Synthesis of a dual-functional terbium doped copper oxide nanoflowers for high-efficiently electrochemical sensing of ofloxacin, pefloxacin and gatifloxacin

Electrochemical DNA-nano biosensor for the detection of Goserelin as anticancer drug using modified pencil graphite electrode

Goserelin is an effective anticancer drug, but naturally causes several side effects. Hence the determination of this drug in biological samples, plays a key role in evaluating its effects and side effects. The current studies have concentrated on monitoring Goserelin using an easy and quick DNA biosensor for the first time. In this study, copper(II) oxide nanoparticles were created upon the surface of multiwalled carbon nanotubes (CuO/MWCNTs) as a conducting mediator. The modified pencil graphite electrode (ds-DNA/PA/CuO/MWCNTs/PGE) has been modified with the help of polyaniline (PA), ds-DNA, and CuO/MWCNTs nanocomposite. Additionally, the issue with the bio-electroanalytical guanine oxidation signal in relation to ds-DNA at the surface of PA/CuO/MWCNTs/PGE has been examined to determination Goserelin for the first time. It also, established a strong conductive condition to determination Goserelin in nanomolar concentration. Thus, Goserelin's determining, however, has a 0.21 nM detection limit and a 1.0 nM-110.0 µM linear dynamic range according to differential pulse voltammograms (DPV) of ds-DNA/PA/CuO/MWCNTs/PGE. Furthermore, the molecular docking investigation highlighted that Goserelin is able to bind ds-DNA preferentially and supported the findings of the experiments. The determining of Goserelin in real samples has been effectively accomplished in the last phase using ds-DNA/PA/CuO/MWCNTs/PGE.

Photocathodic Activation of Peroxymonosulfate in a Photofuel Cell: A Synergetic Signal Amplification Strategy for a Self-Powered Photoelectrochemical Sensor

A self-powered photoelectrochemical (PEC) sensor has attracted widespread attention in the field of analysis, but it is still a challenge to enhance its response signals with rational strategies. In this work, a novel self-powered PEC sensing platform was developed for the quantitative detection of gatifloxacin (GAT) based on a photofuel cell consisting of two types of ZIF-derived ZnO/Co3O4 heterojunctions as photoactive materials. Peroxymonosulfate (PMS) was first used as an electron acceptor coupled with a photofuel cell to develop a synergetic signal amplification strategy. In a dual-photoelectrode system, the PMS activation on the ZnO@Co3O4 photocathode not only accelerated electron transfer from the Co3O4@ZnO photoanode to achieve strong signal intensity but also improved the sensing sensitivity by the oxidation reaction of generated highly active radicals to GAT. Compared with the absence of electron acceptors, the introduction of PMS produced a 2-fold enhancement in the signal output performance and a more than 72-fold improvement in the signal sensitivity. For the construction of the sensing interface, a molecularly imprinted polymer was assembled on the photocathode to specifically recognize GAT. The proposed sensor exhibited a detection range of 10-1 to 105 pM with a detection limit of 0.065 pM. The proposed sensing method has the advantages of sensitivity, simplicity, reliable stability, and anti-interference ability, which opens the door to the design of high-performance self-powered PEC sensors.

A direct electrochemical sensor based on covalent organic frameworks/platinum nanoparticles for the detection of ofloxacin in water

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.

Engineering of CuMOF-SWCNTs@AuNPs-Based Electrochemical Sensors for Ultrasensitive and Selective Monitoring of Imatinib in Human Serum

Imatinib (IMA) is a common chemotherapy drug for the treatment of leukemia and can potentially lead to drug resistance and toxicity during the course of treatment. Monitoring IMA concentrations in body fluids is necessary to optimize therapeutic schedules and avoid overdosage. In this paper, a novel ultrasensitive electrochemical sensor based on CuMOF and SWCNTs@AuNPs was developed to determine this antileukemic drug. Herein, AuNPs were supported on carboxylic single-walled carbon nanotubes (SWCNT-COOH), and then poly(diallyldimethylammonium chloride) (PDDA) was used as a dispersant to overcome the internal van der Waals interactions among the CNTs, further increasing the AuNP loading. Moreover, the morphology, structure, composition, and electrochemical properties of the CuMOF-SWCNTs@AuNPs composite film were characterized using SEM, TEM, FT-IR, UV-vis, XRD, XPS, CV, and EIS. Due to the advantage of the superior electrocatalytic and conductive properties of SWCNTs@AuNPs and their preferable adsorptivity and affinity to IMA of CuMOF, the fabricated glassy carbon electrode significantly improved the determination performance via their synergetic amplified effect. Under optimal conditions, a wide linear response was exhibited in the range from 0.05 to 20.0 μM and the low detection limit of 5.2 nM. In addition, our prepared sensor has been applied to the analysis of IMA in blood serum samples with acceptable results. Therefore, our CuMOF-SWCNTs@AuNPs-based electrochemical sensor possessed prominent sensing responses for IMA, which could be used as a prospective approach in clinical application.

