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1.
Sci Rep ; 14(1): 7576, 2024 03 30.
Article in English | MEDLINE | ID: mdl-38555408

ABSTRACT

In this study, we aimed to enhance and accelerate the electrochemical properties of a glassy carbon-based voltammetric sensor electrode. This was achieved through the modification of the electrode using a nanocomposite derived from a metal-organic framework, which was embedded onto a substrate consisting of metal oxide nanoparticles. The final product was an electrocatalyst denoted as NiO/Ni@C-Fe3O4/CeO2, tailored for the detection of the drug niclosamide. Several techniques, including FT-IR, XRD, XPS, FE-SEM, TEM, and EDS, were employed to characterize the structure and morphology of this newly formed electroactive catalyst. Subsequently, the efficiency of this electrocatalyst was evaluated using cyclic voltammetry and electrochemical impedance spectroscopy techniques. Differential pulse voltammetry was also utilized to achieve heightened sensitivity and selectivity. A comprehensive exploration of key factors such as the catalyst quantity, optimal instrumental parameters, scan rate influence, and pH effect was undertaken, revealing a well-regulated reaction process. Furthermore, the sensor's analytical performance parameters were determined. This included establishing the linear detection range for the target compound within a specified concentration interval of 2.92 nM to 4.97 µM. The detection limit of 0.91 nM, repeatability of 3.1%, and reproducibility of 4.8% of the sensor were calculated, leading to the observation of favorable stability characteristics. Conclusively, the developed electrochemical sensor was successfully employed for the quantification of niclosamide in urine samples and niclosamide tablets. This application highlighted not only the sensor's high selectivity but also the satisfactory and accurate outcomes obtained from these measurements.


Subject(s)
Metal Nanoparticles , Niclosamide , Reproducibility of Results , Spectroscopy, Fourier Transform Infrared , Carbon/chemistry , Oxides , Electrochemical Techniques/methods , Electrodes
3.
Bioelectrochemistry ; 156: 108621, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38042068

ABSTRACT

In this study, we investigated the binding mode between double-stranded deoxyribonucleic acid (dsDNA) and curcumin (CU) using differential pulse voltammetry (DPV), UV-Vis spectroscopy, and molecular docking. By employing these techniques, we predicted the binding within the minor groove region of dsDNA and CU. Significantly, we employed electrochemistry, specifically cyclic voltammetry (CV), to explore the temperature effect on the dsDNA and CU binding. To the best of our knowledge, this is the first study to utilize electrochemical methods for investigating the temperature-dependent behavior of this binding interaction. Our findings revealed temperature-dependent variations in the binding constants: 2.42 × 103 M-1 at 25 °C, 4.26 × 103 M-1 at 30 °C, 5.44 × 103 M-1 at 35 °C, 6.29 × 103 M-1 at 40 °C, and 7.52 × 103 M-1 at 45 °C. Notably, the binding constant exhibited an increasing trend with elevated temperatures, indicating a temperature-dependent enhancement of the binding interaction.


Subject(s)
Curcumin , Temperature , Molecular Docking Simulation , DNA/chemistry , Electrodes
4.
Sci Rep ; 13(1): 19772, 2023 Nov 13.
Article in English | MEDLINE | ID: mdl-37957225

ABSTRACT

Flexible electrodes with high deformability and energy density are critical for electronic textiles. The key factor for achieving high-performance supercapacitors with superior power and energy density is the evaluation of materials that exhibit exceptional capacitive performance. Herein, we have prepared Ni-Co nanoparticles at the surface of polyaniline-salphen (Ni-Co@PS). Then, followed by casting Ni-Co@PS on a conductive carbon cloth (CC) as a substrate through a facile in-situ polymerization strategy. The morphologies of Ni-Co@PS composite were characterized by different methods such as FE-SEM, XPS, XRD, BET, and electrochemical methods. This nanocomposite showed high tolerability and a large surface area with excellent behavior as a new nanomaterial for supercapacitor application. Thus, the optimum composite designed with a metal ratio (nickel-cobalt 3:1 w/w) satisfactorily possesses a specific capacitance of up to 549.994 C g-1 (1447.2 F g-1) under 0.5 A g-1 and long-term cyclic stability featuring capacity retention of 95.9% after 5000 cycles at a current density of 9.0 A g-1. The Ni-Co@PS-CC, is a material with great potential as an electrode in asymmetric wearable supercapacitor (AWSC) apparatus, demonstrating a remarkable specific capacity of 70.01, and accompanied by an energy density of 23.46 Wh k g-1 at a power density of 800 W k g-1.

