Preparation of high-performance supercapacitor electrode with nanocomposite of CuO/NCNO flower-like.

Due to the importance of energy storage systems based on supercapacitors, various studies have been conducted. In this research CuO, NCNO and the flower like CuO/NCNO have been studied as a novel materials in this field. The resulte showed that the synthesized CuO nanostructutes have flower like morphology which studied by FE-SEM analisis. Further, the XRD pattern confirmed the crystalline properties of the CuO/NCNO nanocomposite, and the Raman verified the functional groups and vibrations of the components of CuO/NCNO nanocomposite. In a two-electrode system at a current density of 4 A/g, the capacitance, power density, and energy density were 450 F/g, 3200 W/kg, and 98 Wh/kg, respectively. The charge transfer resistances of CuO and NCNO/CuO electrodes obtained 8 and 2 Ω respectively, which show that the conductivity and supercapacitive properties of nanocomposite are better than pure components. Also, the stability and low charge transfer resistance are other advantages obtained in a two-symmetrical electrode investigation. The stability investigation showed that after 3000 consecutive cycles, only 4% of the initial capacitance of the CuO/NCNO electrode decreased.

Preparation of a Highly Sensitive Electrochemical Aptasensor for Measuring Epirubicin Based on a Gold Electrode Boosted with Carbon Nano-Onions and MB.

Epirubicin is prescribed as an essential drug for treating breast, prostate, uterine, and gastrointestinal cancers. It has many side effects, such as heart failure, mouth inflammation, abdominal pain, fever, and shortness of breath. Its measurement is necessary by straightforward and cheap methods. The application of aptamer-based electrochemical sensors is accounted as a selective option for measuring different compounds. In this work, a thiol-modified aptamer was self-assembled on the surface of the gold electrode (AuE) boosted with carbon nano-onions (CNOs), and coupled with methylene blue (MB) as an electroactive tracker to achieve a sensitive and selective aptasensor. In the absence of the epirubicin, CNOs binds to the aptamer through a π-π interaction enhancing the MB electrochemical signal. When epirubicin binds to the aptamer, the adsorption of CNOs and MB to the aptamer is not well established, so the electrochemical signal is reduced, consequently, the epirubicin value can be measured. The prepared aptasensor demonstrated an excellent sensitivity with a curve slope of 0.36 µI/nM, and 3 nM limit of detection in the linear concentration range of 1-75 nM. The prepared aptasensor was accurately capable of measuring epirubicin in blood serum samples.

Architecting of an aptasensor for the staphylococcus aureus analysis by modification of the screen-printed carbon electrode with aptamer/Ag-Cs-Gr QDs/NTiO2.

Given the many issues bacterial infections cause to humans and the necessity for their detection, in this work we developed a robust aptasensor for prompt, ultrasensitive, and selective analysis of staphylococcus aureus bacterium (S. aureus). A nanocomposite of Ag nanoparticles, chitosan, graphene quantum dots, and nitrogen-doped TiO2 nanoparticles (Ag-Cs-Gr QDs/NTiO2) was synthesized, and thoroughly characterized by XRD, FT-IR, and FE-SEM spectroscopic methods. The surface of screen-printed carbon electrodes modified with Ag-Cs-Gr QDs/NTiO2 nanocomposite was utilized as a compatible platform for aptamer attachment. The aptasensor accurately determined S. aureus in the dynamic range of 10-5 × 108 CFU/mL with detection limit of 3.3 CFU/mL. The monitoring of the practical performance of aptasensor in human serum samples revealed its superiority over the conventional methods (relative recovery of 96.25-103.33%). The Ag-Cs-Gr QDs/NTiO2-based aptasensor offers facile, biocompatibility, good repeatability, reproducibility (RSD = 3.66%), label free and stabile strategy for sensitive S. aureus analysis free from biomolecules interferences in actual specimens.

Evaluation of MXene as an adsorbent in dispersive solid phase extraction of several pesticides from fresh fruit juices prior to their determination by HPLC-MS/MS.

This study aimed to introduce a dispersive solid phase extraction method based on MXene nanoparticles as a novel sorbent for the simultaneous extraction and determination of twelve pesticides from fresh fruit juices. In the following, a high performance liquid chromatography-tandem mass spectrometry was used for their determination in the samples. In this method, two-dimensional nanomaterials of Ti2AlC were exfoliated in an acidic solution and then they were added into the sample solution. To enhance the sample solution and sorbent contact area, the mixture was vortexed for a few minutes. Then the adsorbed analytes onto the sorbent were eluted using acetone and then analyzed. Under optimal conditions, the calibration curves of the method were linear within the range of 3.0-1000 µg L-1. The limits of detection, intra- and inter-day relative standard deviations, and extraction recoveries were in the ranges of 0.08-1.0 µg L-1, 2.5-4.2%, 2.5-5.5%, and 69-75%, respectively. Performing the method verified the presence of some of the analytes in several samples. This method can help to monitor pesticides in juice samples as well as to improve our understanding the safety of foods.

