Differential Pulse Voltammetry Research Articles

DETAILED ELECTROCHEMICAL BEHAVIOR INVESTIGATION AND DETERMINATION OF ANTIPSYCHOTIC DRUG PALIPERIDONE ON A GLASSY CARBON ELECTRODE

Objective: A sensitive and cost-effective electrochemical method was developed on a bare glassy carbon electrode (GCE) for the determination of paliperidone (PAL), an antipsychotic drug used in the primary schizophrenia treatment affecting the whole world. Material and Method: The oxidation studies carried out in pH 8 phosphate buffer solution (PBS) by cyclic voltammetry (CV) showed that the oxidation reaction of PAL is a process including the same number of electrons and protons. The electrochemical detection of PAL was carried out by differential pulse voltammetry (DPV). Result and Discussion: The linearity range was between 1 µM and 100 µM. The limit of detection (LOD) and quantification (LOQ) values were calculated as 2.41x10-7 M and 8.033x10-7 M, respectively. The applicability of the developed method was confirmed by using it on synthetic human serum. The relative standard deviation (RSD) values were less than 2%. The selectivity of the analysis was demonstrated over against interfering substances such as ascorbic acid, KNO3, MgCl2, paracetamol, dopamine, Na2SO4, and uric acid with recovery% and RSD% values in the range 98.32%-101.56% and 0.15%-1.99%, respectively. The proposed method provided high sensitivity for PAL and is the first reported method for the electroanalysis of PAL.

Unveiling interference‐free acridine‐calix[4]arene‐based fluorescence paper and electrochemical sensor for cyanazine from agricultural produces

The construction of fluorescence sensor L1 for cyanazine (CNZ) by using calix[4]arene scaffold allied with 9‐Aminoacridine moiety has been reported. The recognized triazine herbicide CNZ decreased the fluorescence intensity of L1 by exhibiting “turn‐off” phenomenon having detection limit to be 7.79 µM obtained from emission study. The quenching response of L1: CNZ was observed between the range of 5 – 105 µM possessing binding constant calculated to be 9.201 × 106 M‐1. The spiking experiment of CNZ into L1 has also been performed to evaluate potency of L1 using vegetables and cereals. Also, a paper‐based device has been prepared in order to implement this strategy for on‐spot monitoring of CNZ. The L1:CNZ binding has been confirmed by conducting electrochemical studies like cyclic voltammetry, differential pulse voltammetry, 1H NMR, FT – IR, MALDI‐ TOF, PXRD investigation and computational analysis.

On-Site Electrochemical Sensor for Carbamazepine Monitoring in Aquatic Environments

Abstract This work analyzes the detection of carbamazepine (CBZ), a commonly used pharmaceutical that exhibits extended persistence in aquatic habitats, by the application of advanced sensor technologies. Owing to its chemical stability, CBZ is resistant to natural degradation, posing significant ecological risks in aquatic environments. Conventional techniques for CBZ detection, such as high-performance liquid chromatography and spectrophotometry, require intricate laboratory configurations and significant sample preparation, restricting their use for fast in situ monitoring. To tackle these issues, we created a portable electrochemical sensor using screen-printed electrodes on a flexible polyester-based substrate. Under optimized conditions, the sensor demonstrated high sensitivity in a linear detection range from 1 to 20 µM with a detection limit of 0.8 M by differential pulse voltammetry technique. Recovery range was found to be 93% to 107%, which further confirmed reliability, showing consistency in CBZ detection across varied concentration levels in wastewater. Preliminary results on continuous measurements have been carried out, demonstrating a promising application for prolonged analysis in real-settings.

A bio-nano-engineered platform fabricated from cerium oxide-carbon nanoparticles stabilized with chitosan for label-free sensing of a lung cancer biomarker.