5.
Sci Rep ; 13(1): 12422, 2023 Aug 01.
Article in English | MEDLINE | ID: mdl-37528177

ABSTRACT

In this study, we conducted direct synthesis of a dual metal-organic framework (Ni/Co-Hemin MOF) on phosphorous-doped reduced graphene oxide (PrGO) to serve as an active material in high-performance asymmetrical supercapacitors. The nanocomposite was utilized as an active material in supercapacitors, exhibiting a noteworthy specific capacitance of 963 C g-1 at 1.0 A g-1, along with a high rate capability of 68.3% upon increasing the current density by 20 times, and superior cycling stability. Our comprehensive characterization and control experiments indicated that the improved performance can be attributed to the combined effect of the dual MOF and the presence of phosphorous, influencing the battery-type supercapacitor behavior of GO. Additionally, we fabricated an asymmetric hybrid supercapacitor (AHSC) using Ni/Co-Hemin/PrGO/Nickel foam (NF) and activated carbon (AC)/NF. This AHSC demonstrated a specific capacitance of 281 C g-1 at 1.0 A g-1, an operating voltage of 1.80 V, an impressive energy density of 70.3 Wh kg-1 at a high power density of 0.9 kW kg-1. Notably, three AHSC devices connected in series successfully powered a clock for approximately 42 min. These findings highlight the potential application of Hemin-based MOFs in advanced supercapacitor systems.

6.
ACS Sens ; 8(5): 1891-1900, 2023 05 26.
Article in English | MEDLINE | ID: mdl-36877535

ABSTRACT

With the development of drug delivery systems, the use of nanomaterials for slow, targeted, and effective drug release has grown significantly. To ensure the quality of performance, it is essential to obtain drug release profiles from therapeutic nanoparticles prior to in vivo testing. Typically, the methods of monitoring the drug release profile from nanoparticle drug delivery systems include one or more filtration, separation, and sampling steps, with or without membrane, which cause several systematic errors and make the process time-consuming. Here, the release rate of doxorubicin as a model drug from liposome as a nanocarrier was determined via highly selective binding of released doxorubicin to the doxorubicin-imprinted electropolymerized polypyrrole as a molecularly imprinted polymer (MIP). Incubation of the MIP-modified substrate with imprinted cavities complementary to doxorubicin molecules in the releasing medium leads to the binding of released doxorubicin molecules to cavities. The drug trapped in the cavities is determined by one of the analytical methods depending on its signaling properties. In this work, due to the favorable electrochemical properties of doxorubicin, the voltammetry method was used for quantitative analysis of released doxorubicin. The voltammetric oxidation peak current intensity of doxorubicin on the surface of the electrode was enhanced by increasing the release time. This membranelle platform allows fast, reliable, and simple monitoring of drug release profiles without any sample preparation, filtration, and centrifugation in buffer and blood serum samples.


Subject(s)
Molecular Imprinting , Polymers , Polymers/chemistry , Molecularly Imprinted Polymers , Molecular Imprinting/methods , Drug Liberation , Electrochemical Techniques/methods , Kinetics , Renal Dialysis , Pyrroles/chemistry , Centrifugation
7.
Sci Rep ; 13(1): 2070, 2023 Feb 06.
Article in English | MEDLINE | ID: mdl-36746977