Rapid photodegradation and detection of zolpidem over ß-SnWO4 and α-SnWO4 nanoparticles: optimization and mechanism.

We reported the tin (II) tungstate nanoparticles as the photocatalyst and sensor modifier that were synthesized via chemical precipitation reaction and optimized thru the Taguchi design method. The method predicted the best synthesis conditions that led to smaller particles and desired morphologies. Different techniques were used to characterize the chemical structure, morphology, and purity of the nanoparticles. The photocatalytic behavior of different crystalline forms of the SnWO4 nanoparticles (α and ß) was considered by photodegradation of methylene orange and zolpidem under UV light irradiation, while the average size of ß-SnWO4 and α-SnWO4 nanoparticles prepared in optimum conditions is about 17 nm and 20 nm, respectively. Efficiencies of degradation of methyl orange and zolpidem on ß-SnWO4, in the presence of UV irradiation, were 93% and 98% and in the presence of α-SnWO4 were 73% and 82% after 2100 s, respectively. Voltammetric sensing of zolpidem was designed by modification of carbon paste electrode via ß-SnWO4 nanoparticles and investigated for determination of the drug in aqueous solution.

A noble electrochemical sensor based on TiO2@CuO-N-rGO and poly (L-cysteine) nanocomposite applicable for trace analysis of flunitrazepam.

Flunitrazepam or date rape medication with trade name of Rohypnol belongs to the benzodiazepines branch that is used as a sedative, anesthetic, anticonvulsant, muscle relaxant, and antianxiety drug. It is known as "drug of aggression" because of its very strong and long-lasting effects on the central nervous system. The sedative influence of flunitrazepam drug increases with alcohol drinking, which causes mental and motor disorders and causes the victim to become silent. Due to its criminals use, its accurate measurement is crucial. In this work, a novel electrochemical sensor based on TiO2@CuO-N doped rGO, TiO2@CuO-N-rGO, nano-composite and poly (L-cysteine), poly (L-Cys), is presented for trace analysis of flunitrazepam in aqueous solution. At first, TiO2@CuO-N-rGO nano-composite was synthesized by the sol-gel method and characterized by Raman spectroscopy, Fourier transform infrared, field emission scanning electron microscope, and X-ray diffraction analysis. Then, the suspension of the TiO2@CuO-N-rGO nano-composite was drop casted on the surface of the glassy carbon electrode (GCE/TiO2@CuO-N-rGO). After that, electro-polymerization of l-cysteine on the GCE/TiO2@CuO-N-rGO surface was performed by cyclic voltammetry (CV) method. The electrochemical characteristics of the GCE/TiO2@CuO-N-rGO/poly (L-Cys) surface were evaluated in the solution of ferri/ferrocyanide by electrochemical impedance spectroscopy (EIS) and CV techniques. The increase in current, change in oxidation peak potential, and the appearance of two reduction peaks indicated higher electron transfer rate with well-performed electrochemical process of flunitrazepam at the modified electrode surface compared to the bare GCE. These improvements originate from the synergistic effect of TiO2@CuO-N-rGO nano-composite and poly (L-Cys). Finally, a linear relationship was resulted between the oxidation peak current and the concentration of flunitrazepam in the wide concentration range of 1 nM to 50 µM with a detection limit of 0.3 nM.

Stöber synthesis of salen-formaldehyde resin polymer- and carbon spheres with high nitrogen content and application of the corresponding Mn-containing carbon spheres as efficient electrocatalysts for the oxygen reduction reaction.

Salen-formaldehyde (SF) resin polymer spheres were synthesized by the Stöber method from 4,4'-dihydroxysalen (N,N'-bis-(4-hydroxysalicylidene)-ethylenediamine; a tetradentate N2O2 Schiff base ligand) and formaldehyde. The salen precursor was prepared by condensation of ethylenediamine with 2,4-dihydroxybenzaldehyde in methanol. The SF resin colloidal spheres were also prepared by using Pluronic F127 and ammonia as a porogenic agent and catalyst, respectively (SF-P). In addition, corresponding Mn(ii)-coordinated polymer spheres of the SF-P were synthesized (SF-P-Mn(ii)). Corresponding monodispersed carbon spheres of all of the abovementioned samples were also obtained by pyrolysis technique. All of the products were characterized with conventional microscopic and spectroscopic techniques, as well as other physical methods such as BET analysis. It was found that carbonization of the SF resin spheres results in carbon spheres with specific surface areas in the range of 499-528 m2 g-1 and average pore sizes in the range of 2.58-3.08 nm. Nitrogen content of the SF-MWHT (obtained hydrothermally in a methanol/water mixture), and SF-P-C@Mn (obtained from carbonization of SF-P-Mn(ii)) samples were as high as 27.5 wt% and 35.02 wt%, respectively. Finally, a glassy carbon electrode (GCE) modified with SF-P-C@Mn (SF-P-C@Mn/GCE) was prepared and its electrocatalytic activity was evaluated for oxygen reduction reaction (ORR) by linear sweep voltammetry (LSV). The LSV results showed that the SF-P-C@Mn/GCE has a higher current density and a lower negative potential in the ORR compared to GCE.

