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Bisphenol A (BPA), a known endocrine-disrupting chemical, has been the subject of widespread bans in food packaging and baby bottles. Due to the potential health risks associated with BPA exposure, precise detection methods are crucial for toxicity assessments, ensuring food safety, and monitoring environmental pollutants. To address this imperative, we have developed an electrochemical sensor utilizing a composite material composed of copper-organic framework (Cu-MOF), cetyltrimethylammonium bromide (CTAB), and graphene (GN). This modified composite, known as CTAB-GN-Cu-MOF, was successfully synthesized and characterized via SEM, FT-IR, XPS, XRD, Zeta, and Size analyses. The integration of Cu-MOF, CTAB, and GN resulted in a synergistic effect, enhancing the electron transport rate and accumulation efficiency for BPA. This technological advancement led to increased signals in differential pulse voltammetry and a substantial electroactive surface area (0.031 cm2). The sensor exhibited a linear response range from 0.100 to 800 μmol L−1 with a detection limit of 35.0 nmol L−1 (signal-to-noise ratio of 3). The sensitivity was measured at 0.890 μA μM−1 cm−2 within the concentration range of 25.0–800 μmol L−1 and 8.87 μA μmol−1 cm−2 within the range of 0.10–10.0 μmol L−1. The device demonstrated stable and satisfactory recovery rates between 96.56% and 103.88% when detecting BPA in various plastic samples, highlighting its potential for practical applications. An electrochemical sensing platform with good performance based on a CTAB-GN-Cu-MOF modified electrode was fabricated in this paper for simultaneous detection of Bisphenol A (BPA). This modified composite, CTAB-GN-Cu-MOF, was successfully synthesized and characterized via SEM, FT-IR, XPS, XRD, Zeta, and Size analyses. The integration of Cu-MOF, CTAB, and GN resulted in a synergistic effect, enhancing the electron transport rate and accumulation efficiency for BPA. This technological advancement increased signals in differential pulse voltammetry and a substantial electroactive surface area (0.031 cm2). The sensor exhibited a linear response range from 0.100 to 800 μmol L−1 with a detection limit of 35.0 nmol L−1. The device demonstrated stable and satisfactory recovery rates between 96.56% and 103.88% when detecting BPA in various plastic samples, highlighting its potential for practical applications. [ABSTRACT FROM AUTHOR]

We introduced a voltammetric bisphenol A (BPA) sensor based on NiCo2O4/reduced graphene oxide (rGO) nanocomposite loaded on the screen-printed electrode surface (NiCo2O4/rGO/SPE). NiCo2O4/rGO was characterised using various techniques, including X-ray diffraction (×RD), Raman spectroscopy and scanning electron microscopy (SEM). We used differential pulse voltammetry (DPV) to detect BPA concentrations. We evaluated the key analytical features of NiCo2O4/rGO/SPE for the BPA detection and the effects of important experimental parameters on the voltammetric efficiency. The voltammetric response of the proposed electrode was evaluated towards BPA. We demonstrated that the produced electrode has a wide linear dynamic range (0.03 to 475.0 μM) and a detection limit as low as 0.01 μM at S/N = 3. [ABSTRACT FROM AUTHOR]

Hydroxylamine (HA) is a toxic and mutagenic molecule which are in the top list of environmental pollutants. We developed a sensitive HA electrochemical sensor constructed with electrocatalytic performance of magnesium aluminate spinel nanoparticles (MgAl2O4). The electrochemical activity of HA on magnesium aluminate spinel nanoparticles modified screen-printed electrode (MgAl2O4/SPE) was analysed by cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV) and chronoamperometry. According to the findings, the modified electrode had admirable electrocatalytic performance towards HA. As-fabricated electrochemical sensor displayed an unparalleled performance in detection of HA with a low limit of detection (0.035 μM, S/N = 3) in a lengthy linear dynamic range (0.09–375.0 μM). The developed protocol was successful in sensing HA in water specimens, with satisfactory outcomes. [ABSTRACT FROM AUTHOR]

A composite material based on CuFe-ZIF-derived CuFe2O4 nano-microspheres grown in situ and well-ordered on carbon sheets (CS) was prepared and applied for highly effective determination of bisphenol A (BPA). The composite material possessed inherently high redox activity due to the presence of both Cu and Fe ions with various oxidation states (Cu²⁺/Cu⁺ and Fe³⁺/Fe²⁺), high specific surface area, uniform distribution of Cu and Fe ions, and a robust framework imparted by its precursor CuFe-ZIF. This led to increased active sites for electrochemical reactions, improved electron transfer efficiency, and structural integrity during electrochemical cycling. Furthermore, combining CS with CuFe2O4 not only provided a large surface area to support well-ordered CuFe₂O₄ nano-microspheres without aggregation, but also enhanced the conductivity and mechanical stability of the CuFe₂O₄/CS composite. This results in synergistic effects that enhanced the overall performance of the composite material. In addition, both copper and iron are relatively non-toxic and abundant, making CuFe₂O₄/CS safe and cost-effective for large-scale applications. Consequently, the CuFe2O4/CS-modified electrode shows highly efficient electrochemical sensing properties with a wider detection range of 0.009-168 µM and lower detection limit of 0.0027 µM (S/N = 3) compared with most reported BPA sensors. It also has an optimized current at pH 7 which is convenient for real world applications. This CuFe2O4/CS modified electrode as a highly sensitive electrochemical platform can be applied to monitor BPA concentrations in bottled water with good recovery (97.2-102.2%). [ABSTRACT FROM AUTHOR]

Purpose: This study aims to develop an electrochemical sensor for the detection of benzophenone (BP) as an alternative to conventional techniques that are known, expensive, complex and less sensitive. Design/methodology/approach: The developed sensor is a platinum electrode modified with a plasticized polymer film based on ß-cyclodextrin, using PVC as the polymer, PEG as the plasticizer and ß-CD as the ionophore. This sensor is characterized by various techniques, such as optical microscopy, scanning electron microscopy and cyclic voltammetry. This latter is also used for analyzing kinetic processes at the electrode/electrolyte interface and to evaluate the selectivity and sensitivity of the sensor. Findings: The results highlight the performance of our sensor. In fact, it exhibits a linear response extending from 10−19 to 10−13 M, with a correlation coefficient of 0.9836. What is more, it has an excellent detection limit of 10−19 M and a good sensitivity of 21.24 µA/M. Originality/value: The results of this investigation demonstrated that the developed sensor is an analytical tool of choice for the monitoring of BP in the aqueous phase. The suggested sensor is fast, simple, reproducible and inexpensive. [ABSTRACT FROM AUTHOR]

A new electrochemical sensor for the highly sensitive and selective determination of dopamine was developed, based on the use of a glassy carbon electrode modified with cobalt(II) polymer. Both electrochemical and morphological characterizations were investigated. Square wave voltammetry (SWV) was used for the determination of dopamine. From the SWV results obtained on the modified electrode under the optimized conditions, the successive addition of dopamine increased the anodic peak current. The results obtained show a linear response of the electrode modified with Co(II) polymer in a wide concentration range. Each concentration decade is characterized by a new calibration plot with a corresponding mathematical expression. The highest sensitivity (13.182) was obtained for the lowest concentration range, and the detection limit of 0.03 µM, calculated based on the 3 × sb/m criterion, indicates a very high sensitivity and great application potential. When analyzing a real sample, the modified electrode showed good electroanalytical activities in terms of oxidation of dopamine, good anti-interference ability, stability, reproducibility, and potential applicability in commercial pharmaceutical samples. [ABSTRACT FROM AUTHOR]