Herein, we report a label-free cancer biosensor designed for carcinoembryonic antigen (CEA) detection using a nanohybrid comprising CeO2 nanoparticles, carbon nanoparticles (CNPs), and chitosan (Ch). CeO2 nanoparticles were prepared using a simple green synthesis process. A thin film of the CeO2-CNPs-Ch nanohybrid was formed on indium tin oxide (ITO)-coated glass plates that endowed a high surface area, excellent stability, and good adsorption for the efficient loading of CEA antibodies. Quantitative and selective determination of CEA antigen was achieved by immobilizing monoclonal CEA antibodies (anti-CEA) on the CeO2-CNPs-Ch/ITO platform. The electrochemical response of the anti-CEA/CeO2-CNPs-Ch/ITO immunoelectrode was evaluated in a label-free immunoassay format using differential pulse voltammetry (DPV). The response studies of immunoelectrodes indicated wider linearity with respect to the CEA concentration in the range of 0.05-100 ng mL-1. The electrochemical cancer biosensor exhibited a higher sensitivity of 22.40 μA cm-2 per decade change in concentration along with storage stability for up to 35 days. The limit of detection (LOD) was 0.037 ng mL-1. Furthermore, this cancer biosensor exhibited good specificity and reproducibility. Thus, the proposed CeO2-CNPs-Ch nanocomposite-based platform provides an efficient method for the analysis of other antigen-antibody interactions and biomolecule detection. The efficacy of the anti-CEA/CeO2-CNPs-Ch/ITO immunoelectrode was further examined by measuring CEA levels in human serum.

An Electrochemical Sensor for Detection of Lead (II) Ions Using Biochar of Spent Coffee Grounds Modified by TiO2 Nanoparticles

Toxic heavy metal ions, such as lead ions, significantly threaten human health and the environment. This work introduces a novel method for the simple and sensitive detection of lead ions based on biochar-loaded titanium dioxide nanoparticles (BC@TiO2NPs) nanocomposites. Eco-friendly biochar samples were prepared from spent coffee grounds (500 °C, 1 h) that were chemically activated with TiO2 nanoparticles (150 °C, 24 h) to improve their conductivity. Structural characterizations showed that BC@TiO2NPs have a porous structure. The BC@TiO2NPs material was evaluated for lead ion determination by assembling glassy carbon electrodes. Under optimal conditions, the sensor was immersed in a solution containing the analyte (0.1 M NaAc-HAc buffer, pH = 4.5) for the detection of lead ions via differential pulse voltammetry. A linear dynamic range from 1 pM to 10 μMwas achieved, with a detection limit of 0.6268 pM. Additionally, the analyte was determined in tap water samples, and a satisfactory recovery rate was achieved.

Development of novel hybrid hydroxyapatite-based sensors for the ultrasensitive detection of L-tryptophan and L-tyrosine

A novel sensor using gold (Au) doped citrate-hydroxyapatite nanoparticles at different molar ratios wCitHAP-Au (w = 0.2, 0.4, 0.8) was developed. Citrate groups on the HAP nanoparticles surface makes it possible to carry out directly and homogeneously the “one-pot” deposition of the 0.5 % AuNPs from an aqueous solution. wCitHAP-0.5Au modified glassy carbon electrodes (GCE) are used in fundamental studies of the electron transfer, and in the construction of sensor devices for the determination of L-Tryptophane (TTP) and L-Tyrosine (TYR). Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) reveal the excellent electrocatalytic activity for oxidation and determination of TTP and TYR into phosphate buffer solution at pH 7 of the 0.2CitHAP-0.5Au/GCE electrode. Linear response ranges under optimal conditions were found to be 3.33 nM to 66.6 μM for TTP and 6 nM to 66.6 μM with detection limit of 3.33 nM and 6 nM, respectively. The fabricated sensor shows suitable sensitivity, stability, and can successfully applied for real samples determination.Additionally, Hirshfeld Surface (HS) analysis was conducted to gain deeper insights into the molecular properties, intermolecular interactions, and surface characteristics of the compounds studied. The HS analysis confirmed the presence of intermolecular interactions that stabilize the gold nanoparticles within the hydroxyapatite-citrate matrix, ensuring their uniform distribution and preventing aggregation.

