Electrochemical sensing of methotrexate in the presence of folic acid using PAMAM dendrimer-functionalized multiwalled carbon nanotube-modified electrode.

This works presents a novel electrochemical sensor based on the third-generation poly(amidoamine) dendrimer (G3 PAMAM)-functionalized multiwalled carbon nanotube (MWCNT)-modified screen-printed graphite electrode (SPGE) for the simple and sensitive detection of methotrexate (MTX). The carboxylated MWCNTs were covalently functionalized with amino groups of G3 PAMAM and characterized using different techniques. The sensing ability of the designed nanosensor (MWCNTs-PAMAM/SPGE) was tested using differential pulse voltammetry (DPV), chronoamperometry (CHA), linear sweep voltammetry (LSV), and cyclic voltammetry (CV). To investigate the electrocatalytic activity of PAMAM-functionalized MWCNTs, a comparative electrochemical analysis was carried out and it was determined that PAMAM-functionalized MWCNT-modified SPGE showed good electrocatalytic performance for MTX oxidation compared to the unmodified SPGE. The MWCNT-PAMAM/SPGE lead to a reduced overpotential of MTX oxidation of about 300 mV and enhanced current of about 9 µA of the unmodified SPGE. Experiments were performed for the quantitative determination of MTX using the DPV technique. The response peak current linearly related against MTX concentration in the ranges from 0.01 to 110.0 µM and a limit of detection (LOD) equal to 0.003 µM. Also, MWCNT-PAMAM/SPGE exhibits good catalytic ability toward MTX determination in the presence of folic acid (FA), and the separation of their oxidation peaks (peak potential difference = 320 mV) simultaneously detected the above compounds. To prove the applicability of the MWCNT-PAMAM/SPGE sensor, the concentrations of MTX and FA in pharmaceutical products and biological samples were determined. The calculated recoveries were close to 100%, which indicates that the method might be assumed to be accurate.

A UiO-66-NH2 MOF/PAMAM Dendrimer Nanocomposite for Electrochemical Detection of Tramadol in the Presence of Acetaminophen in Pharmaceutical Formulations.

In this work, we prepared a novel electrochemical sensor for the detection of tramadol based on a UiO-66-NH2 metal-organic framework (UiO-66-NH2 MOF)/third-generation poly(amidoamine) dendrimer (G3-PAMAM dendrimer) nanocomposite drop-cast onto a glassy carbon electrode (GCE) surface. After the synthesis of the nanocomposite, the functionalization of the UiO-66-NH2 MOF by G3-PAMAM was confirmed by various techniques including X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field emission-scanning electron microscopy (FE-SEM), and Fourier transform infrared (FT-IR) spectroscopy. The UiO-66-NH2 MOF/PAMAM-modified GCE exhibited commendable electrocatalytic performance toward the tramadol oxidation owing to the integration of the UiO-66-NH2 MOF with the PAMAM dendrimer. According to differential pulse voltammetry (DPV), it was possible to detect tramadol under optimized circumstances in a broad concentration range (0.5 µM-500.0 µM) and a narrow limit of detection (0.2 µM). In addition, the stability, repeatability, and reproducibility of the presented UiO-66-NH2 MOF/PAMAM/GCE sensor were also studied. The sensor also possessed an acceptable catalytic behavior for the tramadol determination in the co-existence of acetaminophen, with the separated oxidation potential of ΔE = 410 mV. Finally, the UiO-66-NH2 MOF/PAMAM-modified GCE exhibited satisfactory practical ability in pharmaceutical formulations (tramadol tablets and acetaminophen tablets).

Molybdenum Disulfide/Nickel-Metal Organic Framework Hybrid Nanosheets Based Disposable Electrochemical Sensor for Determination of 4-Aminophenol in Presence of Acetaminophen.