A pure natural kaolinite (K) was modified by intercalation and grafting into the interlayer space of 1-(2-hydroxyethyl)piperazine (HEP). The resulting organo-inorganic hybrid material (referred as KHEP) was characterised using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and 29Si nuclear magnetic resonance (NMR) techniques. The electrochemical characterisation of K and KHEP materials was carried out by studying the electrochemical behaviour using cyclic voltammetry of [Fe(CN)6]3− ions on the surface of a glassy carbon electrode (GCE) modified with a film of each of these materials (GCE/K and GCE/KHEP). The GCE/KHEP organokaolinite film electrode was successfully applied for the simultaneous detection of Pb(II) and Cu(II) in contaminated media. The peak currents of Pb(II) and Cu(II) obtained under the same optimal conditions on GCE/KHEP were much more intense than those obtained on GCE/K and bare GCE. Under optimal conditions, the influence of the concentration of Cu2+ and Pb2+ ions on the peak currents was studied for several concentration ranges. The obtained linear calibration curves were then used to calculate the different limits of detection (LOD) on the basis of a signal-to-noise ratio of 3. Thus, in simultaneous detection and for the concentration range from 0.02 to 0.12 µmol L−1 (pH accumulation medium 5.0) and for each of the ions analysed, LODs of 1.942 nmol L−1 for Cu(II) and a LOD of 1.072 nmol L−1 for Pb(II) were obtained. The GCE/KHEP sensor developed in this work was successfully applied for the simultaneous detection of Pb(II) and Cu(II) in real samples. ASSWV signal corresponding to the simultaneous detection of Pb2+ and Cu2+ ions recorded on unmodified GCE (black curve), GCE/K; (red curve) and GCE/KHEP (blue curve) in 0.2 mol L−1 NaNO3 (with pH adjusted at 2.5) after 7 min of accumulation in aqueous medium (pH 5.0) of each ion at the concentration at 2.0 µmol L−1. Other experimental conditions are as follows: telec: 80 s, Eelec: − 0.90 V, Potential amplitude: 0.05 V, Step potential (V): 0.005 V and Frequency: 50 Hz. [ABSTRACT FROM AUTHOR]

Effectively detecting catechol (CC) and hydroquinone (HQ) simultaneously is crucial for environmental protection and human health monitoring. In the study presented herein, a novel electrochemical sensor for the sensitive simultaneous detection of CC and HQ was constructed based on an electrochemically reduced graphene oxide (ERGO)-modified multi-walled carbon nanotube paste electrode (MWCNTPE). Scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and electrochemical techniques were utilized to characterize the sensing interface and investigate the sensing mechanism. Under the optimal detection conditions, the oxidation peak currents of CC and HQ show a good linear relationship with their concentrations in the range of 0.4–400 μM with a detection limit of 0.083 μM for CC and 0.028 μM for HQ (S/N = 3). Moreover, the sensor exhibits good performance and can be applied successfully in the simultaneous detection of CC and HQ in tap water samples and urine samples with satisfactory results, indicating its promising application prospects. [ABSTRACT FROM AUTHOR]

In this study, a new and simple glassy carbon electrode modified with carbon nanohorns (SWCNH/GCE) was used for the determination of Cr(VI) in aqueous matrices via adsorptive cathodic stripping voltammetry (AdCSV). The modified electrode was characterized via field emission scanning electron microscopy and cyclic voltammetry, which revealed a homogeneous distribution of spherical agglomerates of SWCNH on the electrode surface. The modification increased the electrochemically active area from 0.10 cm2 ± 0.01 (GCE) to 0.16 cm2 ± 0.01 (SWCNH/GCE). The optimized analytical conditions were as follows: a supporting electrolyte (0.15 mol L−1 HCl), an accumulation potential of 0.8 V versus Ag/AgCl, and an accumulation time of 240 s. Validation of the analytical methodology was performed, obtaining a linear range between 20 and 100 µg L−1, a limit of detection of 3.5 µg L−1, and a limit of quantification of 11.6 µg L−1 with good accuracy and precision. The method was applied to the analysis of spiked tap water samples, and the results were compared using a flame atomic absorption spectrophotometer (FAAS) with no significant statistical differences. [ABSTRACT FROM AUTHOR]

Gold electrode modification with nafion and WO3 has been done for oxalate ion detection. The voltammogram of oxalate ion on the surface gold with and without modification showed a significant difference. This means that the modified gold electrode is sensitive to oxalate ions. The performance of the modified electrode in different pH (5, 7, and 12) in the KCl solution also has been studied using cyclic voltammetry. The range of the measurement is from – 1.0 to + 1.0 at a scan rate of 100 mV s -1. The result showed that the optimum measurement pH is 12 with an anodic peak at 0.143 V and no reduction peak. The measurements of 0, 50, 100, 150, 200, and 250 mg L-1 oxalic ion also have been conducted, showing a linear increase in current. The equation obtained is y = 0.5426 x + 0.9127. In addition, the modified gold electrode showed good selectivity towards oxalate detection, as cyclic voltammetry measurements of some interference components did not produce redox peaks in the oxalate oxidation potential range. These findings indicate that gold electrodes modified with Nafion/WO3 significantly affect the potential development of electrochemical oxalate sensors. [ABSTRACT FROM AUTHOR]

An electrochemical sensor assisted by primer exchange reaction (PER) and CRISPR/Cas9 system (PER-CRISPR/Cas9-E) was established for the sensitive detection of dual microRNAs (miRNAs). Two PER hairpin (HP) were designed to produce a lot of extended PER products, which could hybridize with two kinds of hairpin probes modified on the electrode and initiate the cleavage of two CRISPR/Cas9 systems guided by single guide RNAs (sgRNAs) with different recognition sequences. The decrease of the two electrochemical redox signals indicated the presence of dual-target miRNAs. With the robustness and high specificity of PER amplification and CRISPR/Cas9 cleavage system, simultaneous detection of two targets was achieved and the detection limits for miRNA-21 and miRNA-155 were 0.43 fM and 0.12 fM, respectively. The developed biosensor has the advantages of low cost, easy operation, and in-situ detection, providing a promising platform for point-of-care detection of multiple miRNAs. [ABSTRACT FROM AUTHOR]

CoFe@C was first prepared by calcining the precursor of CoFe-metal–organic framework-74 (CoFe-MOF-74), then an electrochemical sensor for the determination of neohesperidin dihydrochalcone (NHDC) was constructed, which was stemmed from the novel CoFe@C/Nafion composite film modified glassy carbon electrode (GCE). The CoFe@C/Nafion composite was verified by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) was used to evaluate its electrical properties as a modified material for an electrochemical sensor. Compared with CoFe-MOF-74 precursor modified electrode, CoFe@C/Nafion electrode exhibited a great synergic catalytic effect and extremely increased the oxidation peak signal of NHDC. The effects of various experimental conditions on the oxidation of NHDC were investigated and the calibration plot was tested. The results bespoken that CoFe@C/Nafion GCE has good reproducibility and anti-interference under the optimal experimental conditions. In addition, the differential pulse current response of NHDC was linear with its concentration within the range 0.08 ~ 20 µmol/L, and the linear regression coefficient was 0.9957. The detection limit was as low as 14.2 nmol/L (S/N = 3). In order to further verify the feasibility of the method, it was successfully used to determine the content of NHDC in Chinese medicine, with a satisfactory result, good in accordance with that of high performance liquid chromatography (HPLC). [ABSTRACT FROM AUTHOR]

In this research, CuCo2O4 nanorods (CuCo2O4 NRs) were prepared using a simple hydrothermal technique and characterized by using various techniques. Subsequently, a highly sensitive and simple electrochemical sensor was prepared by modifying a screen-printed graphite electrode with CuCo2O4 NRs (CuCo2O4 NRs/SPGE) and applied for the detection of sudan I. The electrocatalytic oxidation of sudan I was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry, and linear sweep voltammetry (LSV). The modification of the electrode surface with CuCo2O4 NRs exhibited the highest electro-catalytic activity towards sudan I oxidation, resulting in an improved sensitivity compared to the unmodified electrode. Based on these findings, we analyzed a screen-printed sensor (CuCo2O4 NRs/SPGE) using DPV for sudan I determination. The sensor demonstrated a linear response ranging from 0.04 µM to 560.0 µM, with a limit of detection (LOD) of 0.01 µM and a sensitivity of 0.097 µM/µA. The suitability of the proposed sensor for sudan I determination in real samples was also demonstrated, with good recovery results ranging from 97.6 to 104.0% and a maximum relative standard deviation (RSD) of 3.5%. [ABSTRACT FROM AUTHOR]