ABSTRACT

The synergistic effect between metal ions and increasing the surface area leads to the fabrication of supercapacitor materials with high capacities. It is predicted that transition metal selenide compounds will be ideal electrode materials for supercapacitors. However, the defects of poor conductivity and volume expansion of the compounds are fundamental problems that must be solved. In this work, we successfully synthesized the cobalt-nickel selenide nitrogen-doped carbon (H-CoNiSe2/NC) hollow polyhedral composite structure using ZIF-67 as a precursor. The CoSe2 and NiSe2 nanoparticles embedded in the NC polyhedral framework offer a wealth of active sites for the whole electrode. Moreover, the presence of the NC structure in the proposed composite can simultaneously lead to improved conductivity and reduce the volume effect created during the cycling procedure. The H-CoNiSe2/NC electrode provides high specific capacity (1131 C/g at 1.0 A/g) and outstanding cyclic stability (90.2% retention after 6000 cycles). In addition, the H-CoNiSe2/NC//AC hybrid supercapacitor delivers ultrahigh energy density and power density (81.9 Wh/kg at 900 W/kg) and excellent cyclic stability (92.1% of the initial capacitance after 6000 cycles). This study will provide a supercapacitor electrode material with a high specific capacity for energy storage devices.Please confirm the corresponding affiliation for the 'Ali A. Ensafi' author is correctly identified.Error during converting author query response. Please check the eproofing link or feedback pdf for details.

8.
Sci Rep ; 13(1): 1364, 2023 Jan 24.
Article in English | MEDLINE | ID: mdl-36693890

ABSTRACT

The design of bimetallic tellurides that exhibit excellent electrochemical properties remains a huge challenge for high-performance supercapacitors. In the present study, tellurium is consolidated on CoNi2@rGO for the first time, to synthesize NiTe2-Co2Te2@rGO nanocomposite by using a facile hydrothermal method. As-prepared NiTe2-Co2Te2@rGO nanocomposite was characterized by EDS, TEM, FESEM, Raman, BET, XRD, and XPS techniques to prove the structural transformation. Upon the electrochemical characterization, NiTe2-Co2Te2@rGO has notably presented numerous active sites and enhanced contact sites with the electrolyte solution during the faradic reaction. The as-prepared nanocomposite reveals a specific capacity of 223.6 mAh g-1 in 1.0 M KOH at 1.0 A g-1. Besides, it could retain 89.3% stability after 3000 consecutive galvanostatic charge-discharge cycles at 1.0 A g-1 current density. The hybrid supercapacitor, fabricated by activated carbon as an anode site, and NiTe2-Co2Te2@rGO as a cathode site, presents a potential window of 1.60 V with an energy density of 51 Wh kg-1 and a power density of 800 W kg-1; this electrode is capable of lighting up two red LED lamps and a yellow LED lamp for 20 min, which is connected in parallel. The present work opens new avenues to design and fabrication of nanocomposite electrode materials in the field of supercapacitors.

9.
Anal Chem ; 94(46): 16033-16041, 2022 11 22.
Article in English | MEDLINE | ID: mdl-36350607

ABSTRACT

Electrochemical sensors for the dissolved CO2 (dCO2) measurement have attracted great interest because of their simple setup and the resulting low costs. However, the developed sensors suffer from the requirement of the external electrical power supply throughout the sensing. Here, the fabrication and evaluation of a self-powered biosensor based on biofuel cells (BFCs) for dCO2 measurements are described. In this device, AuNPs-multiwalled carbon nanotubes/GOx-modified carbon paper (CP) served as a bioanode for the oxidation of glucose, while imine-linked covalent triazine framework (I-CTF)-modified CP was employed as the cathode for the reduction of Fe(CN)63-. I-CTF is a porous organic polymer with a high CO2 capture capacity. Voltammetry and electrochemical impedance spectroscopy confirmed that the electron transfer of Fe(CN)63- on the I-CTF-modified electrode decreases after contacting I-CTF with dCO2. In the designed BFC, by capturing CO2 by the I-CTF-modified cathode, a significant decrease in open-circuit voltage (EOCV) of the BFC was observed, which can be used for the sensitive measurement of dCO2. In addition to the self-powering feature, the EOCV of the BFC sensor can be restored when the captured CO2 is desorbed from the I-CTF-modified cathode by increasing the temperature of the cathode. Finally, the BFC is integrated into a circuit containing a matching capacitor; the charges generated by the BFC are accumulated on the capacitor, and then the instantaneous current is quickly detected using a switching regulator and a digital multimeter. Under optimal conditions, the instantaneous current of the BFC sensor was found to sensitively respond to dCO2 in a wide concentration range from 1.3 × 10-5 to 0.252 atm with a low detection limit of 5 × 10-6 atm.