The toxicity of commonly used drugs, such as acetaminophen (ACAP) and its degradation-derived metabolite of 4-aminophenol (4-AP), underscores the need to achieve an effective approach in their simultaneous electrochemical determination. Hence, the present study attempts to introduce an ultra-sensitive disposable electrochemical 4-AP and ACAP sensor based on surface modification of a screen-printed graphite electrode (SPGE) with a combination of MoS2 nanosheets and a nickel-based metal organic framework (MoS2/Ni-MOF/SPGE sensor). A simple hydrothermal protocol was implemented to fabricate MoS2/Ni-MOF hybrid nanosheets, which was subsequently tested for properties using valid techniques including X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transformed infrared spectroscopy (FTIR), and N2 adsorption-desorption isotherm. The 4-AP detection behavior on MoS2/Ni-MOF/SPGE sensor was followed by cyclic voltammetry (CV), chronoamperometry and differential pulse voltammetry (DPV). Our experimental findings on the generated sensor confirmed a broad linear dynamic range (LDR) for 4-AP from 0.1 to 600 µM with a high sensitivity of 0.0666 µA/µM and a low limit of detection (LOD) of 0.04 µM. In addition, an analysis of real specimens such as tap water sample as well as a commercial sample (acetaminophen tablets) illuminated the successful applicability of as-developed sensor in determining ACAP and 4-AP, with an impressive recovery rate.

Simultaneous Voltammetric Determination of Epinine and Venlafaxine Using Disposable Screen-Printed Graphite Electrode Modified by Bimetallic Ni-Co-Metal-Organic-Framework Nanosheets.

We constructed two-dimensional NiCo-metal-organic-framework (NiCo-MOF) nanosheets based on a facile protocol and then characterized them using multiple approaches (X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field emission-scanning electron microscopy (FE-SEM), and N2 adsorption/desorption isotherms techniques). As a sensitive electroactive material, the as-fabricated bimetallic NiCo-MOF nanosheets were employed to modify a screen-printed graphite electrode surface (NiCo-MOF/SPGE) for epinine electro-oxidation. According to the findings, there was a great improvement in the current responses of the epinine because of the appreciable electron transfer reaction and catalytic performance of the as-produced NiCo-MOF nanosheets. Differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry were utilized to analyze the electrochemical activity of the epinine on the NiCo-MOF/SPGE. A linear calibration plot was obtained in the broad concentration range (0.07-335.0 µM) with a high sensitivity (0.1173 µA/µM) and a commendable correlation coefficient (0.9997). The limit of detection (S/N = 3) was estimated at 0.02 µM for the epinine. According to findings from DPV, the electrochemical sensor of the NiCo-MOF/SPGE could co-detect epinine and venlafaxine. The repeatability, reproducibility and stability of the NiCo-metal-organic-framework-nanosheets-modified electrode were investigated, and the relative standard deviations obtained indicated that the NiCo-MOF/SPGE had superior repeatability, reproducibility and stability. The as-constructed sensor was successfully applicable in sensing the study analytes in real specimens.

Graphene Oxide-PAMAM Nanocomposite and Ionic Liquid Modified Carbon Paste Electrode: An Efficient Electrochemical Sensor for Simultaneous Determination of Catechol and Resorcinol.

In this paper, a simple strategy was proposed for the analysis of catechol by a carbon paste electrode (CPE) modified with graphene oxide-third generation of poly(amidoamine) dendrimer (GO/G3-PAMAM) nanocomposite and ionic liquid (IL). The synthesis of GO-PAMAM nanocomposite was confirmed using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), and Fourier transform infrared spectroscopy (FT-IR) techniques. The prepared modified electrode (GO-PAMAM/ILCPE) exhibited good performance to detect catechol with a notable decrease in overpotential and increase in current compared with an unmodified CPE. Under optimum experimental conditions, GO-PAMAM/ILCPE electrochemical sensors indicated a lower limit of detection (LOD) of 0.034 µM and a linear response in the concentration range of 0.1 to 200.0 µM for the quantitative measurement of catechol in aqueous solutions. In addition, GO-PAMAM/ILCPE sensor exhibited an ability to simultaneously determine catechol and resorcinol. It can be found that catechol and resorcinol could be completely separated on the GO-PAMAM/ILCPE with the differential pulse voltammetry (DPV) technique. Finally, a GO-PAMAM/ILCPE sensor was utilized to detect catechol and resorcinol in water samples with recoveries of 96.2% to 103.3% and relative standard deviations (RSDs) of less than 1.7%.

Simultaneous Determination of Dopamine and Uric Acid in Real Samples Using a Voltammetric Nanosensor Based on Co-MOF, Graphene Oxide, and 1-Methyl-3-butylimidazolium Bromide.