Amorphous amEu-NH2BDC and amTb-NH2BDC as ratio fluorescence probes for smartphone-integrated naked eye detection of bacillus anthracis biomarker

The abnormal concentration of anthrax spore biomarker 2,6-pyridinedicarboxylic acid (2,6-DPA) will seriously affect public health. Therefore, a sensitive and rapid assay for 2,6-DPA monitoring is of vital importance. In this work, novel nano-sized amorphous Eu-NH2BDC (amEu-NH2BDC) and amorphous Tb-NH2BDC (amTb-NH2BDC) metal organic frameworks are prepared by adjusting the ratio of metal and ligand, respectively. Both of them exhibit highly sensitive and selective ratiometric fluorescence detection for 2,6-DPA with wider linear range and lower detection limit in aqueous solutions and human serum. Attributed to the coordination effect of 2,6-DPA in triggering the characteristic fluorescence emissions of Eu3+or Tb3+ by replacing coordinated solvent molecules, as evidenced by ultraviolet-visible spectroscopy, the fluorescence lifetimes analysis, thermal gravimetric analysis, Fourier-transform infrared spectroscopy, density functional theory (DFT) simulations and X-ray photoelectron spectroscopy. In addition, the amEu-NH2BDC or amTb-NH2BDC loaded paper-based microsensors are constructed for real-time and sensitive detection of 2,6-DPA and coupled with a smartphone-assisted visual portable device.

Nanomaterial-based Electrochemical Sensors for Multiplex Medicinal Applications

This review explores the advancements in nanomaterial-based electrochemical sensors for the multiplex detection of medicinal compounds. The growing demand for efficient and selective detection methods in the pharmaceutical field has prompted significant research into the development of electrochemical sensors employing nanomaterials. These materials, defined as functional materials with at least one dimension between 1 and 100 nanometers, encompass metal nanoparticles, polymers, carbon-based nanocomposites, and nano-bioprobes. These sensors are characterized by their enhanced sensitivity and selectivity, playing a crucial role in simultaneous detection and offering a comprehensive analysis of multiple medicinal complexes within a single sample. The review comprehensively examines the design, fabrication, and application of nanomaterial- based electrochemical sensors, focusing on their ability to achieve multiplex detection of various medicinal substances. Insights into the strategies and nanomaterials employed for enhancing sensor performance are discussed. Additionally, the review explores the challenges and future perspectives of this evolving field, highlighting the potential impact of nanomaterial-based electrochemical sensors on the advancement of medicinal detection technologies.

Functionalities of electrochemical fluoroquinolone sensors and biosensors

Fluoroquinolones (FQs) are a class of broad-spectrum antimicrobial agents that are used to treat variety of infectious diseases. This class of antibiotics was being used for patients exhibiting early symptoms of a human respiratory disease known as the COVID-19 virus. As a result, this outbreak causes an increase in drug-resistant strains and environmental pollution, both of which pose serious threats to biota and human health. Thus, to ensure public health and prevent antimicrobial resistance, it is crucial to develop effective detection methods for FQs determination in water bodies even at trace levels. Due to their characteristics like specificity, selectivity, sensitivity, and low detection limits, electrochemical biosensors are promising future platforms for quick and on-site monitoring of FQs residues in a variety of samples when compared to conventional detection techniques. Despite their excellent properties, biosensor stability continues to be a problem even today. However, the integration of nanomaterials (NMs) could improve biocompatibility, stability, sensitivity, and speed of response in biosensors. This review concentrated on recent developments and contemporary methods in FQs biosensors. Furthermore, a variety of modification materials on the electrode surface are discussed. We also pay more attention to the practical applications of electrochemical biosensors for FQs detection. In addition, the existing challenges, outlook, and promising future perspectives in this field have been proposed. We hope that this review can serve as a bedrock for future researchers and provide new ideas for the development of electrochemical biosensors for antibiotics detection in the future.

