Characterization of carbon nanotubes decorated with NiFe2O4 magnetic nanoparticles as a novel electrochemical sensor: application for highly selective determination of sotalol using voltammetry.

A magnetic nano-composite of multiwall carbon nanotube, decorated with NiFe2O4 nanoparticles, was synthesized with citrate sol-gel method. The multiwall carbon nanotubes decorated with NiFe2O4 nanoparticles (NiFe2O4-MWCNTs) were characterized with different methods such as Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The new nano-composite acts as a suitable electrocatalyst for the oxidation of sotalol at a potential of 500 mV at the surface of the modified electrode. Linear sweep voltammetry exhibited two wide linear dynamic ranges of 0.5-1000 μmol L(-1) sotalol with a detection limit of 0.09 μmol L(-1). The modified electrode was used as a novel electrochemical sensor for the determination of sotalol in real samples such as pharmaceutical, patient and safe human urine.

Ensafi AA ，Allafchian AR ，Rezaei B ，Mohammadzadeh R ... -  《-》

Multiwall carbon nanotubes decorated with NiFe2O4 magnetic nanoparticles, a new catalyst for voltammetric determination of cefixime.

Multiwall carbon nanotubes were decorated with synthesized NiFe(2)O(4) magnetic nanoparticles. The new materials were characterized with different techniques such as transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy and electrochemical impedance spectroscopy. The multiwall carbon nanotubes decorated with NiFe(2)O(4) magnetic nanoparticles was used as a new mediator for the voltammetric determination of cefixime. Under the optimum conditions at pH 8.0, the oxidation of cefixime was occurred at 850 mV at the surface of the modified electrode. Linear sweep voltammetry exhibited two wide linear dynamic ranges of 0.1-100 and 100-600 μmol L(-1) cefixime. The detection limit was found to be 0.02 μmol L(-1) cefixime. Finally, the modified electrode showed good sensitivity, selectivity and stability for the determination of cefixime in real samples.

Ensafi AA ，Allafchian AR 《-》

A sensitive and selective voltammetric sensor based on multiwall carbon nanotubes decorated with MgCr₂O₄ for the determination of azithromycin.

In this report, we synthesized MgCr(2)O(4) nanoparticles and then multiwall carbon nanotubes were decorated with the MgCr(2)O(4) nanoparticles. The characteristics of the new materials were studied with different techniques such as transmission electron microscopy, Fourier transform infrared spectroscopy, atomic force microscopy and electrochemical impedance spectroscopy. The multiwall carbon nanotubes decorated with MgCr(2)O(4) nanoparticles were used as a new mediator for voltammetric determination of azithromycin. The oxidation peak of azithromycin was appeared at a potential of about 720 mV at a surface of the modified electrode. Differential pulse voltammetry exhibited two wide linear dynamic ranges of 0.25-4.0 and 4.0-10.0 μmol L(-1) azithromycin with a detection limit of 0.07 μmol L(-1) at pH 7.0. The influence of potential interfering compounds on the selectivity was studied. Finally, the modified electrode showed good sensitivity, selectivity and stability for the determination of azithromycin in real samples.

Ensafi AA ，Allafchian AR ，Rezaei B 《-》

The study of structural properties of carbon nanotubes decorated with NiFe₂O₄ nanoparticles and application of nano-composite thin film as H₂S gas sensor.

Nano-composite of multiwall carbon nanotube, decorated with NiFe2O4 nanoparticles (NiFe2O4-MWCNT), was synthesized using the sol-gel method. NiFe2O4-MWCNTs were characterized using different methods such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM). The average size of the crystallites is 23.93 nm. The values of the saturation magnetization (MS), coercivity (HC) and retentivity (MR) of NiFe2O4-MWCNTs are obtained as 15 emu g(-1), 21Oe and 5 emu g(-1), respectively. In this research, NiFe2O4-MWCNT thin films were prepared with the spin-coating method. These thin films were used as the H2S gas sensor. The results suggest the possibility of the utilization of NiFe2O4-MWCNT nano-composite, as the H2S detector. The sensor shows appropriate response towards 100 ppm of H2S at 300°C.

Hajihashemi R ，Rashidi AM ，Alaie M ，Mohammadzadeh R ，Izadi N ... -  《-》

Fabrication of a modified electrode based on Fe(3)O(4)NPs/MWCNT nanocomposite: application to simultaneous determination of guanine and adenine in DNA.

Multi-walled carbon nanotubes decorated with Fe(3)O(4) nanoparticles (Fe(3)O(4)NPs/MWCNT) were prepared and used to construct a novel biosensor for the simultaneous detection of adenine and guanine. The direct electro-oxidation of adenine and guanine on the modified electrode were investigated by linear sweep voltammetry. The results indicate a remarkable increase in the oxidation peak currents together with negative shift in the oxidation peak potentials for both adenine and guanine, in comparison to the bare glassy carbon electrode (GCE). The surface morphology and nature of the composite film deposited on GCE were characterized by transmission electron microscopy, atomic force microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The Fe(3)O(4)NPs/MWCNT based electrochemical biosensor exhibits linear ranges of 0.01-10 μM and 0.05-8 μM with detection limits of 1 nM and 5 nM for adenine and guanine, respectively. The proposed method was successfully applied for a highly sensitive simultaneous determination of trace amounts of adenine and guanine in DNA of fish sperm samples with satisfactory results. The experimental detection limit was found to be equal to 3 ng mL(-1) DNA. The value of (G+C)/(A+T) in DNA was calculated to be 0.81. The fabricated electrode showed excellent reproducibility, repeatability and stability.

Shahrokhian S ，Rastgar S ，Amini MK ，Adeli M ... -  《-》