A novel electrochemical sensor based on metal-organic framework for electro-catalytic oxidation of L-cysteine.

A novel electrochemical sensor based on Au-SH-SiO₂ nanoparticles supported on metal-organic framework (Au-SH-SiO₂@Cu-MOF) has been developed for electrocatalytic oxidation and determination of L-cysteine. The Au-SH-SiO₂@Cu-MOF was characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction and cyclic voltammetry. The electrochemical behavior of L-cysteine at the Au-SH-SiO₂@Cu-MOF was investigated by cyclic voltammetry. The Au-SH-SiO₂@Cu-MOF showed a very efficient electrocatalytic activity for the oxidation of L-cysteine in 0.1 M phosphate buffer solution (pH 5.0). The oxidation overpotentials of L-cysteine decreased significantly and their oxidation peak currents increased dramatically at Au-SH-SiO₂@Cu-MOF. The potential utility of the sensor was demonstrated by applying it to the analytical determination of L-cysteine concentration. The results showed that the electrocatalytic current increased linearly with the L-cysteine concentration in the range of 0.02-300 μM and the detection limit was 0.008 μM. Finally, the sensor was applied to determine L-cysteine in water and biological samples.

Hosseini H ，Ahmar H ，Dehghani A ，Bagheri A ，Tadjarodi A ，Fakhari AR ... -  《-》

A novel sensor of cysteine self-assembled monolayers over gold nanoparticles for the selective determination of epinephrine in presence of sodium dodecyl sulfate.

Atta NF ，Galal A ，El-Ads EH 《-》

Probing cysteine self-assembled monolayers over gold nanoparticles--towards selective electrochemical sensors.

Cysteine forms self-assembled monolayers over gold nanoparticles. Based on this knowledge, a novel electrochemical sensor (Au-Au(nano)-Cys-SDS) has been constructed by the formation of self-assembly monolayer (SAM) of cysteine on gold-nanoparticles modified gold electrode (Au-Au(nano)-Cys) to be utilized for determination of dopamine in the presence of sodium dodecyl sulfate (SDS). Electrochemical investigation and characterization of the modified electrode sensor was achieved using cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron, and atomic force microscopies. Au-Au(nano)-Cys electrode in the presence of SDS gave comparable high current response to that of the gold nanoparticles modified gold electrode (Au-Au(nano)). The Au-Au(nano)-Cys-SDS electrode current signal was remarkably stable via repeated cycles and long term stability due to the strong AuS bond. Very small peak separation, almost zero or 15 mV peak separation was also obtained by repeated cycles indicating unusual high reversibility. The oxidation peak current was determined to be linearly dependent on the dopamine concentration. A resulting calibration curve using square wave voltammetry (SWV) was obtained over concentration range of 30-100 μmol L(-1) and 120-320 μmol L(-1) with correlation coefficients of 0.996 and 0.994 and a limit of detection of 16 and 57 nmol L(-1), respectively. Using differential pulse voltammetry (DPV), a highly selective and simultaneous determination of tertiary mixture of ascorbic acid AA, dopamine, and acetaminophen APAP was explored at this modified electrode. It has been demonstrated that Au-Au(nano)-Cys-SDS electrode can be used as a sensor with excellent reproducibility, sensitivity, and long term stability.

Galal A ，Atta NF ，El-Ads EH 《-》

Ordered carbohydrate-derived porous carbons immobilized gold nanoparticles as a new electrode material for electrocatalytical oxidation and determination of nicotinamide adenine dinucleotide.

The ordered carbohydrate-derived porous carbons (OC-DPCs) were first functionalized with thiol groups (-SH) and then immobilized with gold nanoparticles (AuNPs). The Au-SH-OC-DPCs were characterized by CHN analysis, transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD). The Au-SH-OC-DPCs were applied for the fabrication of a new electrochemical sensor. The electrocatalytic capabilities of the new sensor were tested by the oxidation of nicotinamide adenine dinucleotide (NADH) in a 0.1 M Robinson buffer solution (pH 7.0) using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and differential pulse voltammetry (DPV). The Au-SH-OC-DPCs showed a good voltammetric performance in the electrochemical detection of NADH with a low detection limit (1.0 nM), high sensitivity (4.934 μA/μM), and wide linear concentration range (5.0 nM-10 µM).

Hosseini H ，Behbahani M ，Mahyari M ，Kazerooni H ，Bagheri A ，Shaabani A ... -  《-》

Investigation of the electrochemical and electrocatalytic behavior of positively charged gold nanoparticle and L-cysteine film on an Au electrode.

Zhang L ，Yuan R ，Chai Y ，Li X ... -  《-》