Development of novel microsphere structured - calcium tungstate as efficacious electrocatalyst for the detection of antibiotic drug nitrofurantoin

In this report, synthetic and nitro groups containing antibiotic drug nitrofurantoin (NFT) were electrochemically quantified under amended conditions using novel constructed calcium tungstate microspheres modified on glassy carbon electrodes (CTMs/GCE). The calcium tungstate microspheres (CTMs) were synthesized by a facile sonochemical method and characterizations were done by various techniques, such as X-ray diffraction spectrometry (XRD), Fourier transform infrared spectroscopy (FTIR), Raman, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Ahead of this, electrochemical investigations were performed using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), amperometry, and linear sweep voltammetry (LSV). The synthesis of CTMs as well-distributed microspheres allows more active metal sites regarding and remarkable electrocatalytic activity towards NFT detection with excellent sensitivity (0.724 μA μM-1 cm-2) and low detection limit (21 nmol L-1) with a wide linear range 10-140 μM. The practical feasibility of the developed CTMs/GC electrode was elucidated using distinct real sample river tap water and clinical sample (NFT capsule), and thus, the modified electrode manifested acceptable recovery results.

An ultrasensitive ratiometric electrochemical aptasensor based on metal-organic frameworks and nanoflower-like Bi2CuO4 for human epidermal growth factor receptor 2 detection

An ultra-sensitive ratiometric electrochemical aptasensor was constructed based on metal-organic frameworks (MOFs) and bimetallic oxides for the detection of the human epidermal growth factor receptor 2 (HER2), a breast cancer marker. The aluminum metal-organic framework (Al-MOF) and cerium-metal-organic framework (Ce-MOF) have higher specific surface area, which is conducive to load more aptamers or complementary DNA (cDNA), and realize the amplification of internal reference signal Fc. Furthermore, nanoflower-like bismuth copper oxide (Bi2CuO4) with abundant active sites was introduced to modify more aptamers on its surface, which were then fixed to the glassy carbon electrode (GCE) to amplify the detection signal. The quantitative detection of HER2 was achieved by differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The materials were characterized by scanning electron microscope, transmission electron microscope, Zeta potential analyzer, X-ray diffraction and X-ray photoelectron spectroscopy. The ratiometric electrochemical aptasensor based on nanomaterial and chain displacement signal amplification technology could discern HER2 in a very wide range (0.001-20.0 ng/mL) with an extremely low detection limit (0.049 pg/mL) and has demonstrated good performance in clinical serum analysis. This strategy also provides a feasible idea for sensitive analysis of other clinical tumor markers.

Surface modification of a screen-printed electrode with a flower-like nanostructure to fabricate a guanine DNA-based electrochemical biosensor to determine the anticancer drug pemigatinib

The present study developed a DNA biosensor to determine pemigatinib for the first time. Three-dimensional carnation flower-like Eu3+:β-MnO2 nanostructures (3D CF-L Eu3+:β-MnO2 NSs) and a screen-printed electrode (SPE) modified with polyaniline (PA) were employed. The double-stranded DNA was also immobilized completely on the PA/3D CF-L Eu3+:β-MnO2 NSs/SPE. Then, electrochemical techniques were used for characterizing the modified electrode. After that, the interaction between pemigatinib and DNA was shown by a reduction in the oxidation current of guanine using differential pulse voltammetry (DPV). According to the analysis, the dynamic range of pemigatinib was between 0.001 and 180.0 μM, indicating the new electrode has a low limit of detection (LOD = 0.23 nM) for pemigatinib. Afterwards, pemigatinib in real samples was measured using the PA/3D CF-L Eu3+:β-MnO2 NSs/SPE loaded with ds-DNA. The proposed DNA biosensor showed good selectivity toward pemigatinib in the presence of other interference analytes, such as other ions, structurally related pharmaceuticals, and plasma proteins. In addition, the interaction site of pemigatinib with DNA was predicted by molecular docking, which showed the interaction of pemigatinib with the guanine bases of DNA through a groove binding mode. Finally, we employed the t-test to verify the capability of the ds-DNA/PA/3D CF-L Eu3+:β-MnO2 NSs/SPE for analyzing pemigatinib in real samples.