A sensing interface co-constructed from the two-dimensional conductive material (Ag@MXene) and an antifouling cyclic multifunctional peptide (CP) is described. While the large surface area of Ag@MXene loads more CP probes, CP binds to Ag@MXene to form a fouling barrier and ensure the structural rigidity of the targeting sequence. This strategy synergistically enhances the biosensor's sensitivity and resistance to contamination. The SPR results showed that the binding affinity of the CP to the target was 6.23 times higher than that of the antifouling straight-chain multifunctional peptide (SP) to the target. In the 10 mg/mL BSA electrochemical fouling test, the fouling resistance of Ag@MXene + CP (composite sensing interface of CP combined with Ag@MXene) was 30 times higher than that of the bare electrode. The designed electrochemical sensor exhibited good selectivity and wide dynamic response range at PD-L1 concentrations from 0.1 to 50 ng/mL. The lowest detection limit was 24.54 pg/mL (S/N = 3). Antifouling 2D materials with a substantial specific surface area, coupled with non-straight chain antifouling multifunctional peptides, offer a wide scope for investigating the sensitivity and antifouling properties of electrochemical sensors. [ABSTRACT FROM AUTHOR]

An innovative electrochemical sensing method is introduced for dihydroxy benzene (DHB) isomers, specifically hydroquinone (HQ) and pyrocatechol (PCC), employing a zinc-oxide/manganese-oxide/reduced-graphene-oxide (ZnO/MnO2/rGO) nanocomposite (NC) as an electrode modifier material. Comprehensive characterization confirmed well-dispersed ZnO/MnO2 nanoparticles on rGO sheets. Electrochemical analysis revealed the ZnO/MnO2/rGO-NC-based modified electrode possesses low electrical resistance (126.2 Ω), high electrocatalytic activity, and rapid electron transport, attributed to the synergies between ZnO, MnO2 and rGO. The modified electrode demonstrated exceptional electrochemical performance in terms of selectivity for the simultaneous detection of HQ and PCC. Differential pulse voltammetry studies validated the proposed sensor's ability to detect HQ and PCC within linear response ranges of 0.01–115 μM and 0.03–60.53 μM, with detection limits of 0.0055 µM and 0.0053 µM, respectively. Practical validation using diverse water samples showcased excellent percent recovery of HQ and PCC using the ZnO/MnO2/rGO-based electrochemical sensor, underscoring the sensor's potential for real-world applications in environmental monitoring. [ABSTRACT FROM AUTHOR]

A signal-amplified platform was designed to construct a label-free electrochemical aptasensor for lead ions (Pb2+) assay. First, flower-like molybdenum disulfide-supported AuNPs (AuNPs@MoS2) nanocomposites were synthesized and used as substrates for modifying the electrode. The AuNPs@MoS2 material possessed large surface area and superior biocompatibility, which was beneficial to improve the loading amount of the complementary DNA (cDNA) and amplified the response signal. Importantly, the prepared core–shell Pt@Pd bimetallic nanoparticles (Pt@PdNPs) were used to conjugate with redox marker thionine (Thi) and aptamer (Apt) for further signal amplification; the obtained signal probes (Thi-Pt@PdNPs-Apt) were connected by the cDNA assembled on the electrode through DNA hybridization. Differential pulse voltammetry was performed to monitor the signal of Thi. After incubating of aptasensor with Pb2+, the specific recognition of Pb2+ and Apt resulted in the dissociation of aptamer-cDNA complex, thereby the Thi-Pt@PdNPs-Apt separated from the electrode surface and decreased current response was obtained. The prepared electrochemical sensor exhibited linear response to Pb2+ in the range 5.0 × 10−4–100 nM and a detection limit of 1.0 × 10−4 nM was achieved. The sensor was applied to the determination of Pb2+ in actual sample with high sensitivity and accuracy, demonstrating potential applications in heavy metal monitoring. [ABSTRACT FROM AUTHOR]

A comparative analysis of molecularly imprinted polymers based on different synthesis techniques was performed for the recognition of molnupiravir (MOL). The polymerizations were performed with 3-thienyl boronic acid (3-TBA) as a functional monomer by electropolymerization (EP) and with guanine methacrylate (GuaM) as a functional monomer by photopolymerization (PP). Morphological and electrochemical characterizations of the developed sensors were investigated to verify the constructed sensors. Moreover, quantum chemical calculations were used to evaluate changes on the electrode surface at the molecular and electronic levels. The dynamic linear range of both designed sensors under optimized experimental conditions was found to be 7.5 × 10−12–2.5 × 10−10 M and 7.5 × 10−13–2.5 × 10−11 M for EP and PP, respectively. The effect of various interfering agents on MOL peak current was assessed for the selectivity of the study. In the presence of 100 times more interfering agents, the RSD and recovery values were determined. The RSD values of GuaM/MOL@MIP/GCE and poly(Py-co-3-PBA)/MOL@MIP/GCE sensors were found to be 1.99% and 1.72%, respectively. Furthermore, the recovery values of the MIP-based sensors were 98.18–102.69% and 98.05–103.72%, respectively. In addition, the relative selectivity coefficient (k′) of the proposed sensor was evaluated, and it exhibited good selectivity for MOL with respect to the NIP sensor. The prepared sensor was successfully applied to determine MOL in commercial serum samples and capsule form. In conclusion, the developed sensors provided excellent reproducibility, repeatability, high sensitivity, and selectivity against the MOL molecule. [ABSTRACT FROM AUTHOR]

In this work, UiO-66-NH2/GO nanocomposite was prepared using a simple solvothermal technique, and its structure and morphology were characterized using field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). An enhanced electrochemical sensor for the detection of epirubicin (EP) was proposed, which utilized a UiO-66-NH2/GO nanocomposite-modified screen-printed graphite electrode (UiO-66-NH2/GO/SPGE). The prepared UiO-66-NH2/GO nanocomposite improved the electrochemical performance of the SPGE towards the redox reaction of EP. Under optimized experimental conditions, this sensor demonstrates a remarkable limit of detection (LOD) of 0.003 µM and a linear dynamic range from 0.008 to 200.0 µM, providing a highly capable platform for sensing EP. Furthermore, the simultaneous electro-catalytic oxidation of EP and topotecan (TP) was investigated at the UiO-66-NH2/GO/SPGE surface utilizing differential pulse voltammetry (DPV). DPV measurements revealed the presence of two distinct oxidation peaks of EP and TP, with a peak potential separation of 200 mV. Finally, the UiO-66-NH2/GO/SPGE sensor was successfully utilized for the quantitative analysis of EP and TP in pharmaceutical injection, yielding highly satisfactory results. [ABSTRACT FROM AUTHOR]

In this study, a novel nanocomposite of graphene oxide-zinc oxide-manganese (GO-ZnO-M) was successfully synthesized using a modified Hummers method and hydrothermal technique. Enhanced electrochemical performance was observed in the GO-ZnO-M nanocomposite when utilized as an electrode material for the detection of rutin, a flavonoid known for its significant health benefits. The GO-ZnO-M modified electrode demonstrated excellent sensitivity, selectivity, reproducibility, and stability during rutin detection. Furthermore, the sensor exhibited a wide linear detection range and a low detection limit. The practical applicability of the GO-ZnO-M/GCE sensor was assessed by detecting rutin in pharmaceutical tablet samples, yielding satisfactory results. This study highlights the potential of GO-ZnO-M nanocomposites as promising materials for the electrochemical detection of rutin and other biologically significant compounds. [ABSTRACT FROM AUTHOR]

A direct electrochemical sensor based on covalent organic frameworks (COFs)/platinum nanoparticles (PtNPs) composite was fabricated for the detection of ofloxacin (OFX) in water. Firstly, the COF material was synthesized via the condensation reaction of 1,3,5-tris(4-aminophenyl)benzene (TAPB) with terephthalaldehyde (TPA) and integrated with PtNPs by in situ reduction. Then, TAPB-TPA-COFs/PtNPs composite was loaded onto the surface of the glassy carbon electrode (GCE) by drip coating to construct the working electrode (TAPB-TPA-COFs/PtNPs/GCE). The electrochemical performance of TAPB-TPA-COFs/PtNPs/GCE showed a significant improvement compared with that of TAPB-TPA-COFs/GCE, leading to a 3.2-fold increase in the electrochemical signal for 0.01 mM OFX. Under optimal conditions, the TAPB-TPA-COFs/PtNPs/GCE exhibited a wide linear range of 9.901 × 10−3–1.406 µM and 2.024–15.19 µM with a detection limit of 2.184 × 10−3 µM. The TAPB-TPA-COFs/PtNPs/GCE-based electrochemical sensor with excellent performance provides great potential for the rapid and trace detection of residual OFX. [ABSTRACT FROM AUTHOR]