Green electrochemical sensor for selective determination of anticancer drug Ribociclib based on banana peel activated carbon/CuCoFe-MOF/CoFe2O4 modified carbon paste electrode in pharmaceutical and biological samples

The development of efficient and eco-friendly sensing platforms for the sensitive detection of anticancer drugs like Ribociclib (RIB) is essential for advancing therapeutic monitoring and ensuring patient safety. In this study, we introduce a novel electrochemical sensor that utilizes a unique CuCoFe-MOF/CoFe2O4/banana peel activated carbon (BPAC) composite-modified carbon paste electrode (CPE) for the sensitive quantification of RIB. This composite material, which has not been previously reported in the literature, offers enhanced electrocatalytic activity, attributed to its increased surface area and superior conductivity. Various techniques, including FT-IR, XRD, SEM-EDX, and BET analysis, were used to confirm the structural and morphological properties of the synthesized composite. Differential pulse voltammetry (DPV) results showed a broad linear range of 0.2–9.7 μM and a remarkably low limit of detection (LOD) of 0.025 μM, demonstrating its high sensitivity. The sensor’s performance was further validated in pharmaceutical formulations and biological samples, achieving recoveries between 98.6 % and 101.8 % with an RSD below 2.0 %. Additionally, the method was evaluated using the Green Analytical Procedure Index (GAPI), Analytical Greenness (AGREE), and Blue Applicability Grade Index (BAGI) tools, confirming that it is both green and highly applicable. This work presents a significant advancement in the field of electrochemical sensing for RIB detection, offering a novel, sustainable, and practical solution for real-world applications.

Metal organic framework modified with carbon nanotube as an electrochemical sensor: Fabrication, excellent stability and sensitive detection of dopamine

Dopamine (DA) is a very important drug, however, excessive use can lead to DA becoming a micropollutant in water environments, which is an unfortunate consequence. The accurate determination of dopamine content is of great significance and has also attracted high attention from people. In this work, an electrochemical sensor (MOFCN) based on carbon nanotubes (CNTs) modified copper-based metal–organic framework (Cu-MOF) was developed using the hydrothermal method for sensitive detection of dopamine. The Cu-MOF, which are surrounded by CNTs, provide a favorable surface for the full utilization of the excellent conductivity property of carbon nanotube. The surface area of MOFCN is bigger than that of original Cu-MOF. The electrochemical sensing functions of the prepared MOFCN were evaluated by cyclic voltammogram (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) techniques. Under optimal conditions, there was a good linear relationship between peak current and DA concentration in the range of 0.5 to 100 µM with a detection limit (LOD) as low as 0.13 µM. The current modified MOFCN sensor was employed to quantify trace DA concentrations in actual water sample, reaching satisfactory recovery rates ranging from 97.5 % to 105 %. The interference effect on the determination of DA showed the excellent selectivity of MOFCN using the DPV technique. A comprehensive investigation was undertaken into the kinetics and underlying mechanisms of the electrochemical reaction. The transfer of electrons and hydrogen ions facilitates the transformation of DA into dopaminoquinones (DQ), a process that is accelerated by the augmented availability of active sites in the designed sensor. The present study proposes a method for the precise and efficient analysis, which proves that the proposed sensor is highly effective for detecting DA in Environmental water samples.