A chemically modified carbon paste electrode, based on a CoMOF-graphene oxide (GO) and an ionic liquid of 1-methyl-3-butylimidazolium bromide (CoMOF-GO/1-M,3-BB/CPE), was fabricated for the simultaneous determination of dopamine (DA) and uric acid (UA). The prepared CoMOF/GO nanocomposite was characterized by field emission-scanning electron microscopy (FE-SEM), the X-ray diffraction (XRD) method, a N2 adsorption-desorption isotherm, and an energy dispersive spectrometer (EDS). The electrochemical sensor clearly illustrated catalytic activity towards the redox reaction of dopamine (DA), which can be authenticated by comparing the increased oxidation peak current with the bare carbon paste electrode. The CoMOF-GO/1-M,3-BB/CPE exhibits a wide linear response for DA in the concentration range of 0.1 to 300.0 µM, with a detection limit of 0.04 µM. The oxidation peaks' potential for DA and uric acid (UA) were separated well in the mixture containing the two compounds. This study demonstrated a simple and effective method for detecting DA and UA in real samples.

Construction of modified screen-printed graphite electrode for the application in electrochemical detection of sunset yellow in food samples.

The current work introduced a novel electrochemical sensor (screen-printed graphite electrode (SPGE) modified with MnO2 nanorods anchored graphene oxide nanocomposite (MnO2 NRs/GO) for sensitive determination of sunset yellow. The characterization of MnO2 NRs/GO nanocomposite synthesized through a simple hydrothermal approach was determined employing varied analytical equipment like Field emission-scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). Chronoamperometric measurements, differential pulse voltammetry (DPV), cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were recruited to recognize the electrochemical oxidation of sunset yellow on the MnO2 NRs/GO/SPGE. The results of CV proved that the as-synthesized MnO2 NRs/GO nanocomposite has a good electrocatalytic activity toward sunset yellow. The MnO2 NRs/GO/SPGE electrode under optimized conditions using the DPV possessed a linear response for different concentrations of sunset yellow (between 0.01 and 115.0 µM) with a low limit of detection (LOD) (0.008 µM). Finally, the impressive applicability of this sensor was confirmed via real sample analysis with excellent recoveries (between 97.3 and 104.6%).

A Comprehensive Review of Metal-Organic Framework: Synthesis, Characterization, and Investigation of Their Application in Electrochemical Biosensors for Biomedical Analysis.

Many studies have addressed electrochemical biosensors because of their simple synthesis process, adjustability, simplification, manipulation of materials' compositions and features, and wide ranges of detection of different kinds of biomedical analytes. Performant electrochemical biosensors can be achieved by selecting materials that enable faster electron transfer, larger surface areas, very good electrocatalytic activities, and numerous sites for bioconjugation. Several studies have been conducted on the metal-organic frameworks (MOFs) as electrode modifiers for electrochemical biosensing applications because of their respective acceptable properties and effectiveness. Nonetheless, researchers face challenges in designing and preparing MOFs that exhibit higher stability, sensitivity, and selectivity to detect biomedical analytes. The present review explains the synthesis and description of MOFs, and their relative uses as biosensors in the healthcare sector by dealing with the biosensors for drugs, biomolecules, as well as biomarkers with smaller molecular weight, proteins, and infectious disease.

Amplified electrochemical sensor employing screen-printed electrode modified with Ni-ZIF-67 nanocomposite for high sensitive analysis of Sudan I in present bisphenol A.

This study utilized a facile one-pot protocol to synthesize Ni-cobalt zeolitic imidazolate framework (Ni-ZIF-67) nanocomposite, which was then characterized by Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and scanning electron microscopy. The Ni-ZIF-67 nanocomposite was subsequently applied to modify a screen-printed electrode (SPE) as a durable sensor for detection of Sudan I concomitantly with bisphenol A (BPA), with remarkably increased electrochemical response when comparing with a bare SPE. The results showed the calibration plot to be linear in the concentration range between 0.03 µM and 535.0 µM, with a narrow limit of detection of 9.0 nM (S/N = 3). Our proposed protocol was successful in detecting target analytes in real tap water and food specimens.

Simultaneous detection of carmoisine and tartrazine in food samples using GO-Fe3O4-PAMAM and ionic liquid based electrochemical sensor.