Electrochemical Oxidation and Determination of Antiviral Drug Acyclovir by Modified Carbon Paste Electrode With Magnetic CdO Nanoparticles.

With the development of nanomaterials in electrochemical sensors, the use of nanostructures to modify the electrode surface has been shown to improve the kinetics of the electron transfer process. In this study, a sensor was developed for the electrochemical determination of Acyclovir (ACV) based on the modified carbon paste electrode (CPE) by CdO/Fe3O4. The magnetic CdO nanoparticles characterization was studied by energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). To study of the modified CPE surface morphology, scanning electron microscopy (SEM) was used. At the optimal conditions, a noteworthy enhancement in the electrochemical behavior of ACV was observed at the surface of the modified CPE compared to the unmodified CPE. A detection limit of 300 nM and a linear range of 1-100 µM were obtained for the quantitative monitoring of ACV at the modified CPE surface using differential pulse voltammetry (DPV) in phosphate buffer. The RSD% (relative standard deviation) of the electrode response was <4.3% indicating the development of a high precision method. Also, satisfactory results were obtained in the determination of ACV with the modified electrode in tablet, blood serum, and urine samples with a satisfactory relative recovery (RR%) in the range of 94.0-104.4%.

A glassy carbon electrode modified with carbon nanoonions for electrochemical determination of fentanyl.

Fentanyl is a pain reliever stronger and deadlier than heroin. This lethal drug has killed many people in different countries recently. Due to the importance of the diagnosis of this drug, a fentanyl electrochemical sensor is developed based on a glassy carbon electrode (GCE) modified with the carbon nanoonions (CNOs) in this study. Accordingly, the electrochemical studies indicated the sensor is capable of the voltammetric determination of traces of fentanyl at a working potential of 0.85 (vs. Ag/AgCl). To obtain the great efficiency of the sensor some experimental factors such as time, the potential of accumulation and pH value of the electrolyte were optimized. The results illustrated a reduction and two oxidation peaks for fentanyl in phosphate buffer (PB) with pH = 7.0 under a probable mechanism of electrochemical-chemical-electrochemical (ECE). The differential pulse voltammetry (DPV) currents related to the fentanyl detection were linear with an increase of fentanyl concentrations in a linear range between 1 µM to 60 µM with a detection limit (LOD) of 300 nM. Furthermore, the values of the diffusion coefficient (D), transfer coefficient (α) and catalytic constant rate (kcat) were calculated to be 2.76 × 10-6 cm2 s-1, 0.54 and 1.76 × 104 M-1 s-1, respectively. These satisfactory results may be attributed to utilizing the CNOs in the electrode modification process due to some of its admirable characterizations of this nanostructure including high surface area, excellent electrical conductivity and good electrocatalytic activity. Consequently, these finding points the achieving a simple sensing system to measure of the fentanyl as an important drug from the judicial perspective might be a dream coming true soon.

Preparation of Fe3O4/SiO2/TiO2/CeVO4 Nanocomposites: Investigation of Photocatalytic Effects on Organic Pollutants, Bacterial Environments, and New Potential Therapeutic Candidate Against Cancer Cells.

The new nanocomposite with various molar ratios along with magnetic properties was fabricated via precipitation (assisted by ultrasonic) procedure. The photocatalytic effects of methylene blue (∼90% degradation for optimized sample in 100 min) for finding the optimized sample performed under visible light irradiation. Moreover, the photo-antibacterial impacts of bacteria culture environments were found with an optimized sample that had effective destruction of bacteria in comparison to control group. The cytotoxicity properties of panc1 cells and magnetic behaviors of the obtained nanomaterials were evaluated and its IC50 was about 500 mg/L. As an initial step, the structural, morphological and magnetic characteristics of the fabricated nanocomposites were evaluated by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and MAP, UV-visible diffuse reflectance spectroscopy (DRS), and vibrating sample magnetometry (VSM) approaches. Based on SEM results, the size of nanoparticles in fabricated nanocomposite was nearly 50-70 nm for Fe3O4/SiO2/TiO2 and 80-100 nm for Fe3O4/SiO2/TiO2/CeVO4. XRD results showed that desired nanocomposites were truly synthesized without any impurities.