A natural stress response induces elevated cortisol levels in biological fluids, such as saliva. While current sensor technologies can detect cortisol in real time, their sensitivity and reliability for human subjects have not been assured. This is due to relatively low concentrations of salivary cortisol, which fluctuate throughout the day and vary significantly between individuals. To address these challenges, we present an improved electrochemical biosensor leveraging graphene's exceptional conductivity and physicochemical properties. A 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBASE-NHS)–modified commercial graphene foam (GF) electrode is presented to realize an ultra-sensitive biosensor for cortisol detection directly in human saliva. The biosensor fabrication process entails the attachment of anti-cortisol monoclonal antibodies (mAb-cort) onto a PBASE-NHS/GF electrode through noncovalent immobilization on the vertically stratified graphene foam electrode surface. This unique immobilization strategy preserves graphene's structural integrity and electrical conductivity while facilitating antibody immobilization. The binding of cortisol to immobilized mAb-cort is read out via differential pulse voltammetry using ferri/ferro redox reactions. The immunosensor demonstrates an exceptional dynamic range of 1.0 fg mL−1 to 10,000 pg mL−1 (R2 = 0.9914) with a detection limit of 0.24 fg mL−1 (n = 3) for cortisol. Furthermore, we have established the reliability of cortisol sensors in monitoring human saliva. We have also performed multiple modes of validation, one against the established enzyme-linked immunosorbent assay (ELISA) and a second by a third-party service Salimetric on 16 student volunteers exposed to different stress levels, showing excellent correlation (r = 0.9961). These findings suggest the potential for using mAb-cort/PBASE-NHS/GF-based cortisol electrodes for monitoring salivary cortisol in the general population. [ABSTRACT FROM AUTHOR]

In this study, we propose an eco-friendly method for synthesizing cerium tungstate nanoparticles using hydrothermal techniques. We used scanning, transmission electron microscopy, and X-ray diffraction to analyze the morphology of the synthesized nanoparticles. The results showed that the synthesized nanoparticles were uniform and highly crystalline, with a particle size of about 50 nm. The electrocatalytic properties of the nanoparticles were then investigated using cyclic voltammetry and electrochemical impedance spectroscopy. We further used the synthesized nanoparticles to develop an electrochemical sensor based on a carbon paste electrode that can detect hydroquinone. By optimizing the differential pulse voltammetric method, a wide linearity range of 0.4 to 45 µM and a low detection limit of 0.06 µM were obtained. The developed sensor also expressed excellent repeatability (RSD up to 3.8%) and reproducibility (RSD below 5%). Interferences had an insignificant impact on the determination of analytes, making it possible to use this method for monitoring hydroquinone concentrations in tap water. This study introduces a new approach to the chemistry of materials and the environment and demonstrates that a careful selection of components can lead to new horizons in analytical chemistry. [ABSTRACT FROM AUTHOR]

An electrochemical sensor capable of detecting glutathione (GSH) with high sensitivity and selectivity was developed based on the unique novel electroactive silver-based metal organic framework (Ag-MOF). The Ag-MOF obtained by silver nitrate and 1,3,5-benzoic acid (H3BTC) was thoroughly characterized and was modified onto the electrode via facile drop-casting method. The electrochemical response of GSH on the Ag-MOF modified electrode showed a significant reduction in the current signal because the Ag-GSH complex had stronger specific affinity than Ag-H3BTC and resulted in the collapse of the Ag-MOF. This sensor demonstrated an extensive linear dynamic range of 0.1 nM-1 µM, along with the low detection limit of 0.018 nM. Additionally, it exhibited good reproducibility, stability, and resistance to interfering compounds. The Ag-MOF modified electrode demonstrated superior performance attributed to its rapid electron transfer rate, outstanding electrochemical redox activity, and specific recognition/competitive reaction. These factors improved both sensitivity and selectivity. The high anti-interference ability allowed for the selective detection of GSH in intricate surroundings. In the real sample testing, the RSD was lower than 3.1% and the recovery was between 98.1 and 103%. This research highlights the potential of Ag-MOFs in developing electrochemical sensors and their promising applications in determining GSH for food screening and early disease diagnosis. [ABSTRACT FROM AUTHOR]

An ultrasensitive electrochemical biosensing platform has been designed by combining electrocatalysis-assisted H2S amplification with a chemical reaction-mediated electrochemical signal-boosted system for H2S detection based on Cu-Mn(OH)2 hexagonal nanorings. The signal amplification is initiated by an electrocatalysis reaction that can grasp specific H2S substrates and further highly amplify electrochemical signals. Then, the unique chemical reaction is powered by copper ion and generates a large amount of electroactive CuxS products on the electrode surface, thus achieving the multiple amplification of H2S detection. Finally, the Cu-Mn(OH)2 loaded with plenty of electroactive CuxS can be captured on the electrode for further improving the electrochemical signal thus obtaining ultra-high sensitive determination of H2S. The established electrochemical biosensing platform displays a wide analytical range of 0.1 μM to 265 μM with a low detection limit of 0.096 μM. The satisfactory selectivity allows the electrochemical sensor to distinguish H2S from other interfering substances without any complicated pretreatment, even in complex tumor cell samples. Thus, our designed electrocatalysis-assisted amplification strategy offers a powerful analysis toolkit for the early determination of H2S-related disease in clinical diagnosis. [ABSTRACT FROM AUTHOR]

The two-dimensional porphyrin-based covalent organic framework (denoted by Tph-TDC-COF) was used as the sensitive layerto build an aptamer-based electrochemical sensor for the detection of Escherichia coli (E.coli). Tph-TDC-COF produced with 5,10,15,20-tetrakis(4-aminophenyl)-21H, 23H-porphine (Tph) and [2,2′-bithiophene]-2,5′-dicarbaldehyde (TDC) as building blocks exhibited a highly conjugated structure, outstanding conductivity, large specific surface area, and strong bioaffinity towards aptamers. The adoption of Tph-TDC-COF-modified electrode resulted in improved sensing performance and increased anchoring affinity toward the E.coli-targeted aptamer. Under optimal conditions, the Tph-TDC-COF-based electrochemical aptasensor demonstrated an extremely low detection limit of 0.17 CFU mL−1 for E.coli detection within a linear range of 10 to 1 × 108 CFU mL−1, accompanied by good stability, excellent reproducibility and regeneration ability, and wide practical applications. The current electrochemical aptasensing technique has the potential to be extended to detect different foodborne bacteria using specific aptamer, therefore widening the application of COFs in biosensing and food safety fields. [ABSTRACT FROM AUTHOR]

In this paper, a MnO2 nanowire (MnO2-NW) modified carbon paper electrode (CP) was developed as a novel electrochemical sensor for the sensitive determination of tetrabromobisphenol A (TBBPA). The MnO2 nanowire was prepared by a hydrothermal synthesis method, and the morphology and structure of MnO2 were characterized using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical performance of TBBPA on MnO2-NW/CP was investigated by cyclic voltammetry, and the result confirmed that MnO2-NW/CP exhibited excellent sensitivity for the determination of TBBPA due to the high specific surface area and good electrical conductivity of the nanowire-like MnO2. Moreover, the important electrochemical factors such as pH value, incubation time and modified material proportion were systematically studied to improve the determination sensitivity. The interferences from similar structure compounds on TBBPA have also been investigated. Under the optimal conditions, MnO2-NW/CP displayed a linear range of 70~500 nM for TBBPA with a detection limit of 3.1 nM. This was superior to some electrochemical methods in reference. The work presents a novel and simple method for the determination of TBBPA. [ABSTRACT FROM AUTHOR]