This study was performed to investigate the simultaneous detection of carmoisine and tartrazine, two food azo dyes, with a new voltammetric sensor based on graphene oxide-Fe3O4 (GO-Fe3O4) nanocomposite functionalized with fourth-generation poly(amidoamine) (G4 PAMAM) dendrimers (GO-Fe3O4-G4 PAMAM) and ionic liquid (IL) modified carbon paste electrode (GO-Fe3O4-G4 PAMAM/ILCPE). The GO-Fe3O4-G4 PAMAM was synthesized and characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), vibrating-sample magnetometer (VSM), and fourier transform infrared (FT-IR) techniques. Cyclic voltammetry (CV) was used to evaluate the electrochemical behavior of carmoisine, revealing the good electrocatalytic function of GO-Fe3O4-G4 PAMAM/ILCPE. Linear response from 0.1 to 170.0 µM was obtained based on carmoisine electrochemical oxidation through differential pulse voltammetry (DPV). The limit of detection (LOD) value obtained was 0.02 µM. Also, the GO-Fe3O4-G4 PAMAM/ILCPE was used for the simultaneous determination of carmoisine and tartrazine. In co-existence system containing carmoisine and tartrazine, the developed sensor exhibited well-defined and separate DPV peaks (i.e., 770 mV) for carmoisine and tartrazine. Besides, repeatability, reproducibility and stability studies were performed. Additionally, the analytical application of this sensor was demonstrated by determination of carmoisine and tartrazine in food samples including lemon juice and powdered juice.

Synthesis and Characterization of GO/ZIF-67 Nanocomposite: Investigation of Catalytic Activity for the Determination of Epinine in the Presence of Dobutamine.

In this study, we prepared graphene oxide (GO)/ZIF-67 nanocomposites. Therefore, GO/ZIF-67 nanocomposites were used as a modifier on a screen-printed electrode (GO/ZIF-67/SPE) for studying the electrochemical behavior of epinine in phosphate buffer saline (PBS) at pH 7.0 with voltammetry techniques. The GO/ZIF-67/SPE showed greater electrocatalytic activities than the bare SPE. As a result, the GO/ZIF-67/SPE was utilized for additional electrochemical examinations. The epinine concentration determination was in the range 9.0 × 10-8 M to 5.0 × 10-4 M, and the limit of detection (LOD) as well as the limit of quantification (LOQ) equaled 2.0 and 6.6 nM, respectively. From the scan rate study, the oxidation of epinine was found to be diffusion-controlled, and the simultaneous detection of epinine and dobutamine were well achieved with the differential pulse voltammetric (DPV) technique. Moreover, the stability and reproducibility of epinine at the GO/ZIF-67/SPE was studied, and the use of the GO/ZIF-67/SPE to detect epinine and dobutamine in real samples was furthermore successfully demonstrated.

Green Synthesis of Zeolitic Imidazolate Frameworks: A Review of Their Characterization and Industrial and Medical Applications.

Metal organic frameworks (MOF) are a class of hybrid networks of supramolecular solid materials comprising a large number of inorganic and organic linkers, all bound to metal ions in a well-organized fashion. Zeolitic imidazolate frameworks (ZIFs) are a sub-group of MOFs with imidazole as an organic linker to metals; it is rich in carbon, nitrogen, and transition metals. ZIFs combine the classical zeolite characteristics of thermal and chemical stability with pore-size tunability and the rich topological diversity of MOFs. Due to the energy crisis and the existence of organic solvents that lead to environmental hazards, considerable research efforts have been devoted to devising clean and sustainable synthesis routes for ZIFs to reduce the environmental impact of their preparation. Green chemistry is the key to sustainable development, as it will lead to new solutions to existing problems. Moreover, it will present opportunities for new processes and products and, at its heart, is scientific and technological innovation. The green chemistry approach seeks to redesign the materials that make up the basis of our society and our economy, including the materials that generate, store, and transport our energy, in ways that are benign for humans and the environment and that possess intrinsic sustainability. This study covers the principles of green chemistry as used in designing strategies for synthesizing greener, less toxic ZIFs the consume less energy to produce. First, the necessity of green methods in today's society, their replacement of the usual non-green methods and their benefits are discussed; then, various methods for the green synthesis of ZIF compounds, such as hydrothermally, ionothermally, and by the electrospray technique, are considered. These methods use the least harmful and toxic substances, especially concerning organic solvents, and are also more economical. When a compound is synthesized by a green method, a question arises as to whether these compounds can replace the same compounds as synthesized by non-green methods. For example, is the thermal stability of these compounds (which is one of the most important features of ZIFs) preserved? Therefore, after studying the methods of identifying these compounds, in the last part, there is an in-depth discussion on the various applications of these green-synthesized compounds.

Low-temperature synthesis of hetero-structures of magnetically separable iron oxide@Au-rGO nanocomposite for efficient degradation of organic dye under visible light irradiation.

