of the modified electrode in aqueous solutions. A significant increase in the peak current response of PIR and NAP was observed with the ZnO-Pd/Bi2O3 nanocomposite modified carbon paste electrode (ZnO-Pd/Bi2O3/CPE) compared to the bare CPE. Through the DPV technique, ZnO-Pd/Bi2O3/CPE achieved the linear range of 0.3 to 1200 μM with the limit of detection (LOD) of 0.092 μM for PIR and the linear range of 0.5 to 900 μM with the LOD of 0.155 μM for NAP. Also, the limit of quantification (LOQ) for PIR and NAP has been calculated as 0.305 and 0.514 μM, respectively. The comprehensive analysis of real samples demonstrated the precise detection of PIR and NAP in wastewater, tablets, urine, and tap water, highlighting the broad applicability and reliability of the developed sensor in diverse real-world scenarios.

A wide linear range and highly sensitive electrochemical reduction of environmental hazard (p-Nitrotoluene) using carbon-based hybrid composite (Ti3C2TX@MnCo2O4)

The electrochemical sensor is receiving much attention because of the evolving on-time sensing technology. It is crucial to develop new catalysts for electrochemical sensor applications with favorable physicochemical, electrocatalytic properties and good conductivity to meet the demands of on-time monitoring applications. The excellence of this research work is the preparation of Ti3C2TX@MCO nanocomposite by ultra-sonication method for the sensing of p-Nitrotoluene (p-NT). The prepared electrode material exhibits excellent electrocatalytic properties towards the sensing of p-NT compared with other electrodes. The p-NT was quantified by Differential Pulse Voltammetry (DPV) and Amperometric (i-t) techniques. The good linear range was observed by DPV (3–1860 μM) and i-t method (0.18 – 4170 μM). The calculated limit of detection (LOD) from DPV and i-t methods are 93.5 and 35.1 nM, respectively. The sensitivity values calculated from DPV, and i-t methods are 1.68 µA/µM. cm2 and 1.71 µA/µM. cm2, respectively. The proposed sensor system exhibits better selectivity, reproducibility, repeatability and stability for sensing of p-NT. A real time p-NT detection study was conducted using environmental water samples.

Creative synthesis of pH-dependent nanoporous pectic acid grafted with acrylamide and acrylic acid copolymer as an ultrasensitive and selective riboflavin electrochemical sensor in real samples

In current research, an innovative pectic acid was grafted with poly (acrylamide-co-acrylic acid) [PA-g-poly (AAm-co-AA)] nanoporous membrane using a free radical-mediated grafting copolymerization process. The optimized parameters for the grafting copolymerization reaction such as initiator concentration, monomer concentrations, polymerization reaction time, and temperature were studied. Additionally, the solid content, graft percentage, and conversion were calculated. The unique polymeric membrane was characterized using Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetry (TG), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) supported by energy dispersive X-ray spectroscopy (EDX). The formulated novel PA-g-poly (AAm-co-AA) had a nanoporous structure with a diameter of 113 nm. pH-dependent swelling and biodegradation measurements were also studied. The electrochemical characterizations of PA-g-poly (AAm-co-AA) were conducted through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Furthermore, the screen-printed electrode (SPE) was modified with pure PA and the new generation of its grafted polymeric nanoparticles to detect and quantify the concentration of riboflavin (RF) in real samples using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The modified electrode showed two linear concentration ranges from 0.01 - 2 nM and 2 – 90 nM with low detection limits (LODs) of 0.004 and 0.97 nM, respectively, demonstrating high sensitivity. Besides, the fabricated sensor exhibited more selectivity, simplicity, great reproducibility, repeatability, and good stability. Finally, the PA-g-poly (AAm-co-AA)-modified SPE based sensor was effectively used in real sample analysis of egg yolk, milk, and vitamin B2 drugs with good recovery rates.

Sensitive and selective determination of upadacitinib using a custom-designed electrochemical sensor based on ZnO nanoparticle-assisted molecularly imprinted polymer.