A nanoscale electrochemical guanine DNA-biosensor based on a flower-like nanocomposite of Tb-doped ZnO for the sensitive determination of pemetrexed

Pemetrexed is an antineoplastic drug used in chemotherapeutic treatments, especially in malignant mesothelioma and non-small cell lung carcinoma, but can also cause a variety of complications, like stomach pain, nausea, burning, vomiting, numbness, and tingling, emphasizing the need for an approach to quantify the drug in biological matrices. Herein, a DNA-based biosensor was introduced for pemetrexed determination. A hydrothermal approach was used for synthesizing flower-like nanoparticles (NPs) of zinc oxide (ZnO) doped with Tb (FL-NP Tb3+/ZnO). Moreover, energy dispersive X-ray (EDX), field-emission scanning electron microscopy (FESEM), zeta potential, Brunauer-Emmett-Teller (BET), and X-ray diffraction (XRD) analyses were used for characterizing the as-prepared nanocomposite. According to the impedance analysis, FL-NP Tb3+/ZnO was accompanied by very good electrochemical functions for a simple transfer of electrons. In the case of the immobilization of double-stranded deoxyribonucleic acid (ds-DNA) on the FL-NP Tb3+/ZnO and polypyrrole (PP)-modified pencil graphite electrode (ds-DNA/PP/FL-NP Tb3+/ZnO/PGE), a considerable enhancement was found in the electrochemical oxidation of guanine in ds-DNA residue bases. Since there was an interaction between ds-DNA and pemetrexed, the voltammetric current of guanine over the ds-DNA/PP/FL-NP Tb3+/ZnO/PGE declined in the presence of pemetrexed in the electrolytic solution. Moreover, under optimum conditions (25 mg L-1 of ds-DNA and 10 min incubation time, in acetate buffer at 25 °C), a linear decrease in the guanine signal was observed on the ds-DNA/PP/FL-NP Tb3+/ZnO/PGE as the pemetrexed concentration increased in the range from 0.001 μM to 175.0 μM with a limit of detection of 0.17 nM. Finally, the new DNA-based biosensor was successfully used for determining pemetrexed in real samples, indicating its application potential.

Fabrication of an electrochemical sensor based on eggshell waste recycling for the voltammetric simultaneous detection of the antibiotics ofloxacin and ciprofloxacin

In this work, an accurate, highly sensitive, and economical electrochemical sensor based on a carbon paste electrode modified by Ca2CuO3 nanostructure (Ca2CuO3 NS) was constructed using Eggshell waste recycling as a cheap source of calcium. The Ca2CuO3 NS was analyzed using FTIR, SEM, and XRD measurements. The synthesized nanomaterials utilized for the first time to enhance the electrocatalytic efficiency of carbon paste electrode (CPE) toward fluoroquinolones antibiotics ofloxacin (OFL) and ciprofloxacin (CIP), The drugs used to treat pneumonia caused by COVID-19. The synthesized Ca2CuO3 NS dramatically enhanced the anodic peak response of CPE toward both drugs compared to the unmodified one and other modified electrodes. The simultaneous detection of the two antibiotics was performed in the linear range of 0.09-1.0 μM for OFL and 0.05-0.8 μM for CIP with the LOD of 0.027 μM and 0.012 μM, respectively. The suggested method was applied successfully to determine OFL and CIP in real samples.

Electrochemical detection of kynurenic acid in the presence of tryptophan with the carbon paste electrode modified with the flower-like nanostructures of zinc oxide doped with terbium

With the help of a hydrothermal approach in this study, we could provide flower-like nanostructures (NSs) of zinc oxide (ZnO) doped with Tb (FL-NS Tb3+/ZnO). Then, FL-NS Tb3+/ZnO morphology was investigated by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and map analysis. The results revealed higher activity centers and porosity of this nanocomposite, which were followed by acceptable electrochemical function. Hence, it can be utilized for fabricating an electrochemical sensor with an appropriate response for the simultaneous determination of kynurenic acid (KYN) and tryptophan (TRP). However, as compared with the modified carbon paste electrode (FL-NS Tb3+/ZnO/CPE), the bare carbon paste electrode (BCPE) exhibited a weak response toward KYN and TRP but the modified electrode was followed by a high current response for KYN and TRP at a potential 0.35 and 0.809 V. Therefore, cyclic voltammetry (CV) was applied in optimal experimental conditions to study the electrochemical behaviors of KYN and TRP over the surface of the proposed modified electrode. Moreover, we used differential pulse voltammetry (DPV) for quantitative measurements. It was found that this new modified electrode linearly ranged from 0.001 to 700.0 μM, with detection limits of 0.34 nM and 0.22 nM for KYN and TRP, respectively. In addition, KYN and TRP in real samples can be analyzed by this sensor, with a recovery of 97.75%-103.6% for the spiked KYN and TRP in real samples.