In the present study, Fe3O4@Au core-shell nanoparticles decorated on reduce graphene oxide (Fe3O4@Au/rGO) nanocomposite were synthesized using the reduction method by sodium citrate, Hummer's method, and hydrothermal method, respectively. The as-prepared nanostructures were characterized by X-ray diffraction (XRD), Energy Dispersive X-ray (EDX), transmission electron microscopy (TEM), scanning electron microscopy (SEM)to assess the surface features, crystallinity and morphological characteristics. These nanostructures were employed for photocatalytic degradation of crystal violet (CV), and amongst them, Fe3O4@Au/rGO nanocomposite offered the best results under the visible light irradiation and optimal conditions. The effect of the amount of nano-photocatalyst, initial CV concentration, the initial pH, temperature, stirring speed, and degradation time was evaluated individually. A 100% degradation was obtained after 1 min in the presence of 0.008 g nano-photocatalyst, and also 100% of degradation was achieved after 5 min in the presence of 0.005 g of the prepared nano-photocatalyst. After a few tests, its photocatalytic performance was retained, implying the superior stability of Fe3O4@Au/rGO nanocomposite. The kinetic study of photocatalytic degradation also indicated that the fit model for the kinetic reaction was the pseudo-second-order kinetic model. Finally, the photocatalytic degradation of real samples with synthesized nanocomposite showed promising results.

Voltammetric detection of sumatriptan in the presence of naproxen using Fe3O4@ZIF-8 nanoparticles modified screen printed graphite electrode.

A novel electrochemical sensing platform was designed and prepared for the simultaneous detection of sumatriptan and naproxen by exploiting the prowess of the Fe3O4@ZIF-8 nanoparticles (NPs); as-synthesized Fe3O4@ZIF-8 NPs were characterized by energy-dispersive X-ray spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy (FESEM), transmission electron microscopy and thermal gravimetric analysis. The immobilized Fe3O4@ZIF-8 NPs on a screen printed graphite electrode (SPGE) was evaluated electrochemically via cyclic voltammetry, linear sweep voltammetry, and differential pulse voltammetry as well as chronoamprometery means; Fe3O4@ZIF-8/SPGE exhibited good sensing performance for sumatriptan in a range of 0.035-475.0 µM with detection limit of 0.012 µM. Also, Fe3O4@ZIF-8/SPGE exhibited good sensing performance for naproxen in a range of 0.1-700.0 µM with detection limit of 0.03 µM. The modified electrode showed two separate oxidative peaks at 620 mV for sumatriptan and at 830 mV for naproxen with a peak potential separation of 210 mV which was large enough to detect the two drugs simultaneously besides being stable in the long-run with considerable reproducibility. Real sample analyses were carried out to identify the function of fabricated electrode in sensing applications wherein trace amounts of sumatriptan and naproxen could be identified in these samples.

Magnetic nanomaterials based electrochemical (bio)sensors for food analysis.

It is widely accepted that nanotechnology attracted more interest because of various values that nanomaterial applications offers in different fields. Recently, researchers have proposed nanomaterials based electrochemical sensors and biosensors as one of the potent alternatives or supplementary analytical tools to the conventional detection procedures that consumes a lot of time. Among different nanomaterials, researchers largely considered magnetic nanomaterials (MNMs) for developing and fabricating the electrochemical (bio)sensors for numerous utilizations. Among several factors, healthier and higher quality foods are the most important preferences of consumers and manufacturers. For this reason, developing new techniques for rapid, precise as well as sensitive determination of components or contaminants of foods is very important. Therefore, developing the new electrochemical (bio)sensors in food analysis is one of the key and effervescent research fields. In this review, firstly, we presented the properties and synthesis strategies of MNMs. Then, we summarized some of the recently developed MNMs-based electrochemical (bio)sensors for food analysis including detecting the antioxidants, synthetic food colorants, pesticides, heavy metal ions, antibiotics and other analytes (bisphenol A, nitrite and aflatoxins) from 2010 to 2020. Finally, the present review described advantages, challenges as well as future directions in this field.

Recent developments in voltammetric and amperometric sensors for cysteine detection.

This review article aims to provide an overview of the recent advances in the voltammetric and amperometric sensing of cysteine (Cys). The introduction summarizes the important role of Cys as an essential amino acid, techniques for its sensing, and the utilization of electrochemical methods and chemically modified electrodes for its determination. The main section covers voltammetric and amperometric sensing of Cys based on glassy carbon electrodes, screen printed electrodes, and carbon paste electrodes, modified with various electrocatalytic materials. The conclusion section discusses the current challenges of Cys determination and the future perspectives.