Highly sensitive determination of perfluorooctanoic acid in food and river samples with an electrochemical platform based on MIP and modified MWCNTs

Perfluorooctanoic acid (PFOA), one of the emerging persistent organic pollutants, has received great concern due to high resistance to degradation and potential health risks. Numerous reports have revealed its presence in environment (soil, water, air), multiple foods and human blood with certain levels. In this study, a selective electrochemical molecularly imprinted sensor (MIP/CMC-MWCNTs@GCE) based on a template molecule of PFOA and a functional monomer of methacrylic acid (MAA) was developed via electro-polymerization on the surface of a glassy carbon electrode modified with carboxymethyl cellulose (CMC) and multiwalled carbon nanotubes (MWCNTs) for PFOA detection. The composite electrode was characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to investigate its microstructure and surface groups. Cyclic voltammetry (CV) results and electrochemical impedance spectroscopy (EIS) also showed its excellent electrochemical performance. After optimizing the experimental conditions by differential pulse voltammetry (DPV), the obtained sensor quantified PFOA in a wide range of 0.1 to 2000 ng mL−1 with a low detection limit (LOD) of 0.1287 ng mL−1. Finally, this rapid sensing method has been successfully applied in chicken, peach, tomato and river samples with a recovery rate of 92.00–113.19 %. These results present that the composite sensor has good selectivity, stability and high sensitivity for PFOA determination, which may be a promising alternative for on-site and real-time monitoring in complex samples.

Ultrasensitive electrochemical detection of miDNA-21 in human serum based on synergistic signal amplification by conducting polymers and bimetallic nanoparticles

MicroRNA-21 (miRNA-21) is a class of small non-coding RNAs that play a crucial role in the regulation of post-transcriptional gene expression. By leveraging the principle of base complementary pairing, the detection of miRNA-21 can be achieved through its analogue, MicroDNA-21 (miDNA-21), which possesses an identical sequence. Utilizing screen-printed carbon electrodes (SPCE), a conducting polymer (polypyrrole, Ppy), and metal nanocomposites (gold-platinum nanoparticles, Au@Pt NPs) were sequentially electrodeposited to create an electrochemical biosensor for the detection of miDNA-21. This biosensor employed ferrocyanide/ferricyanide (Fe(CN)63−/4−) as the electrochemical signaling probe, and its structure was elucidated via field emission scanning electron microscopy (FESEM) and Energy Dispersive Spectrometer (EDS). Quantitative detection was facilitated through differential pulse voltammetry (DPV), yielding a concentration range and linear fitting equation of 10.00–7.00 × 10.00−14 mol/L: ΔI = 0.5143 lgc + 9.191, R2 = 0.9986. The limit of detection (LOD) was determined to be 2.90 × 10−15 mol/L, with a sensitivity of 9.42 μA/μmol/L·cm2. Subsequent performance assessments confirmed the sensor’s excellent selectivity, reproducibility, and stability. Evaluation using the standard addition method, with normal human serum as the matrix, yielded recoveries ranging from 98.97 % to 102.70 %, and relative standard deviation (RSD) values below 1.00 %. These results demonstrate the method’s viability for practical application in detecting miRNA in human serum.

Investigation of the modification of gold electrodes by electrochemical molecularly imprinted polymers as a selective layer for the trace level electroanalysis of PAH

Electrochemical molecularly imprinted polymers (e-MIPs) were grafted for the first time as a thin layer to the surface of a gold electrode to perform trace level electroanalysis of benzo(a)pyrene (BaP). This was achieved by controlled/living radical photopolymerization of a redox tracer monomer (ferrocenylmethyl methacrylate, FcMMA) with ethylene glycol dimethacrylate in the presence of benzo(a)pyrene as the template molecule. For that purpose, a novel photoiniferter-derived SAM was first deposited on the gold surface. The SAM formation was monitored by cyclic voltammetry and electrochemical impedance spectroscopy. Then, the “grafting from” of the e-MIP was achieved upon photoirradiation during a controlled time. Differential pulse voltammetry was used to quantify BaP in aqueous solution by following the modification of the signal of FcMMA. A limit of detection of 0.19 nM in water and a linear range of 0.66 nM to 4.30 nM, were determined, thus validating the enhancement of sensitivity induced by the close contact between the e-MIP and the electrode, and the improved transfer electron.

