Horseradish peroxidase (HRP) and toluidine blue (TB) were incorporated in polyion complex membrane composed of double stranded DNA(dsDNA) and chitosan prepared on the surface of an glassy carbon (GC) disk electrode to fabricate highly sensitive and selective reagentless H2O2 biosensor. The embedded-TB in the DNA/chitosan membrane exhibited excellent electrochemical redox property with an electron transfer rate constant of 3.12 ± 0.5 sec−1, and shuttled electron effectively from the base GC electrode to catalytic center of the HRP. Under the applied potential of -0.22V (versus Ag/AgCl) and pH 7.0, the resulting electrode (HRP/DNA–TB/chitosan/GCE) exhibited rapid (<10 s) and sensitive response to H2O2. The calibration curve of H2O2, plotting steady-state cathodic current versus H2O2 concentration, was linear up to 0.1mM with a detection limit of 1 μM H2O2 (S/N = 3). The H2O2 response was scarcely interfered by ascorbic acid and uric acid, which potentially reduce oxidized intermediate of the HRP and interfere with the response of peroxidase-based electrodes.
The electrochemical behavior of a new magnesium alloy (AZ61) containing rare earth elements-cerium (Mg-Al-Zn-Mn-Ce alloys) was investigated in 3% NaCl electrolyte using electrochemical methods such as linear sweep voltammetry, Tafel curves and electrochemical impedance spectroscopy. Scanning electron microscopy was used to characterize the surface morphologies of magnesium and its alloys. The results shows that compared with that of the most commonly used Mg alloy–AZ61, the cerium containing magnesium alloy exhibited higher electrochemical activity, and higher corrosion resistance. The electrochemical activity of Mg-Al-Zn-Mn-Ce was higher than that of Mg and Mg-Al-Zn-Mn-Ce alloys in 3% NaCl. The corrosion resistive order decreased in the following sequence: Mg-Al-Zn-Mn-Ce > Mg-Al-Zn-Mn > Mg. The electrolytes favored anodic magnesium oxidation, but the alloying element of Ce facilitated the formation of dense passive films on alloy surfaces.
More than a hundred models of clusters Ni4-xFexP (x=0~4) have been designed and computed in duplicate and fourfold state on density function theory (DFT) to simulate amorphous alloys Ni80-xFexP20 that were the most familiar proportions in Ni-Fe-P amorphous system. The geometry, energy, electronic and catalytic properties have been discussed. The results disclosed that clusters could reflect some characteristic properties of binary amorphous alloys. And the clusters could predict the geometry and electron properties of corresponding ternary amorphous alloys. The addition of third element could enhance the system stability of Ni-P amorphous alloys. The metal atoms are the electrons gainers and metalloid atoms are the electrons offers in the clusters, and the ability of gaining electrons of atoms Ni is better than the one of atoms Fe. The trend of cluster Ni2Fe2P forming may be the keenest in clusters. It also would offer more excellent catalytic activity basing on Fermi level and density of state.
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