Nicotine is the one of the major addictive substances; the overdose of nicotine (NIC) consumption causes increasing heart rate, blood pressure, stroke, lung cancer, and respiratory illnesses. In this study, we have developed a precise and sensitive electrochemical sensor for nicotine detection in saliva samples. It was built on a glassy carbon electrode (GCE) modified with graphene (Gr), iron (III) phthalocyanine-4,4′,4″,4′′′-tetrasulfonic acid (Fe(III)Pc), and gold nanoparticles (AuNPs/Fe(III)Pc/Gr/GCE). The AuNPs/Fe(III)Pc/Gr nanocomposite was prepared and characterized by using FE-SEM, EDX, and E-mapping techniques to confirm the composite formation as well as the even distribution of elements. Furthermore, the newly prepared AuNPs/Fe(III)Pc/Gr/GCE-nanocomposite-based sensor was used to detect the nicotine in phosphate-buffered solution (0.1 M PBS, pH 7.4). The AuNPs/Fe(III)Pc/Gr/GCE-based sensor offered a linear response against NIC from 0.5 to 27 µM with a limit of detection (LOD) of 17 nM using the amperometry (i–t curve) technique. This electrochemical sensor demonstrated astounding selectivity and sensitivity during NIC detection in the presence of common interfering molecules in 0.1 M PBS. Moreover, the effect of pH on NIC electro-oxidation was studied, which indicated that PBS with pH 7.4 was the best medium for NIC determination. Finally, the AuNPs/Fe(III)Pc/Gr/GCE sensor was used to accurately determine NIC concentration in human saliva samples, and the recovery percentages were also calculated. [ABSTRACT FROM AUTHOR]

Monitoring of anticancer drugs is an important strategy in clinical investigation. Determining the level of these drugs in chemotherapy processes provides useful information about the treatment process. The etoposide is one of the important drugs approved to lung cancer with many side effects. Therefore, monitoring of it is so important in clinical process and specially chemotherapy processes. The presence study focused on design of a new, simple, electrical-based, safe and fast response sensor to trace level monitoring of etoposide in biological fluids and pharmaceutical samples. The sensor successfully determined etoposide in nano-level concentration that is very important to investigation role of this anticancer drug in biological fluids. To this goal, the graphene nanoribbon nano-catalyst (GNR) was synthesized and characterized by MAP and SEM methods. The electrochemical catalytic activity of it was investigated by electrochemical impedance spectroscopy method. In continuous, glassy carbon electrode (GCE) modified with GNR was fabricated and ability of sensor to sensing of etoposide was investigated by differential pulse voltammetric (DPV) method. The GNR/GCE monitored etoposide in the concentration range 0.4–150 µM with detection limit 0.1 µM by DPV methods. At biological condition (pH = 7.4), the GNR/GCE was successfully used to monitoring of etoposide in urine, serum and injection samples and data confirmed with HPLC method and Statistical tests. [ABSTRACT FROM AUTHOR]

The current work aimed to fabricate a new cocaine sensor of octahedral palladium‐doped cobaltite composite (Oh‐Pd2+ : Co3O4‐C) using a simple hydrothermal protocol. As‐fabricated cocaine sensing approach was validated by various methods. Energy dispersive X‐ray analysis, X‐ray diffraction and scanning electron microscopy were recruited to characterize our charged modified composite. The electrode could sensitively detect cocaine, with a lengthy linear range (0.01 μM–900.0 μM) and a limit of detection (1.3 nM). The quantitative cocaine determination was achieved in the biological specimens using our modified electrode, the results of which displayed admirable outcomes. [ABSTRACT FROM AUTHOR]

This study addressed the use of manganese dioxide nanorods/graphene oxide nanocomposite (MnO2 NRs/GO) for modifying a glassy carbon electrode (GCE). The modified electrode (MnO2 NRs/GO/GCE) was used as an electrochemical sensor for the determination of hydroquinone (HQ) in water samples. Differential pulse voltammetry (DPV), cyclic voltammetry (CV), and chronoamperometry were used for more analysis of the HQ electrochemical behavior. Analyses revealed acceptable electrochemical functions with lower transfer resistance of electrons and greater conductivity of the MnO2 NRs/GO/GCE. The small peak-to-peak separation is an indication of a rapid electron transfer reaction. Therefore, this result is probably related to the effect of the MnO2 NRs/GO nanocomposite on the surface of GCE. In the concentration range of 0.5 μM to 300.0 μM with the detection limit as 0.012 μM, there was linear response between concentration of HQ and the current. The selectivity of the modified electrode was determined by detecting 50.0 μM of HQ in the presence of various interferent molecules. At the end, the results implied the acceptable outcome of the prepared electrode for determining HQ in the water samples. [ABSTRACT FROM AUTHOR]

6-thioguanine (6-TG) is an anticancer drug with narrow safe dose range and intense toxic reactions, so it is urgently necessary to evaluate its clinical usage. Therefore, from the point of view of human health control, the 6-TG determination in biological matrices is of great significance. The current attempt was made to produce magnetic core–shell Fe3O4@SiO2/MWCNT nanocomposite (MCFSMW) to construct a novel selective and sensitive electrochemical 6-TG sensor. The characteristics of synthesized nanocomposite were determined by X-ray Diffraction, Fourier Transform Infrared Spectrometry, Scanning Electron Microscopy and Energy-Dispersive X-ray. The sensor fabrication was based on the surface modification of screen-printed electrode (SPE) with MCFSMW (MCFSMW/SPE). The MCFSMW/SPE possessed an appropriate response and an appreciable electrooxidation behaviors toward the 6-TG detection. There was a significant enhancement in the 6-TG electro-oxidation signal on the MCFSMW/SPE surface compared to the bare SPE. The proposed protocol was explored by chronoamperometry, cyclic voltammetry, and differential pulse voltammetry (DPV). The DPV findings clarified a broad linear relationship between the 6-TG concentrations and the peak height ranged from 0.01 to 280.0 µM with a limit of detection as narrow as 1.0 nM. The practical potency of MCFSMW/SPE was confirmed by sensing of 6-TG in the biological matrices. [ABSTRACT FROM AUTHOR]

In this study, silver nanoparticles (Ag‐NPs) were synthesized using AgNO3 through a simple route using bio‐oil obtained from flash pyrolysis of Phoenix dactylifera seed powder as reducing as well as capping agent. The acquired bio‐oil was characterized by FT‐IR and GC–mass spectrometry. Besides, the main objective of this study is to construct a highly sensitive sensor to detect ornidazole (ODZ) in real samples. The sensor was elaborated by using carbon paste electrode modified with the synthesized Ag‐NPs (Ag‐NPs /CPE). The synthesized Ag‐NPs were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) and UV‐Visible (UV‐vis). The resulting sensor demonstrates a significant shift in ODZ reduction peak toward more positive potential (−0.257 V.vs Ag/AgCl) compared to the unmodified CPE (−0.561 V.vs Ag/AgCl). The ODZ peak reduction current Ipc varies linearly with ODZ concentration in the range of 8.0×10−6 to 1.0×10−3 mol L−1 with a detection limit of 9.76×10−7 mol L−1. The proposed method has been successfully used to determine ODZ in milk sample with satisfactory results. [ABSTRACT FROM AUTHOR]

The ability of corncob biochar as a modifier of carbon paste electrodes for nitrite sensing was investigated and compared to unmodified carbon paste electrodes. Nitrite standard solutions in 0.1 M phosphate buffer solution (pH 7.0) were measured using cyclic voltammetry with a potential range of 0.1 to 1 V and a scan rate of 100 mV s – 1. The corncob biochar-modified carbon paste electrode provided better performance than the unmodified electrode, with an anodic peak of 20 mg L – 1 nitrite appearing at a potential of 0.84 V, indicating nitrite oxidation. In contrast, the unmodified carbon paste electrode did not show any significant peak. To confirm that the observed peak is indeed the anodic peak of nitrite, we conducted measurements at different nitrite concentrations of 0, 20, and 50 mg L – 1. In the absence of nitrite, no significant peak was observed. However, in nitrite solutions, the anodic peak increased with higher concentrations of nitrite. Additionally, the corncob biochar-modified carbon paste electrode demonstrated good selectivity for nitrite detection, as cyclic voltammetric measurements of some interference components did not produce redox peaks in the potential range of nitrite oxidation. These findings suggest that corncob biochar has significant potential for the development of electrochemical nitrite sensors. [ABSTRACT FROM AUTHOR]