Subject(s)
Bioelectric Energy Sources , Biosensing Techniques , Metal Nanoparticles , Nanotubes, Carbon , Carbon Dioxide , Gold , Electrodes , Biosensing Techniques/methods , Biological Assay
10.
J Pharm Biomed Anal ; 221: 115026, 2022 Nov 30.
Article in English | MEDLINE | ID: mdl-36113325

ABSTRACT

Metal-organic framework (MOF) materials provide unprecedented opportunities for evaluating valuable compounds for various medical applications. MOFs merged with biomolecules, used as novel biomaterials, have become particularly useful in biological environments. Bio-MOFs can be promising materials in the global to avoid utilization above toxicological substances. Bio-MOFs with crystallin and porosity nature offer flexible structure via bio-linker and metal node variation, which improves their wide applicability in medical science.


Subject(s)
Crystallins , Metal-Organic Frameworks , Biocompatible Materials/chemistry , Metal-Organic Frameworks/chemistry , Pharmaceutical Preparations , Porosity
11.
Chemosphere ; 303(Pt 3): 135149, 2022 Sep.
Article in English | MEDLINE | ID: mdl-35660395

ABSTRACT

Due to its toxicological and pharmacological activity, the misuse and overuse of morphine (MO), codeine (CO), and heroine have attracted attention in the medical and forensic toxicology fields. This study proposed a new electrochemical sensor with an acceptable detection limit, linear range, and selectivity for simultaneous determination of MO and CO. This sensor is based on Cu-Hemin metal-organic framework (CHM) and multiwall carbon nanotubes (MWCNTs). First, a facile chemical method was chosen to synthesize CHM and then composite it with MWCNTs. Afterward, the structure of CHM@MWCNTs was verified by XRD, FT-IR, Raman spectroscopy, UV-vis, ICP-OES, FE-SEM, EDX, and elemental mapping. In the next step, under optimal conditions, this electrochemical sensor can sensitive simultaneous determination of MO and CO, showing a dynamic concentration range from 0.09 to 30 µM for both species and a low detection limit of 9.2 nM and 11.2 nM for MO and CO, respectively. Moreover, the applicability in real samples was confirmed by the simultaneous determination of MO and CO in human urine and MO injection. This work reveals a trustable sensor based on MOF and MWCNTs to simultaneously determine opioid drugs in clinical application.


Subject(s)
Nanotubes, Carbon , Analgesics, Opioid , Electrochemical Techniques/methods , Hemin , Humans , Limit of Detection , Nanotubes, Carbon/chemistry , Spectroscopy, Fourier Transform Infrared
12.
Chemosphere ; 299: 134251, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35278455

ABSTRACT

Herein, a nanohybrid material containing graphene-like sheets (GS) and Fe-Co layered double hydroxides nanoflakes (LDHs) was synthesized via simple two-step processes and named Fe-Co LDHs/GS. The Fe-Co LDHs/GS nanohybrid was characterized by various techniques. Fe-Co LDHs nanoflakes were grown on GS in Fe-Co LDHs/GS nanohybrid. The electrochemical surface area of Fe-Co LDHs/GS nanohybrid was obtained 0.05 cm2 based on the Randles-Sevcik equation. The Fe-Co LDHs/GS nanohybrid was applied as an electrocatalyst of HER and OER in a 1.0 M KOH. The electrochemical performance of Fe-Co LDHs/GS nanohybrid was surveyed by several electrochemical methods, and long-term electrochemical stability. The onset potential, overpotential at 10 mA cm-1 current density, and Tafel slope for the Fe-Co LDHs/GS nanohybrid were obtained -0.33 V, -0.43 V (vs. RHE), and 122 mV dec-1, respectively. The Fe-Co LDHs/GS nanohybrid has long-term stability over 35 h in alkaline media toward HER. Furthermore, the onset potential, overpotential at 10 mA/cm, and Tafel slope for the Fe-Co LDHs/GS nanohybrid were obtained as 1.52 V, 1.60 V (vs. RHE), and 44 mV dec-1, respectively. The Fe-Co LDHs/GS nanohybrid has long-term durability over 10 h in alkaline media toward OER.