Electrochemical paper-based sensor based on molecular imprinted polymer and nitrogen-doped graphene for tetracycline determination

In this work, an electrochemical paper-based analytical device (ePAD) based on molecular-imprinted polymer (MIP) and nitrogen-doped graphene (NG) was developed for sensitive electrochemical detection of tetracycline in wastewater. The NG was in-situ synthesized on the paper-based screen-printed carbon electrode (pSPCE) by potentiostatic method to improve the conductivity of the sensor. Subsequently, the MIP were electropolymerized on NG using o-phenylenediamine (oPD) as a functional monomer and tetracycline (TC) as template molecule by cyclic voltammetry (CV) to deliver the specific recognition of TC. The electrode modification process was highly controllable, and the detection efficiency was improved. The electrochemical properties of MIP/NG/ePAD were evaluated by CV, differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the fabricated ePAD sensor showed a good linear relationship with TC concentration ranging from 5 × 10−9 to 1 × 10−5 mol/L with a correlation coefficient (R2) of 0.995 and a detection limit of 3.29 × 10−9 mol/L. The ePAD sensor was successfully applied to TC detection in real water samples with satisfied recoveries from 94.0 % to 106.9 %. The low-cost, portable, high specificity, and reliable ePAD sensor proposed here has promising potential for application in point-of-care testing (POCT) in environmental monitoring.

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.

An ultra-sensitive electrochemical sensing platform based on t-dust poly-aniline for the rapid detection of the nitrite residues in real sample

ABSTRACT A Graphite carbon electrode/TdustPolyaniline-15 nanocomposite(GCE/TdPA-15 nanocomposite) prepared by the facile synthesis method and applied for nitrite sensor. Several characterization techniques were carried out for TdPA-15 nanocomposite material. Notably, the electro catalytic properties of GCE/TdPA-15 nanocomposite towards the nitrite sensing were determined utilizing Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV). The GCE/TdPA-15 nanocomposite can detect nitrite concentrations from 0.875 μM to 85.75 μM, with a detection limit of 0.781 μM and a sensitivity of 4.7514 μA mM-¹ cm-². Additionally, the GCE/TdPA-15 nanocomposite shows great potential for real-time applications.

A non-enzymatic electrochemical sensor based on zinc oxide/reduced graphene oxide (ZnO/rGO) nanocomposite for effective detection of urea

Monitoring urea levels is essential for detecting water and soil pollution and diagnosing urea cycle disorder-related diseases. The present study addresses the need for an efficient, accurate, and cost-effective detection method by developing an electrochemical sensor using ZnO/rGO nanocomposites. The sensor’s performance is evaluated through cyclic voltammetry, differential pulse voltammetry, and amperometry, with different weight ratios of ZnO and rGO (3:1, 1:1, and 1:3). The results show that the ZnO/rGO (1:1) nanocomposite modified electrode exhibits remarkable sensitivity (850.15 μA-1 mM−1 cm−2), a low limit of detection (0.07 μM), excellent selectivity, and long-term stability for urea detection. Developed sensor leverages the advantages of electrochemical sensing, including simplicity, rapid response, high sensitivity, and good selectivity, making it a promising solution for environmental monitoring and medical diagnostics.

Development of a green-synthesized molecularly imprinted polymer-based electrochemical nanosensor for the determination of N-nitrosodimethylamine (NDMA) in serum and tap water.