Multivariate covalent organic frameworks guided carboxyl functionalized magnetic adsorbent for enrichment of fluoroquinolones in milk prior to high performance liquid chromatographic analysis

Herein, we prepared a carboxyl functionalized magnetic covalent organic framework (Fe3O4@iCOF-COOH) by combining multivariate synthetic strategy with post-synthetic modification. It was used as an adsorbent for magnetic solid phase extraction (MSPE) of six fluoroquinolones (FQs), and showed good absorption performance at neutral pH. Carboxyl groups are found to be crucial for the adsorption of fluoroquinolones. The adsorption mechanism was primarily attributed to strong hydrogen bonding, π-π interaction as well as potential hydrophobic effect. The optimal extraction conditions are sample pH at 6.0, adsorbent dosage of 3 mg, eluent of 1.0 mL methanol solution containing 7.5% ammonia, and extraction/desorption time of 30 min. Under the optimized conditions, the Fe3O4@iCOF-COOH was used as an adsorbent for MSPE of FQs in milk, an analytical method was established by combining with high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The limits of detection (LODs) and limit of quantification (LOQs) were 1.24-4.58 ng⋅mL-1 and 4.12-15.3 ng⋅mL-1, respectively. The recoveries of target FQs in spiked milk were 68.4-105%. This work provides a new way to prepare covalent organic framework based adsorbents for solid phase extraction, and can be readily extended to other type of adsorbents.

Single vs sandwich aptamers: Towards the detection of human epidermal growth factor receptor 2 using composites of phthalocyanine and nanoparticles

The superiority of the sandwich over a single aptamer based aptasensor assay for the detection of the human epidermal growth factor receptor 2 (HER2) is demonstrated for the first time. Cobalt tris-3,5 dimethoxy-phenoxy pyridine (5) oxy (2)- carboxylic acid phthalocyanine (CoMPhPyCPc) and sulphur/nitrogen doped graphene quantum dots (SNGQDs) and cerium oxide nanoparticles (CeO₂NPs) nanocomposite (SNGQDs@CeO₂NPs) were used for electrode modification of glassy carbon electrode (GCE) both individually and combined to form the substrates: GCE/SNGQDs@CeO₂NPs, GCE/CoMPhPyCPc and GCE/SNGQDs@CeO₂NPs/CoMPhPyCPc. The designed substrates were used as immobilization platforms for the amino functionalized HB5 aptamer for the development of both single and sandwich aptasensor assays. A novel bioconjugate, made of the HB5 aptamer and nanocomposite (HB5-SNGQDs@CeO₂NPs) was fabricated, and characterized using ultra-violet/visible, Fourier transform infrared, and Raman spectroscopies as well as scanning electron microscopy. HB5-SNGQDs@CeO₂NPs was applied as a secondary aptamer in the design of novel sandwich assays towards the electrochemical detection of HER2. The performance of the designed aptasensors were evaluated using electrochemical impedance spectroscopy. The sandwich assay gave low limit of detection of 0.00088 pg/mL, high sensitivity of 773925 Ω pg^-1mL, showed stability, and good precision in real samples towards HER2 detection.

A molecularly imprinted electrochemical sensor with dual functional monomers for selective determination of gatifloxacin

A molecularly imprinted electrochemical sensor was designed for the selective determination of gatifloxacin (GTX) based on dual functional monomers. Multi-walled carbon nanotube (MWCNT) enhanced the current intensity and zeolitic imidazolate framework 8 (ZIF8) provided a large surface area to produce more imprinted cavities. In the electropolymerization of molecularly imprinted polymer (MIP), p-aminobenzoic acid (p-ABA) and nicotinamide (NA) were used as dual functional monomers, and GTX was the template molecule. Taking [Fe(CN)6]3-/4- as an electrochemical probe, an oxidation peak on the glassy carbon electrode was located at about 0.16 V (vs. saturated calomel electrode). Due to the diverse interactions among p-ABA, NA, and GTX, the MIP-dual sensor exhibited higher specificity towards GTX than MIP-p-ABA and MIP-NA sensors. The sensor had a wide linear range from 1.00 × 10-14 to 1.00 × 10-7 M with a low detection limit of 2.61 × 10-15 M. Satisfactory recovery between 96.5 and 105% with relative standard deviation from 2.4 to 3.7% in real water samples evidenced the potential of the method in antibiotic contaminant determination.