13.
Chemosphere ; 294: 133670, 2022 May.
Article in English | MEDLINE | ID: mdl-35066081

ABSTRACT

In-situ designing of multiple metals electrocatalysts with high active sites and performance is the main challenge for hydrogen evolution reaction (HER). So in this work, 3D-rGO was easily obtained from 2D-graphene by a simple one-step hydrothermal method to create the interspace sites and active surface area. The Ni-Co-Mo tri-metallic@3D-rGO was synthesized and fully characterized by different techniques, e.g., FT-IR, XRD, Raman, FE-SEM, TEM, EDS, mapping, ICP-OES, AFM, voltammetry, and electrochemical impedance spectroscopy. According to the FE-SEM and TEM images, the Ni-Co-Mo tri-metallic@3D-rGO has a crumpled-formed structure. The as-prepared nanocomposite has high HER performance with a low potential of -0.11 (vs. RHE) to deliver 10 mA cm-2 and Tafel slope of 68 mV dec-1 for Pt and -0.25 V (vs. RHE) to deliver 10 mA cm-2 and Tafel slope of 110 mV dec-1 for graphite counter electrode. Furthermore, the 3D structure illustrates high long-term durability in the HER process for 1000 continuous cycles and 12 h operation at -0.42 V (vs. RHE) for Pt and graphite counter electrode. It's noticeable HER performance has the synergetic effect between 3D-rGO and tri-metallic structure with high porosity and electrical conductivity, enhancing HER kinetic.


Subject(s)
Graphite , Nanocomposites , Cobalt , Graphite/chemistry , Hydrogen/chemistry , Molybdenum/chemistry , Nanocomposites/chemistry , Nickel , Spectroscopy, Fourier Transform Infrared
14.
Chemosphere ; 292: 133460, 2022 Apr.
Article in English | MEDLINE | ID: mdl-34971631

ABSTRACT

An electrochemical aptasensor has been developed to determine K+ using electrochemical impedance spectroscopy. The polyaniline (PANI) coating was first electrodeposited on a GCE. Then, the potassium-selective aptamer [G3(T2AG3)3] was adsorbed through an electrostatic force between PANI and aptamer. In the presence of K+, the single-stranded DNA is folded into the G-quadruplex configuration, which acts as a barrier against electron transfer at the GCE surface. AFM and FE-SEM images characterize the surface morphology at each fabrication stage. As the K+ concentration increased, the charge transfer resistance (Rct) increased, and the plot of ΔRct versus the logarithm of the K+ concentration is linear over a wide range of 10 pM-60 µM with a low detection limit of 3.7 pM. Finally, the proposed sensor was used to determine K+ in water, serum, urine, and fruit samples. Moreover, the binding stability of the aptamer/PANI and K+/Aptamer/PANI and the interactions between the aptamer and PANI were analyzed through molecular dynamics simulation.


Subject(s)
Biosensing Techniques , Aniline Compounds , DNA, Single-Stranded , Electrochemical Techniques , Electrodes , Ions , Potassium
15.
Anal Bioanal Chem ; 413(30): 7451-7462, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34668997