2,4-dinitrophenylhydrazine (2,4-DNPH) is a toxic organic pollutant which is highly threatening to human beings and their living environment. Therefore, it is of great significance to develop sensors for detecting 2,4-DNPH and its metabolites. To develop a two-way electrochemical sensor for the detection of 2,4-DNPH and its metabolite, Cu-containing tungstophosphate (Na16P4W30Cu4(H2O)2O112·nH2O, Cu4P4W30) was selected to study its electrocatalytic activity for the reduction of 2,4-DNPH and oxidation of its metabolite. First, the electrochemical behavior of Cu4P4W30 was investigated in solution; then, the films containing Cu4P4W30 and graphene oxide (GO) were fabricated on indium tin oxide (ITO) to form the modified ITO/PDDA/(Cu4P4W30/PDDA-GO)n electrode and the effect of the layer number on the electrocatalytic performance of the modified electrode was studied, confirming the optimal film layer number. Furthermore, the sensing performance of the modified electrode was tested, giving a linear concentration range and detection limit. Finally, the stability, repeatability, and reproducibility of the modified electrode were evaluated. The findings demonstrated that the proposed electrode acted as a two-way electrochemical sensor for the detection of 2,4-DNPH and its metabolite. [ABSTRACT FROM AUTHOR]

A molecularly imprinted electrochemical sensor (MIECS) for trace determination of taurine was developed. The sensor was constructed by electropolymerizing dopamine and o-phenylenediamine as dual monomers on the surface of amino-functionalized iron-based MOFs and graphene composite-modified electrode. The porous structure and large specific surface area of amino-functionalized iron-based MOFs not only increase the number of imprinted sites, but also facilitate the binding of molecularly imprinted films. The presence of dual monomers can increase the binding sites during the formation of imprinted films. The linear range of this sensor for taurine detection is 1.00 × 10−14–1.00 × 10−8 mol L−1 with a determination limit of 3.20 × 10−15 mol L−1. The proposed MIECS was successfully applied to quantify the amount of taurine in human serum sample with good recovery values from 97.3 to 113%. [ABSTRACT FROM AUTHOR]

Foodstuff contaminants must always be monitored and analyzed in order to address their impact on human health. Hence, efforts continue to be made to achieve sensitive and selective simple detection protocols. Accordingly, the current work aimed construct the two-dimensional (2D) bimetallic nickel-ruthenium metal organic framework nanosheets (NiRu-MOF NSs) using a simple solvothermal protocol. Structural and morphological studies and bimetallic composition analysis were fulfilled by energy dispersive X-ray, field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscope (TEM), Raman spectroscopy, N2 adsorption–desorption isotherm and thermal gravimetric analyses (TGA). As-prepared 2D bimetallic NiRu-MOF NSs could be used to modify on screen printed electrode (SPE) surface, the resultant sensor of which (NiRu-MOF/SPE) was utilized to detect sudan I in presence of bisphenol A in the real specimens. According to electrochemical responses, our sensor displayed an impressive electrocatalytic behavior towards the oxidation of sudan I, with a great sensitivity (0.0846 μA/μM) in the range from 0.01 to 460.0 μM and limit of detection of 8.0 nM with the signal to noise ratio (S/N) of 3. As-fabricated sensor could determine bisphenol A and sudan I in foodstuff samples and the results of quantitative recoveries for each compound were satisfactory. [ABSTRACT FROM AUTHOR]

A sensitive electrochemical sensor was fabricated based on Fe3O4/ZIF-4 nanoparticles (NPs) modified screen printed graphite electrode (Fe3O4/ZIF-4/SPGE) for detection of bisphenol A. Characterization of Fe3O4/ZIF-4 NPs was performed by EDX, MAP, XRD, FT-IR, FESEM, TEM and TGA. The performance of the designed electrochemical sensor was tested by voltammetric techniques. Fe3O4/ZIF-4/SPGE exhibited very acceptable electrocatalytic activities for oxidizing bisphenol A via considerable increase of the peak currents and changes in the peak potentials towards less positive potentials. Fe3O4/ZIF-4/SPGE demonstrated excellent sensing performance with the wider linear ranges (0.06–300.0 µM), lower limit of detection (LOD) (0.015 ± 0.001µM), and high sensitivity (0.1274 µA µM-1). The practical applicability has been demonstrated through the detection of bisphenol A in different real samples. [ABSTRACT FROM AUTHOR]

A facile method was proposed for the elaboration of an electrochemical sensor for heavy metal's trace detection by using square wave anodic stripping voltammetry (SWASV); this method is based on a simple anodic conversion of tin electrode into Sn/SnO2 modified electrode. Both electrochemical and physico-chemical techniques were used to confirm the modification process and better understand the electrode's behavior. Then, depending on the operating conditions, the response signal was studied and adjusted in order to obtain optimal sensor performance. When optimized, the proposed method reached a lowest detection limit (LOD) of 2.15 μg L−1 (0.0104 μM), and quantification limit (LOQ) of 5.36 μg L−1 (0.0259 μM), in linearity range between from 6.2 and 20.7 μg L−1. Additionally, after having used the elaborated electrode for ten successive measurements, the repeatability remains very high with an RSD of approximately 5.3%; furthermore, ten other species appear to have very slight effect on Pb(II) detection. Finally, for the method validation, the proposed electrode was able to sense different lead concentration integrated in a local bottled spring water by showing recovery levels ranging from 103.8 to 108.4%. [ABSTRACT FROM AUTHOR]

The abnormal levels of four DNA bases, namely guanine (G), adenine (A), thymine (T), and cytosine (C) are implicated in several cancers, metabolic diseases, and HIV/AIDS. Therefore, the accurate detection and concentration measurement of these four DNA bases is of significant interest. Furthermore, there has recently been a push towards developing chemical sensors which are more sustainable and cost-effective. Herein, we developed a graphite paste electrode which incorporated the biochar of sugarcane and methylene blue (GPE-SC-MB) in order to simultaneously detect these four DNA bases. The linear ranges obtained for the four DNA bases are 0.67–38.67 µM for G, 0.67–126.67 µM for A, and 6.67–1600 µM for T and C. The limit-of-detection (LOD) values obtained were 0.037 μM for G, 0.042 µM for A, 4.25 μM for T, and 5.33 µM for C. The electroactive surface area of the electrode as well as the diffusion coefficients for each analyte were determined. Lastly, the GPE-SC-MB was tested in real samples using human saliva with recovery values between 99.0 and 103.0%. Thus, biochar from sugarcane proved to be an effective electrode modifier material for the development of sensitive electrochemical sensors. [ABSTRACT FROM AUTHOR]

Owing to their potentially elevated catalytic activity, diverse morphology and abundant active sites, cobalt phosphides (Co 2 P, CoP etc.) have garnered important interest in modified materials for electrochemical sensors. Nevertheless, their low intrinsic conductivity still restrained and limited their electrochemical application. Herein, a solid-state gas-steamed metal-organic-framework strategy was designed to construct carbon-encapsulated cobalt phosphide nanoparticles and N doped carbon substrates (denoted as CoP/Co 2 P@NC) composites using ZIF-67 as the MOFs precursor. The resultant catalyst exhibited excellent the electrocatalytic activity for the detection of catechol (CC) and hydroquinone (HQ) due to the composites with the large surface area, high stability and enhanced conductivity. The CoP/Co 2 P@NC-modified electrode facilitated a quasi-reversible redox reaction for CC and HQ, characterized by a significant oxidation current response. Under the optimum electrochemical conditions, the CoP/Co 2 P@NC was stable, reproducible and demonstrated wide ranges (0.05–80 μM and 0.05–80 μM) and low detection limits (20 nM and 30 nM) for HQ and CC. Furthermore, the CoP/Co 2 P@NC modified electrode was successfully developed a cost-effective electrochemical environmental monitoring sensor. [Display omitted] • The CoP/Co 2 P@NC composites were fabricated by a green gas-steamed MOF approach. • The CoP/Co 2 P@NC composites sensor was firstly developed. • The outstanding performances of composites sensor was shown. [ABSTRACT FROM AUTHOR]