Upadacitinib (UPA) is a selective and reversible oral Janus kinase (JAK) 1 inhibitor and is of great importance in treating inflammatory bowel disease (Zheng et al., Int Immunopharmacol 126:111229, 2024; Foy et al., JAAD Case Rep 42:20-22, 2023). Although there are limitations to the effectiveness of UPA, it has received positive responses in clinical trials and is approved for the treatment of atopy dermatitis (AD) (Li et al., Int Immunopharmacol 125:111193, 2023). In this study, a nanoparticle-doped molecularly imprinted polymer (MIP)-based electrochemical sensor was developed for sensitive and selective detection of UPA. The developed sensor was designed as a thin film layer using the photopolymerization method on the surface of the prepared nanoparticle-doped polymerization solution glassy carbon electrode (GCE). Various nanoparticles, such as multi-walled carbon nanotube, titanium dioxide, oxide, and zinc oxide (ZnO) nanoparticles, were the most suitable for UPA. Surface characterization of the developed sensor was done by scanning electron microscopy (SEM), and electrochemical characterization was done by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The quantitative analysis of UPA was performed in 5.0mM [Fe (CN)6]3-/4- solution using the differential pulse voltammetry (DPV) technique. Under optimum conditions, the calibration range was between 0.1 and 1pM. The limit of detection (LOD) and limit of quantification (LOQ) were calculated as 0.005pM and 0.017pM, respectively. The sensor's accuracy was proven by performing a recovery study in serum. The sensor's selectivity was also evaluated using common interfering substances such as KNO3, CaCl2, Na2SO4, uric acid, ascorbic acid, dopamine, and paracetamol. According to the results obtained, the performance of the designed sensor was found to be quite sensitive and selective in determining UPA. The developed UPA-ZnO/3-APBA@MIP-GCE sensor showed high sensitivity and selectivity towards UPA. In addition, the selectivity, the most important feature of the MIP-based sensor, was confirmed by imprinting factor (IF) calculations using tofacitinib (TOF) and ruxolitinib (RUX). The sensor's unique selectivity is demonstrated by its successful performance even in the presence of UPA impurities.

Ultrasonically assisted fabrication of electrochemical platform for tinidazole detection

Based on sonochemistry, green synthesis methods play an important role in the development of nanomaterials. In this work, a novel chitosan modified MnMoO4/g-C3N4 (MnMoO4/g-C3N4/CHIT) was developed using ultrasonic cell disruptor (500 W, 30 kHz) for ultra-sensitive electrochemical detection of tinidazole (TNZ) in the environment. The morphology and surface properties of the synthesized MnMoO4/g-C3N4/CHIT electrode were characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscope (TEM). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were utilized to assess the electrochemical performance of TNZ. The results indicate that the electrochemical detection performance of TNZ is highly efficient, with a detection limit (LOD) of 3.78 nM, sensitivity of 1.320 µA·µM−1·cm−2, and a detection range of 0.1–200 μM. Additionally, the prepared electrode exhibits excellent selectivity, desirable anti-interference capability, and decent stability. MnMoO4/g-C3N4/CHIT can be successfully employed to detect TNZ in both the Songhua River and tap water, achieving good recovery rates within the range of 93.0 % to 106.6 %. Consequently, MnMoO4/g-C3N4/CHIT’s simple synthesis might provide a new electrode for the sensitive, repeatable, and selective measurement of TNZ in real-time applications. Using the MnMoO4/g-C3N4/CHIT electrode can effectively monitor and detect the concentration of TNZ in environmental water, guiding the sewage treatment process and reducing the pollution level of antibiotics in the water environment.

The electrochemical properties of bimetallic silver-gold nanoparticles nano film's

Electrode modification has been one of the most active areas of interest in electrochemistry research. Hence, the investigation of the effects of chemically and electrochemically modified GCE nano-films on the NPs electrochemical properties. The electrochemistry of nano-films of Ag NPs, Au NPs and bimetallic Ag-Au (1:2) NPs of chemical citrate reduction synthesis drop coated (DCT) and electro-deposition method (EDP) are reported. The Chemically synthesized NPs were confirmed through FT-IR, UV–visible, XRD and SEM techniques while electro-deposited NPs were ascertained by double-pulsed chrono-amperometry and electrochemical impedance spectroscopy (EIS). The nano films; GCE/Ag NPs, GCE/Au NPs and GCE/Ag-Ag (1:2) NPs in 0.1 M HCl supporting electrolyte were studied via Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) techniques. Generally the DCT nano films were electrochemically superior to the EDP film in terms of current intensities and GCE/Ag-Au (1:2) NPs showed enhanced α (0.019), ks (0.01 s−1), Q (3.6 × 10−9 C), Γ (5.3 × 10−13molescm−2) and D (1.31 × 10−1 cm2s−1), indicating better physicochemical properties for possible sensing applications compared to electro-deposited GCE nano-films.