ABSTRACT

This work introduces an electrochemical aptasensor based on a single-stranded aptamer-Au@Fe-MIL-88 complex for sensitive and selective determination of insulin using differential pulls voltammetry. Au@Fe-MIL-88 with a large surface area was synthesized and employed as a suitable substrate for immobilization of the aptamer (APT-Au@Fe-MIL-88). Methylene blue (MB), as an electrochemical probe, was intercalated into the aptamer. Graphene oxide (GO) and zinc sulfide (ZnS) were placed on the Au electrode to amplify the MB current. Also, ZnS improves the immobilization of APT-Au@Fe-MIL-88 into the aptasensor through the strong interaction of Au-S. In the presence of the insulin, MB is released from the aptamer due to DNA conformational change, and as a result, the peak intensity of the intercalated MB was decreased. Under optimal conditions, the change in the current of MB was proportional to the insulin concentration in the range of 5.0 × 10-16-5.0 × 10-11 mol L-1, with a superior ultra-low detection limit of 1.3 × 10-16 mol L-1. It was observed that the aptasensor is suitable for determining insulin in serum samples with good sensitivity and reproducibility and with recoveries ranging from 96.4 to 102.0%. The relative standard deviations (RSD) were lower than 3.8% (n = 3).


Subject(s)
Aptamers, Nucleotide/chemistry , Electrochemical Techniques/methods , Gold/chemistry , Insulin/blood , Iron/chemistry , Metal-Organic Frameworks/chemistry , Methylene Blue/chemistry , Molecular Probes/chemistry , DNA, Single-Stranded/chemistry , Humans , Limit of Detection , Reproducibility of Results , Spectrum Analysis/methods
16.
Mikrochim Acta ; 188(1): 1, 2021 01 02.
Article in English | MEDLINE | ID: mdl-33386503

ABSTRACT

Polymelamine formaldehyde/graphene oxide (PMF/GO) nanocomposite was used, for the first time, to study the ultrasensitive and selective electrochemical detection of oxycodone (OXC). The successful characterization of PMF/GO was verified based on scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and Raman spectroscopy. The modified GCE (PMF/GO-GCE) proved its electrocatalytic effect on OXC determination according to cyclic, linear sweep, and differential pulse voltammetry (CV, LSV, and DPV) and electrochemical impedance spectroscopy (EIS) studies. The developed sensor under optimal conditions offered a linear relationship in a limited range of  0.01 to 45 µmol L-1 with the limit of detection (LOD) of 2.0 nmol L-1. The proposed PMF/GO-GCE sensor was effectively employed for the OXC detection in human urine and serum samples. Graphical abstract.


Subject(s)
Graphite/chemistry , Nanocomposites/chemistry , Oxycodone/blood , Oxycodone/urine , Polymers/chemistry , Triazines/chemistry , Carbon/chemistry , Electrochemical Techniques/instrumentation , Electrochemical Techniques/methods , Electrodes , Humans , Limit of Detection , Oxidation-Reduction , Oxycodone/chemistry , Reproducibility of Results
17.
Food Chem ; 339: 127920, 2021 Mar 01.
Article in English | MEDLINE | ID: mdl-32877812

ABSTRACT

Rapid and efficient detection of indoxacarb (IXC), a common chemical contaminant, in environmental and biological samples is necessary. In this work, a modern optical sensor was developed for IXC, based on environmentally friendly molecularly imprinted polymer (MIP) coated on silica-carbon quantum dots (SiCQDs). A hydrothermal method was used to prepare highly fluorescence SiCQDs and, subsequently, MIP formed on surface (MIP@SiCQDs) using a sol-gel method. A linear relationship between the fluorescence quenching effect and increased IXC concentration was found for the range of 4-102 nM, under the optimal conditions, with a 1 nM detection limit. Precisions was of 4.5 and 2.3% for five replicate detections at 21 and 60 nM IXC, respectively. Applicability of the sensor for IXC quantification in environmental and biological samples was verified with recoveries in the range 95-106% with a relative standard deviation of <6.0%.


