18,658 research outputs found
DNA sensing by electrocatalysis with hemoglobin
Electrocatalysis offers a means of electrochemical signal amplification, yet in DNA-based sensors, electrocatalysis has required high-density DNA films and strict assembly and passivation conditions. Here, we describe the use of hemoglobin as a robust and effective electron sink for electrocatalysis in DNA sensing on low-density DNA films. Protein shielding of the heme redox center minimizes direct reduction at the electrode surface and permits assays on low-density DNA films. Electrocatalysis with methylene blue that is covalently tethered to the DNA by a flexible alkyl chain linkage allows for efficient interactions with both the base stack and hemoglobin. Consistent suppression of the redox signal upon incorporation of a single cytosine-adenine (CA) mismatch in the DNA oligomer demonstrates that both the unamplified and the electrocatalytically amplified redox signals are generated through DNA-mediated charge transport. Electrocatalysis with hemoglobin is robust: It is stable to pH and temperature variations. The utility and applicability of electrocatalysis with hemoglobin is demonstrated through restriction enzyme detection, and an enhancement in sensitivity permits femtomole DNA sampling
Electrocatalytic phenomena in gas phase reactions in solid electrolyte electrochemical cells
The recent literature on electrocatalysis and electrocatalytic phenomena occurring in gas phase reactions on solid, oxygen conducting electrolytes is reviewed. In this field there are a number of different subjects which are treated separately. These are: the use of electrochemical methods to study catalytic phenomena, electrocatalysis proper, the transfer of oxygen at the electrodes or electrolyte, and the (electro)catalytic properties of mixed, electronic and ionic, conducting materials
Graphene-Based Nanostructures in Electrocatalytic Oxygen Reduction
Application of graphene-type materials in electrocatalysis is a topic of
growing scientific and technological interest. A tremendous amount of research
has been carried out in the field of oxygen electroreduction, particularly with
respect to potential applications in the fuel cell research also with use of
graphene-type catalytic components. This work addresses fundamental aspects and
potential applications of graphene structures in the oxygen reduction
electrocatalysis. Special attention will be paid to creation of catalytically
active sites by using non-metallic heteroatoms as dopants, formation of
hierarchical nanostructured electrocatalysts, their long-term stability, and
application as supports for dispersed metals (activating interactions)
Multi-vanadium substituted polyoxometalates as efficient electrocatalysts for the oxidation of l-cysteine at low potential on glassy carbon electrodes
The electrochemical behaviours of the sandwich-type complex
[As2W18(VO)3O66]11- were studied in a pH 7 medium and compared with those of
the three following Dawson-type vanadium-substituted complexes: [P2V2W16O62]8-
(P2V2W16), [P2MoV2W15O62]8- (P2MoV2W15) and [P2V3W15O62]9- (P2V3W15).
Electrochemistry shows that the sandwich-type POM contains 2 VIV centers and
one VV center and must be formulated As2V2IVVW18, in agreement with titration,
elemental analysis and magnetic measurements on this element.. All the POMs of
this work proved efficient for the oxidation of L-cysteine. Comparison of the
present results with those of mono-Vanadium substituted POMs indicates that
accumulation of vanadium atoms in the POM framework is beneficial in the
electrocatalytic process. In addition, the present work highlights the
important influence of the POM structure in the electrocatalytic oxidation of
L-cysteine. The remarkable outcome of this work is that the potential for the
oxidation of L-cysteine in the presence of the selected POMs has been
substantially driven in the negative direction compared to the case of glassy
carbon alone, a feature which is associated with faster kinetics. The stability
of the systems must also be pointed out
The Influence of Protonation on the Electroreduction of Bi (III) Ions in Chlorates (VII) Solutions of Different Water Activity
We examined the electroreduction of Bi (III) ions in
chlorate (VII) solutions under varied protonation conditions of
the depolariser using voltammetric and impedance methods.
The results of the kinetic parameter correlation lead to the
statement that the changes in the amount of chloric (VII) acid
against the amount of its sodium salt in the supporting electrolytes
of the low water activity have a significant influence
on the rate of Bi (III) ion electroreduction. The increase of the
concentration of chloric acid sodium salt, aswell as the chloric
(VII) acid alone within the particular concentration of the
supporting electrolyte, inhibits the process of Bi (III) ion
electroreduction. It should be associated with the
reorganisation of the structure of the double layer connected
with the slow dehydration inhibited by ClO 4
â ions. The standard
rate constants ks values with the increase of the chlorate
(VII) concentrations for all the solutions examined of chlorates
(VII) confirms the catalytic influence of the decrease of
water activity on the process of Bi (III) ion electroreduction.
The multistage process is confirmed by the non-rectilinear
1nkf=f(E) dependences
A combined "electrochemical-frustrated Lewis pair" approach to hydrogen activation: surface catalytic effects at platinum electrodes
Herein, we extend our âcombined electrochemicalâfrustrated Lewis pairâ approach to include Pt electrode surfaces for the first time. We found that the voltammetric response of an electrochemicalâfrustrated Lewis pair (FLP) system involving the B(C6F5)3/[HB(C6F5)3]â redox couple exhibits a strong surface electrocatalytic effect at Pt electrodes. Using a combination of kinetic competition studies in the presence of a H atom scavenger, 6-bromohexene, and by changing the steric bulk of the Lewis acid borane catalyst from B(C6F5)3 to B(C6Cl5)3, the mechanism of electrochemicalâFLP reactions on Pt surfaces was shown to be dominated by hydrogen-atom transfer (HAT) between Pt, [Pt[BOND]H] adatoms and transient [HB(C6F5)3]â
electrooxidation intermediates. These findings provide further insight into this new area of combining electrochemical and FLP reactions, and proffers additional avenues for exploration beyond energy generation, such as in electrosynthesis
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