Screen-printed electrodes decorated with low content Pt–Ni microstructures for sensitive detection of Zn(II), ascorbic acid and paracetamol in pharmaceutical products and human blood samples

In this study, we report for the first time, a method for simultaneous detection of paracetamol (PA) and its toxic impurities, 4-aminophenol (4-AP), as well as commonly co-formulated drugs, ascorbic acid and zinc (AA and Zn(II)), using screen-printed electrodes (SPEs) as a sensing platform. To improve the electrochemical performance of the SPEs, these are decorated with platinum and nickel microstructures (Pt–Ni), using a simple electrodeposition technique. The structures and morphologies of the synthesized Pt–Ni/SPE electrode were confirmed by FE–SEM, TEM, EDX, XRD and AFM measurements. Furthermore, electrochemical characterization of the as-prepared sensor was investigated using cyclic voltammetry and electrochemical impedance spectroscopy methods. Under optimum conditions, the content of 4-AP, PA, AA and Zn(II) was quantified using cyclic voltammetry, differential pulse voltammetry and square-wave voltammetry techniques. The designed sensor exploits a dual effect, leveraging the efficiency of Pt for Zn(II) detection and Pt–Ni for the detection of 4-AP, AA, and PA. On one hand the as-prepared Pt–Ni/SPE sensor exhibits a linear response towards 4-AP and PA, ranging from 0.5 to 200 μM for both, with detection limits of 0.33 µM and 0.23 µM (S/N = 3) for 4-AP and PA, respectively. On the other hand, it demonstrates a linear response towards PA, AA, and Zn(II), ranging from 0.01 to 0.8 μM for Zn(II), 10 to 1800 μM for AA, and 0.5 to 200 μM for PA, with detection limits of 0.004 µM, 9.0 µM, and 0.15 µM for Zn(II), AA, and PA, respectively. Crucially, the as-fabricated sensor, with its remarkable reproducibility, recovery, long-term stability, and anti-interference capabilities, effectively quantified 4-AP, PA, Zn(II) and AA in both pharmaceutical formulations and human plasma samples.

A novel enzymeless electrochemical sensor based on Ni(OH)2–NiO(OH) nanoelectrocatalyst for sensitive and selective detection of uric acid in PBS simulated body fluid

Neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, and Huntington's disease are increasing worldwide. Therefore, the development of a low-cost, highly stable, and portable device for rapid and accurate risk assessment of relevant biomarkers, especially uric acid (UA), by electrochemical detection is currently attracting much attention. Herein, an electrochemical enzymeless UA sensor based on highly active Ni(OH)2–NiO(OH) nanoelectrocatalyst decorated on polyaniline–carbon nanotubes (PANI-CNTs) nanocomposite film, which was modified on a commercial screen-printed carbon electrode (SPCE) by electrodeposition method for sensitive and selective detection of UA. The sensing behavior of the modified electrode (named Ni(OH)2–NiO(OH)/PANI-CNTs/SPCE) is examined in a simulated body fluid (phosphate buffer solution-PBS, 0.01 M, pH 7.4) using differential pulse voltammetry (DPV) technique. The obtained results showed that the Ni(OH)2–NiO(OH)/PANI-CNTs/SPCE electrode exhibited outstanding electrocatalytic performance for the detection of UA at low potential (0.33 V vs. Ag/AgCl) without exhibiting interfering signals of dopamine (DA), glucose (Glu), ascorbic acid (AA) and urea. The sensor exhibited extra high sensitivity (386.8 μA mM−1 cm−2), high selectivity, good reproducibility, and durable stability with the ability to detect UA at both low (5–100 μM) and high (100–800 μM) levels with a very low detection limit down to 0.11 μM (individual detection of UA) and 0.29 μM (detection of UA in presence of DA) in a simulated body fluid. The recovery test using the proposed electrochemical sensor showed a high recovery percentage (>99.81 %), making it a viable option for practical applications.