Subject(s)
Oxazines/analysis , Quantum Dots/chemistry , Carbon/chemistry , Hydrogen-Ion Concentration , Limit of Detection , Molecularly Imprinted Polymers/chemistry , Reproducibility of Results , Silicon Dioxide/chemistry , Spectrometry, Fluorescence , Temperature
18.
Anal Methods ; 12(43): 5210-5218, 2020 11 21.
Article in English | MEDLINE | ID: mdl-33078768

ABSTRACT

In the present work, to enhance the properties of a pencil graphite electrode (PGE), highly functionalized carbon quantum dots (CQDs) were synthesized and mixed with multiwall carbon nanotubes (MWCNTs) as novel modifiers for the preparation of working electrodes. These modifiers exhibited unique characteristics owing to the fascinating and well-defined properties of the CQD-MWCNT nanocomposite, including high surface to volume ratio, high conductivity, high stability and excellent electrocatalytic activity. Consequently, a modified pencil graphite electrode based on poly (diallyldimethylammonium chloride) (PDDA)/MWCNT/CQD was used to monitor the oxidation signals of methadone hydrochloride. Notably, field emission scanning electron microscopy (FE-SEM) was used to characterize the morphology and features of the different modifiers on the electrode surface. The proposed sensor was characterized via electrochemical studies including differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under the optimum experimental conditions, the current response and concentration of methadone exhibited a linear relationship in the range of 0.1-225 µM with a detection limit of 0.03 µM. Furthermore, this sensor was successfully applied to determine methadone in human urine and plasma samples.


Subject(s)
Nanotubes, Carbon , Quantum Dots , Electrochemical Techniques , Electrodes , Humans , Limit of Detection , Methadone
19.
J Food Sci Technol ; 57(12): 4697-4706, 2020 Dec.
Article in English | MEDLINE | ID: mdl-33087980

ABSTRACT

ABSTRACT: This study dealt with the fabrication of an impedimetric biosensor based on nanomaterial modified with pencil graphite electrode for the detection of tetracycline (TET) in milk samples. For response of the impedimetric aptasensor to be improved, the influence of different parameters (immobilization time of reduced grapheme oxide, time of aptamer, and TET binding, and concentration of aptamer) was optimized. In optimum conditions, the aptasensor provided a concentration range within 1 × 10-16 - 1 × 10-6 M and with a limit of detection of 3 × 10-17 M TET. The proposed impedimetric aptasensor was then used in milk samples analysis, and the acceptable recovery was achieved ranging from 92.8 to 102.1%. According to this study, the combination of an aptamer and electrochemical impedance spectroscopy is a promising method for detection of TET in milk samples with high reproducibility and stability.

20.
Anal Chim Acta ; 1111: 92-102, 2020 May 15.
Article in English | MEDLINE | ID: mdl-32312402

ABSTRACT

Polluted water and groundwater resources contaminated by pesticides are among the most important environmental distresses. Therefore, a simple, ultrasensitive, and selective electrochemical aptasensor is proposed for diazinon (DZN) determination as an organophosphorus compound. The vanadium disulfide quantum dots (VS2QDs) were synthesized by a facile hydrothermal method and doped on the graphene nanoplatelets/carboxylated multiwalled carbon nanotubes (GNP/CMWCNTs) as a new group of nanocomposite. The prepared nanocomposite (VS2QDs-GNP/CMWCNTs) on a glassy carbon electrode (GCE) was incubated with the DZN binding aptamer (DZBA) through electrostatic interaction (GCE/VS2QDs-GNP/CMWCNTs/DZBA). The modified electrode was used for the low detection of DZN by monitoring the oxidation of [Fe(CN)6]3-/4- as the redox probe. The characterizations of the modified electrode were performed by several electrochemical methods include: cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Also, the prepared nanocomposite was characterized with field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), UV-Vis absorption spectroscopy, fourier transform infrared (FT-IR), fluorescence emission spectroscopy, dynamic light scattering (DLS), elemental mapping, and energy dispersive spectroscopy (EDS). The DZBA selectively adsorbs DZN on the modified electrode, leading to a decrease and increase in the current of DPV and charge transfer resistance (RCT) of EIS, respectively, as analytical signals. The developed electrochemical aptasensor at the optimal conditions have low limits of detection (LOD) equal to 1.1 × 10-14 and 2.0 × 10-15 mol L-1 with wide dynamic ranges of 5.0 × 10-14-1.0 × 10-8 mol L-1 and 1.0 × 10-14-1.0 × 10-8 mol L-1 for DPV and EIS calibration curves, respectively. Finally, this aptasensor had good selectivity, stability, reproducibility, and feasibility for the DZN detection in various real samples.

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