A well-known fungicide designated diethofencarb (DFC) is used on crops to eradicate fungal infections and increase agricultural production. However, the National Food Safety Standard has established an overall maximum residual limit of 1 mg/kg for DFC, and excessive usage of this chemical has detrimental effects on the environment in real-time. In this work, an improved electrochemical sensor based on hydrothermally synthesized CaZrO 3 is incorporated into a g-C 3 N 4 sheet and developed to quickly and accurately screen DFC, a well-known carbamate fungicide. The electrochemical sensor that was successfully designed demonstrated good conductivity, high ion diffusion parameters, a high electro-active surface area, and a quick electron transport ratio when used for DFC detection. The structure, crystalline accuracy, and purity of the as-prepared CaZrO 3 @g-C 3 N 4 were examined using various analytical and microscopic techniques. Additionally, the cyclic voltammetry technique examined the electrochemical investigations of the CaZrO 3 @g-C 3 N 4 modified glassy carbon electrode (GCE). A robust synergistic interaction between the CaZrO 3 and g-C 3 N 4 makes large surface areas and improved DFC detection possible. The fabricated sensor exhibits a wide linear range of 0.01–230.04 μM, a low detection limit of 1.8 nM, and excellent stability according to the results of the DPV technique. Remarkably, our proposed sensor has proven to be feasible for real-time analysis and can distinguish DFC-spiked various food samples with a good recovery range. [Display omitted] • Facile synthesis of CaZrO 3 @g-C 3 N 4 using sonochemical method. • Electrochemical detection of diethofencarb fungicide using CaZrO 3 @g-C 3 N 4 /GCE. • Proposed sensor exhibited LOD and wide linear ranges at CaZrO 3 @g-C 3 N 4 /GCE. • Practicality of fabricated sensor in spiked DFC in strawberry, grapes, spinach, and apple samples. [ABSTRACT FROM AUTHOR]

A novel electrochemical sensor for detection of dopamine in the presence of uric acid was constructed. [Display omitted] • Y-Cu-MOFs were synthesized by the in-situ solvothermal approach. • The characterization of the Y-Cu-MOFs revealed a relatively high surface are and porous structure. • Y-Cu-MOFs/CPE sensor was applied to simultaneously determination of DA and UA. In this work, bimetallic yttrium-copper metal–organic frameworks (Y-Cu-MOFs) are fabricated via a solvothermal strategy. The Y-Cu-MOFs were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Field emission-scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS) and elemental mapping analysis. Then a voltammetric dopamine sensor was created based on a carbon paste electrode modified with bimetallic Y-Cu-MOFs (Y-Cu-MOFs/CPE). Further, several electrochemical methods were employed to investigate DA electrochemical behavior at Y-Cu-MOFs/CPE. The modified electrode, featuring the suitable catalytic performance of Y-Cu-MOFs, led to a notable improvement in the electrochemical signal output during the electro-oxidation of DA. Under optimal conditions, the Y-Cu-MOFs/CPE sensor demonstrates superior detection capabilities, with a broad linear range to DA from 0.1 to 400.0 μM and a limit of detection (LOD) of 0.04 μM. Also, the differential pulse voltammetry method (DPV) was utilized to analyze DA in the presence of uric acid (UA). DPV results indicated that the peak-to-peak separation of DA and UA was 170 mV at the Y-Cu-MOFs/CPE. Finally, the practical feasibility analysis demonstrates a recovery of 96.3 % and 104.2 % for DA and UA in dopamine injection and urine specimens. [ABSTRACT FROM AUTHOR]

The electrochemical sensor shows great promise in the detection of trace Hg(Ⅱ), of which the performance could be significantly enhanced by the functionalized material with the merits of effective and ultrafast capture for Hg(Ⅱ). In this study, the novel metal coordination polymers (MCPs) was synthesized by the 2-thio-barbituric acid as the organic ligand to modify the electrochemical sensor to address this issue. The as-prepared material was composed of regular flakes with a polyhedral and well-defined crystal structure, the successful loading of the abundant sulfurous group (7.49 % of the total mass) endowed the Zn-TBA with the capability to efficiently uptake (97.4–99.9 %) Hg(Ⅱ) at 500 mg/L under a wider pHs as well as the high content of coexisting cations and anions, highlighted the excellent capacity, strong environmental adaptability, and selectivity. Notably, the superfast mass transfer was revealed in the adsorption kinetics test, in which the Hg(Ⅱ) content was effectively reduced from 50 mg/L to 14 μg/L within 20 s to meet the national emission standards. Based on this, Zn-TBA modified the carbon cloth (Zn-TBA/CC) and the glass carbon electrode (Zn-TBA/GCE) was prepared, thereinto, the current response of Zn-TBA/CC was approximately 60 times that of the pristine electrode. A strong positive correlation (R2=0.998) relationship could be attained across the content of 0.25–3 μM, achieving the detection limit to be 0.29 μM. The impressive performance was maintained in the complex matrices and regeneration test. In addition, Zn-TBA/CC exhibited better physical properties, charge transfer ability, and sensing properties than Zn-TBA/GCE, highlighting the advantages of CC as a flexible sensor substrate. Finally, the stable recovery (90–98.5 %) in the spiked actual surface water confirmed that the two established methods possessed a promising application potential in capturing and detecting the trace Hg(Ⅱ) with high accuracy and precision. This study extended the application of MCPs in the electrochemical sensor and provided an available analysis method to trap and determine the metal content. [Display omitted] • The novel Zn-TBA exhibited the ultra-fast and efficient capture of aquatic Hg(Ⅱ). • The anchoring and ample S endowed the material with high adaptability and efficiency. • The Zn-TBA/CC enhanced the response by 60 times of the pristine electrode. • The proposed method achieved trace Hg(Ⅱ) detection in surface water. [ABSTRACT FROM AUTHOR]