N-nitrosodimethylamine (NDMA) was determined using a molecularly imprinted polymer (MIP)-based electrochemical sensor.Green-synthesized silver nanoparticles were functionalized with cysteamine to enhance their integration into the electrode surface, which was used to modify a glassy carbon electrode (GCE). Furthermore, a MIP-based electrochemical sensor was constructed via electropolymerization of 3-aminophenyl boronic acid (3-APBA) as a conjugated functional monomer in the presence of lithium perchlorate (LiClO4) solution as a dopant, chitosan as a carrier natural polymer, and NDMA as a template/target molecule. The polymer film was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The analytical performance of the silver nanomaterial-based MIP-based electrochemical (AgNPs@Chitosan/3-APBA@MIP-GCE) sensor was evaluated under optimized conditions. The linear range of NDMA was 1.0 × 10-13-1.0 × 10-12M (0.1-1.0pM), with a limit of detection (LOD) of 3.63 × 10-15M (3.63 fM) using differential pulse voltammetry (DPV). Method validation figured out that the developed MIP-based electrochemical nanosensor exhibited excellent selectivity, accuracy, and precision, which was shown by the analysis of synthetic serum samples and tap water. The LOD and LOQ in serum samples were 17.8 fM and 59.5 fM,respectively,which were in agreement with the developed method. Good recovery results confirm the successful application of the method in serum and tap water samples. The selectivity of the developed AgNPs@Chitosan/3-APBA@MIP-GCE sensor for NDMA was demonstrated in the presence of NDEA, sartans (valsartan, losartan, irbesartan, candesartan, telmisartan), and potential interferents that arepossibly present in biological fluids (dopamine, ascorbic acid, uric acid) besides ionic species (sodium, chloride, potassium, nitrate, magnesium, sulfate) and common analgesic paracetamol.

Electrochemical Biosensor for the Assessment of Cell Viability Using Methylene Blue. Application to the Detection of Ciguatoxins in Fish from the Canary Islands.

Cell-based biosensors (CBBs) for the detection of marine neurotoxins such as ciguatoxins (CTXs) are of high interest due to the composite toxicological response they can provide and the low limits of quantification (LOQs) they can achieve with the use of sensitive neural cells. However, the development and validation of CBBs are challenging due to the use of living material and the need for appropriate signal transduction strategies. In this work, Neuro-2a cells have been immobilized on thin-film gold electrodes, and their viability after exposure to CTX1B has been evaluated with light optical microscopy as well as cyclic voltammetry (CV) and differential pulse voltammetry (DPV) using methylene blue (MB) as a redox indicator. An LOQ of 0.93 pg CTX1B/mL has been obtained. The CBB has been applied to the analysis of fish samples from the Canary Islands, one of them implicated in a ciguatera poisoning (CP) outbreak, and results have been compared with those obtained with a conventional cell-based assay (CBA), showing a very good agreement. The combination of the benefits of cells with those provided by biosensor platforms in terms of ease of use, miniaturization, automatization, and portability could result in the ideal analytical tool for CP management. Additionally, this is the first time MB is used as a cell viability indicator in a CBB, providing a new versatile approach for multiple applications.

Eco-friendly bupropion detection sensor with co-formulated dextromethorphan in AUVELITY tablet and spiked plasma