Sensitivity enhancement of a Cu (II) metal organic framework-acetylene black-based electrochemical sensor for ultrasensitive detection of imatinib in clinical samples

Imatinib (IMB), an anticancer drug, is extensively used for chemotherapy to improve the quality of life of cancer patients. The aim of therapeutic drug monitoring (TDM) is to guide and evaluate the medicinal therapy, and then optimize the clinical effect of individual dosing regimens. In this work, a highly sensitive and selective electrochemical sensor based on glassy carbon electrode (GCE) modified with acetylene black (AB) and a Cu (II) metal organic framework (CuMOF) was developed to measure the concentration of IMB. CuMOF with preferable adsorbability and AB with excellent electrical conductivity functioned cooperatively to enhance the analytical determination of IMB. The modified electrodes were characterized using X-rays diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FT-IR), ultraviolet and visible spectrophotometry (UV-vis), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), brunauer‒emmett‒teller (BET) and barrett‒joyner‒halenda (BJH) techniques. Analytical parameters such as the ratio of CuMOF to AB, dropping volumes, pH, scanning rate and accumulation time were investigated through cyclic voltammetry (CV). Under optimal conditions, the sensor exhibited an excellent electrocatalytic response for IMB detection, and two linear detection ranges were obatined of 2.5 nM-1.0 μM and 1.0-6.0 μM with a detection limit (DL) of 1.7 nM (S/N = 3). Finally, the good electroanalytical ability of CuMOF-AB/GCE sensor facilitated the successful determination of IMB in human serum samples. Due to its acceptable selectivity, repeatability and long-term stability, this sensor shows promising application prospects in the detection of IMB in clinical samples.

Nickel-Cobalt Salen Organometallic Complexes Encapsulated in Mesoporous NaA Nanozeolite for Electrocatalytic Quantification of Ascorbic Acid and Paracetamol

Goal of current study was fabrication of novel voltammetric nanosensor for the synchronize quantification of ascorbic acid (AA) and paracetamol (PAR) by nickel-cobalt salen complexes encapsulated in the supercages of NaA nanozeolite modified carbon paste electrode (NiCoSalenA/CPE). For this purpose, NiCoSalenA nanocomposite was firstly prepared and characterized by various methods. Also, cyclic voltammetry (CV), choronoamperometry (CHA) and differential pulse voltammetry (DPV) were utilized to evaluate performance of the modified electrodes. The effects of pH and modifier amount were considered on the electrochemical oxidation of AA and PAR on the surface of NiCoSalenA/CPE. Results from this method indicated that pH of 3.0 in phosphate buffer solution (0.1 M) and 15 wt% of NiCoSalenA nanocomposite in the modified CPE results in the maximum current density. The oxidation signals of AA and PAR was amplified affectively at NiCoSalenA/CPE versus unmodified CPE. The limit of detection (LOD) and linear dynamic range (LDR) for the simultaneous measurement of them were founds to be 0.82 and 2.73-80.70 for AA and 0.51 µM, 1.71-32.50 and 32.50-137.60 µM for PAR, respectively. The catalytic rate constants (kcat) were attained to be 3.73 × 107 and 1.27 × 107 cm3 mol-1 s-1 for AA and PAR via CHA method, respectively. Also, the amounts of diffusion coefficient (D) were found to be 1.12 × 10-7 and 1.92 × 10-7 cm2 s-1 for AA and PAR, respectively. The average value of electron transfer rate constant between NiCoSalenA/CPE and PAR was obtained to be 0.016 s-1. The NiCoSalen-A/CPE displayed worthy stability, repeatability and extraordinary recovery for simultaneous measurements of AA and PAR. Application of offered sensor was confirmed by quantifying concentrations of AA and PAR in human serum solution as a real sample.