This illustrated abstract describes how to prepare lamellar structure metal Ni-MOF by simple hydrothermal method. Ni-MOF/RGO nanocomposites were prepared by proportionally mixing Ni-MOF and RGO via ultrasonication. Ni-MOF/RGO were used to modify onto GCE and detect EP and FA in actual human serum and urine samples. [Display omitted] • A facile hydrothermal method is employed to synthesize Ni-MOF as electrode modifier. • Ni-MOF/RGO/GCE is highly sensitive for simultaneous determination of EP and FA. • Ni-MOF/RGO/GCE exhibits a low LOD and excellent selectivity, reproducibility and stability. • The sensor is used for the simultaneous detection of EP and FA in biological fluids samples. Epinephrine (EP) and Folic Acid (FA) coexist in human body fluids, and monitoring their levels is important for human health. The detection of these two biomarkers can provide early data support for preventing or treating related diseases, which helps to improve the effectiveness of diagnosing, treating, and preventing a variety of health issues. An efficient and convenient electrochemical sensor for simultaneous detect of EP and FA was developed, utilizing reduced Graphene Oxide (RGO) and Nickel-Metal Organic Framework (Ni-MOF) nanocomposite to modify glassy carbon electrodes (GCE). The electrocatalytic performance of Ni-MOF/RGO/GCE for the EP and FA was investigated in detail. With detection limits for EP and FA were 0.018 μM and 0.016 μM, respectively, the wide linear range was 0.05–150 μM and 0.01–200 μM. The findings indicate that the developed Ni-MOF/RGO/GCE sensing platform offers high sensitivity, rapid response time, and robust anti-interference capabilities. This composite material has been effectively utilized for the detection of EP and FA in both human urine and serum samples, yielding impressive recovery rates. Prepared sensor holds promise for healthcare monitoring applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two-dimensional leaf-like ZIF-L (Zn) nanocomposite was synthesized. • This modified electrode was used for determination of uric acid, dopamine, and theophylline. • It was used for real sample analysis. The two-dimensional (2D) leaf-like zeolitic imidazolate framework-L (Zn) (ZIF-L (Zn)) was synthesized using a simple method in this study. The ZIF-L (Zn) was characterized using various techniques, such as FE-SEM, XRD, FT-IR, elemental mapping and EDX. The ZIF-L (Zn) was utilized to modify the surface of screen-printed graphite electrode (ZIF-L (Zn)/SPGE) to detect uric acid (UA). The sensor exhibited electrocatalytic behavior for uric acid in phosphate buffer solutions (PBS, 0.1 M), with a linear dependence between the current response and uric acid concentration in the dynamic range from 0.1 μM to 900.0 μM, a low limit of detection (LOD) of 0.04 μM, and good sensitivity of 0.0393 μA/μM under optimized experimental conditions. The ZIF-L (Zn)/SPGE sensor was successfully applied for uric acid determination in the presence of dopamine (DA) and theophylline (Thp) without any interference. The proposed electrode exhibits well-separated oxidation peaks at potentials of 139, 260 and 900 mV for dopamine, uric acid, and theophylline, respectively. In addition, the practical application of the fabricated sensor was demonstrated by detecting dopamine, uric acid, and theophylline in real samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • The discussion highlighted voltammetric electrochemical methods for detecting HMIs. • Recent advances in electrochemical sensing for HMIs detection using nanomaterials. • Recent advances in electrochemical sensing for HMIs detection using aptamers. • Emerging insights and future prospects for voltammetric techniques in HMIs detection were discussed. Naturally occurring heavy metals (HMs) present a serious risk to human health and the environment because of their toxicity, persistence, and tendency to bioaccumulate. Their presence in air, water, soil, and food can lead to a multitude of adverse effects, from acute poisoning to chronic health problems. The rapid expansion of industrialization and technology has increased HMs contamination from industrial emissions, mining, agriculture, urbanization, and e-waste, posing serious risks to ecosystems and public health. To tackle this increasing challenge, it is essential to develop highly robust, sensitive, and selective electrochemical detection methods for the rapid identification of heavy metal ions (HMIs) contaminants. This review investigates a variety of electrochemical sensors and biosensors utilizing voltammetric techniques for HMIs detection. It covers voltammetric methods such as cyclic voltammetry (CV), square wave voltammetry (SWV), differential-pulse voltammetry (DPV), normal pulse voltammetry (NPV), staircase voltammetry (SV), linear sweep voltammetry (LSV), hydrodynamic voltammetry (HV), anodic stripping voltammetry (ASV), cathodic stripping voltammetry (CSV), and adsorptive stripping voltammetry (AdSV). The review also emphasizes recent advancements in the electrochemical detection of HMIs through various sensor and biosensor platforms, including different nanomaterials and DNA aptamers. These innovations have potential applications in environmental monitoring, food and water safety, industrial waste management, and public health protection, making them vital tools for safeguarding human health and the environment from HMIs contamination. [ABSTRACT FROM AUTHOR]

In the context of this experimental study, new palladium and ruthenium complexes based on a symmetric ligand, named 2E-Peaemp ((3 E ,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 (NO 2 -; trace) without any interference from other ions substances as acetate (CH 3 COO-), borate (BO 3 −3), phosphate (PO 4 −3), dihydrogen (2 H+), sulfate (SO 4 −2), sodium (Na+), hydroxide (OH-), potasium (K+), chloride (Cl-), magnesium (I) (Mg+), nitrate (NO 3 -), calcium (Ca2+), carbonate (CO 3 −2). [Display omitted] • Pd (II) and Ru (III) complexes and their hybrid materials with MWCNT were synthesized and characterized. • Three modified electrodes were developed and tested to separate and simultaneous nitrite and tartrazine detection. • A selective and sensitive sensor (MEC/CG-MWCNT-Pd-2E-Peaemp) was elaborated and validated in real samples. • Low concentrations of NO 2 - in natural environment without any interference from other substances have been determined. [ABSTRACT FROM AUTHOR]

Hemeprotein detection has motivated extensive research on the direct reaction of a heme molecule and a redox dye. The present study used methylene blue as both donor and acceptor for a redox reaction. First, the solid phases of methylene blue (MB) and graphene (GP) formed a π-π interaction bond at the aromatic rings. The conductivity of GP was better than that of carbon in a carbon electrode (CE). Then, the working CE was modified using strong adsorption of MB/GP on the electrode surface. The surface of the electrode was investigated using a modified and an unmodified electrode. The electrode's properties were studied using voltammograms of redox couple K3[Fe(CN)6]3−/4−. Its reaction was used to find the active area of the modified electrode, which was 1.76 times bigger than that of the unmodified electrode. The surface coverage values of the modified and unmodified electrodes were 8.17 × 10−6 and 1.53 × 10−5 mol/cm2, respectively. This research also studied the application of hemeprotein detection. Hemoglobin (Hb), myoglobin (Mb), and cytochrome c (Cyt. C) were studied by the reaction of Fe (III/II) at the heme-redox center. The electrocatalytic reaction between MB/GP and hemeproteins produced an anodic peak at 0.35 V for Hb, Mb, and Cyt. C. This nanohybrid film enhanced electron transfer between protein molecules and the modified carbon electrode. The amperometric measurements show that the limit of detection was 0.2 µM, 0.3 µM, and 0.1 µM for Hb, Mb, and Cyt. C, respectively. The measurement spanned a linear range of 0.2 µM to 5 µM, 0.3 µM to 5 µM, and 0.1 µM to 0.7 µM for Hb, Mb, and Cyt. C, respectively. Hb showed the lowest sensitivity compared with Mb and Cyt. C due to the role of steric hindrance in the hemeprotein specificity structure. This study offers a simple and efficient fabrication platform for electrochemical sensors for hemeproteins. When compared to other complex immobilization processes, the fabrication method for this sensor has many benefits, including no need for special chemicals and easy preparation and electrode modification—both of which are crucial for the development of electrochemical sensing devices. [ABSTRACT FROM AUTHOR]

In this work, ZIF-8@ZIF-67 was prepared and pyrolyzed to obtain Co nanoparticles-embedded N-doped carbon nanotube hollow polyhedron (Co@NCNHP). Then, single-walled carbon nanohorns (SWCNHs) were mixed with Co@NCNHP to obtain the SWCNHs-Co@NCNHP composite. The morphological structure of the prepared material was characterized by scanning electron microscopy, and the as-prepared SWCNHs-Co@NCNHP was modified on the surface of glassy carbon electrode (GCE). The modified electrode was used as electrochemical sensor for analysis of luteolin. Because of the excellent synergistic effects between SWCNHs and Co@NCNHP, the sensor based on SWCNHs-Co@NCNHP/GCE could be used to detect luteolin with the detection range from 0.1 to 4.0 μM and the low limit of detection of 10.0 nM (S/N = 3). Besides, the fabricated sensor showed favorable selectivity and stability, and was used in the analysis of luteolin in Duyiwei capsules with satisfactory results. [ABSTRACT FROM AUTHOR]

An electrochemical sensor for the pesticide Pirimicarb (PMC) has been developed. A screen-printed electrode (SPCE) was used and modified with the conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) and gold nanoparticles (AuNPs) to enhance electrochemical proprieties. Electrode characterizations were performed using scattering electron microscopy (SEM) and cyclic voltammetry (CV). With the SPCE/PEDOT:PSS/AuNPs modified electrode, a new peak at 1.0 V appeared in the presence of PMC related to the PMC oxidation. To elucidate the mechanism of PMC oxidation, Gas Chromatography-Mass Spectrometry (GC-MS), where two major peaks were identified, evidencing that the device can both detect and degrade PMC by an electro-oxidation process. Exploring this peak signal, it was possible the sensor development, performing detection from 93.81–750 µmol L−1, limits of quantification (LOQ) and detection (LOD) of 93.91 µmol L−1 and 28.34 µmol L−1, respectively. Thus, it was possible to study and optimization of PMC degradation, moreover, to perform detection at low concentrations and with good selectivity against different interferents using a low-cost printed electrode based on graphite modified with conductive polymer and AuNPs. [ABSTRACT FROM AUTHOR]