Molecularly Imprinted Polymers (MIPs) are synthetic materials designed to selectively recognize and bind to specific target molecules. The process of determining Bupropion (BUP) using MIPs involves preparing the MIP, extracting the target molecule, and conducting subsequent analysis. A bio-inspired MIP-based electrochemical sensor was developed to detect BUP, utilizing the specific binding of MIPs to Bupropion molecules, enabling precise and sensitive detection. The combination of molecular imprinting and electrochemistry in this approach allows for the development of a highly reliable and effective sensor specifically designed for BUP detection. In this method, copolymerization conditions were carefully optimized to ensure selectivity and sensitivity in detecting BUP. Different monomers, including o-phenylenediamine, 4-aminophenol, L-dopa, and 1,4-phenylenediamine, were explored, with the best interaction observed for L-dopa and 1,4-phenylenediamine. Consequently, their copolymer was implemented to create selective MIPs through a straightforward electropolymerization process on a disposable pencil graphite electrode (PGE) substrate for BUP detection. The functionality of the copolymer of L-dopa and 1,4-phenylenediamine as an electroactive copolymer in preparing electro-polymerized MIP films was investigated for the first time. This was demonstrated by constructing a novel electrochemical sensor for the selective recognition of BUP in different matrices. The interactions between L-dopa and 1,4-phenylenediamine, used as functional monomers, and the template were studied experimentally using UV spectroscopy. BUP was used as the template, and the copolymer was electrografted onto PGE. The constructed sensor was characterized using cyclic voltammetry (CV), and BUP binding to the MIP cavities was measured indirectly with differential pulse voltammetry (DPV) using a ferrocyanide/ferricyanide redox probe. A linear and repeatable response was displayed by the sensor across a range of 1.0 × 10⁻13 M to 1.0 × 10⁻11 M of BUP, with a limit of detection of 3.18 × 10⁻14 M. The sensor demonstrated robust selectivity for BUP over interfering drugs, such as dextromethorphan, in pharmaceutical dosage forms and spiked human plasma. The environmental impact of the proposed approach was evaluated using green analytical chemistry principles, including the Green Analytical Procedure Index (GAPI) and the Analytical GREEnness (AGREE) metric.

Synthesis of CoFe2O4@C based on Fe/Co-BTC for efficient detection, determination and degradation of nitenpyram residue: An electrochemical study, condition optimization and mechanism

As a widely-used neonicotinoid insecticide, nitenpyram is widely used in agricultural production due to its high efficiency, low toxicity and broad-spectrum insecticidal properties. However, its residue poses a potential threat to the environment and ecosystem. In this study, a new material with a core-shell structure, namely CoFe2O4@C, prepared based on Fe/Co-BTC was successfully developed for the efficient detection and degradation of nitenpyram. CoFe2O4@C exhibited excellent detection performance in the concentration range of 10−4 to 10−12 mol/L by differential pulse voltammetry (DPV) with high sensitivity (LOD = 845 fM) and good linearity (R2 = 0.9952). CoFe2O4@C also demonstrated high recoveries in real sample analyses, validating its reliability for in situ detection. In addition, it was found that CoFe2O4@C was able to efficiently promote the degradation of nitenpyram in the electro-Fenton system at a concentration of 10 mg/L under optimized conditions in only 20 min. In conclusion, CoFe2O4@C excelled in the detection of nitenpyram with its stability, reproducibility, and immunity to interference, and also demonstrated efficient performance in the electro-Fenton degradation process. Relative mechanism and pathway of CoFe2O4@C for the detection and degradation of nitenpyram have been investigated. These results not only provide a new technology for the environmental monitoring of nitenpyram, but also contribute an effective technological tool in the field of pollution control.

Development of a magnetic α-Fe2O3/Fe3O4 heterogeneous nanorod-based electrochemical biosensing platform for HPV16 E7 oncoprotein detection

The prevention, diagnosis and treatment of cancer have always been the focus of medical research. In this study, a label-free, rapid, simple, sensitive, and specific method for the detection of HPV16 E7 oncoprotein was developed. The electrochemical biosensor platform was constructed by magnetic self-assembly of α-Fe2O3/Fe3O4@Au nanocomposites onto the surface of magnetic glass carbon electrode (MGCE), and the nanocomposite was connected to aptamer through AuS bond to construct a probe to capture HPV16 E7. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were applied to verify the performance of the constructed biosensor. The condition optimization and performance analysis were carried out by differential pulse voltammetry (DPV). Under optimal conditions, the biosensor exhibited a strong linearity between current value and the logarithm of HPV16 E7 oncoprotein concentration in the range of 10 pg/mL – 0.1 μg/mL, with a limit of detection (LOD) of 159 fg/mL and a limit of quantification (LOQ) of 530 fg/mL, and it also revealed excellent reproducibility, long-term stability, and anti-interference ability. In a word, the biosensor would contribute to the early diagnosis of oncoprotein HPV16 E7 and had promising application prospects.