Fabrication of a new superparamagnetic metal-organic framework with core-shell nanocomposite structures: Characterization, biocompatibility, and drug release study.

The Superparamagnetic CoFe2O4NPs@Mn-Organic Framework core-shell nanocomposites that had potential application in targeted drug-delivery were synthesized by layer to layer method. The structure and composition of the obtained microspheres were characterized by SEM, TEM, DLS, XRD, VSM, FTIR, and TG analysis. Results showed that the structures have a high degree crystalline, high temperature stability, magnetics and core-shell nanocomposites. Therefore, it is an excellent candidate for drug delivery systems. Afterwards, Daunorubicin (as a drug model) was laden in the MOFs by a Simple stirring. For comparison of magnetic properties of MOFs for drug delivery, an external magnetic field applied to the plate to evaluate the efficiency. The external magnetic field significantly increases anti-tumor activity of formulation (drug+ MOFs). The results showed that MOFs are biocompatible, which endue MOFs great potential in targeting drug-delivery systems with enhanced efficiency.

Simultaneous electrochemical determination of levodopa and piroxicam using a glassy carbon electrode modified with a ZnO-Pd/CNT nanocomposite.

A highly conductive electrochemical sensor was constructed for the simultaneous electrochemical determination of levodopa and piroxicam by modification of a glassy carbon electrode with a ZnO-Pd/CNT nanocomposite (GCE/ZnO-Pd/CNTs). The ZnO-Pd/CNT nanocomposite was synthesized by the sol-gel procedure and was characterized by EDAX, MAP and SEM. The sensor was shown to improve the oxidation signal of levodopa and piroxicam by ∼70.2-fold and ∼41.5-fold, respectively. This marks the first time that the electrochemical behavior of levodopa and piroxicam have been investigated at the surface of GCE/ZnO-Pd/CNTs. The voltammogram showed a quasi-reversible signal and an irreversible redox signal for electro-oxidation of levodopa and piroxicam, respectively. The GCE/ZnO-Pd/CNTs showed a linear dynamic range of 0.6 to 100.0 µM (at a potential of ∼180 mV) and 0.1 to 90 µM (at a potential of ∼480 mV) with detection limits of 0.08 and 0.04 µM for the determination of levodopa and piroxicam, respectively. GCE/ZnO-Pd/CNTs were then applied for the determination of levodopa and piroxicam in real samples.

Fabrication of novel TiO2 nanoparticles/Mn(III) salen doped carbon paste electrode: application as electrochemical sensor for the determination of hydrazine in the presence of phenol.

Hydrazine and phenol are two important environmental pollutants. In this work, an electrochemical sensor for the selective and sensitive detection of hydrazine in presence of phenol was developed by the bulk modification of carbon paste electrode (CPE) with TiO2 nanoparticles and Mn(III) salen. Large peak separation, good sensitivity, and stability allow this modified electrode to analyze hydrazine individually and simultaneously along with phenol. Applying square wave voltammetry (SWV), a linear dynamic range of 3 × 10(-8)-4.0 × 10(-4) M with detection limit of 10.0 nM was obtained for hydrazine. Finally, the proposed method was applied to the determination of hydrazine and phenol in some real samples.

Synthesis, characterization, X-ray crystal structure, DFT calculation, DNA binding, and antimicrobial assays of two new mixed-ligand copper(II) complexes.

Two new Cu(II) complexes, [Cu(L)(phen)] (1), [Cu(L)(bipy)] (2), where L(2-)=(3-methoxy-2oxidobenzylidene)benzohydrazidato, phen=1,10 phenanthroline, and bipy=2,2' bipyridine, were prepared and fully characterized using elemental analyses, FT-IR, molar conductivity, and electronic spectra. The structures of both complexes were also determined by X-ray diffraction. It was found that, both complexes possessed square pyramidal coordination environment in which, Cu(II) ions were coordinated by donor atoms of HL and two nitrogens of heterocyclic bases. Computational studies were performed using DFT calculations at B3LYP/6-311+G(d,p) level of theory. DNA binding activities of these complexes were also investigated using electronic absorption, competitive fluorescence titration and cyclic voltammetry studies. The obtained results indicated that binding of the complexes to DNA was of intercalative mode. Furthermore, antimicrobial activities of these compounds were screened against microorganisms.