Topic
Ferrocene
About: Ferrocene is a research topic. Over the lifetime, 6175 publications have been published within this topic receiving 128796 citations. The topic is also known as: Dicyclopentadienyl iron & bis(Cyclopentadienyl)iron.
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TL;DR: Type III adenosine deaminase would be the best choice for the construction of an immobilized enzyme electrode both from the point of view of apparent Km and Vmax values and from the less pronounced product inhibition effect on the type III enzyme compared to the Type V enzyme.
Abstract: for each type of enzyme but in an opposite direction for each. The type III enzyme experiences an increase in apparent Km with increasing inosine concentration, while the type V enzyme shows a slight decrease in apparent Km at high inosine concentration. The most dramatic homogeneous effect is that of increasing inosine concentration upon the VmM values, however. For the type III enzyme, apparent VmiU! is reduced by nearly a factor of 2 but, for the type V enzyme, apparent Vma, decreases more than 7-fold. Such product inhibition reveals itself through longer response times in the immobilized enzyme electrodes. The results obtained in this study show that the potentiometric ammonia gas-sensing enzyme electrode does exhibit linear responses to substrate concentrations both above and below the Km value of the adenosine deaminase enzyme when sufficient enzyme is immobilized at the electrode surface. The BSA-glutaraldehyde cross-link provides for stabilization of the enzyme activity as shown by the observed electrode lifetime. Comparison of the homogeneous kinetic parameters with those obtained from the immobilized study reveals significant changes in the kinetic properties of the enzyme when it is immobilized, possibly resulting from conformational changes in the enzyme upon exposure to BSA and glutaraldehyde. The magnitude of the effect of addition of inosine on apparent Km and Vmax depends upon whether the enzyme is immobilized or free in solution. The apparent Km for the immobilized enzyme remained essentially constant upon addition of inosine, while the apparent Km for the homogeneous enzyme did show some variation but in opposite direction for the type III and V enzymes. In the construction of enzyme electrodes, it is desirable to obtain the highest (fastest rate) and lowest Km (greatest affinity) values possible. From the results of this study carried out at high enzyme levels it is apparent that type III adenosine deaminase would be the best choice for the construction of an immobilized enzyme electrode both from the point of view of apparent Km and Vmax values and from the less pronounced product inhibition effect on the type III enzyme compared to the Type V enzyme. Even in the absence of initial inosine, type III enzyme electrodes have faster response times than corresponding electrodes prepared with type V enzyme.
1,687 citations
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TL;DR: In this article, the authors indique les procedes pour la mesure et le report des potentiels d'electrode dans des solvants non aqueux, vis-a-vis de ces systemes redox de reference.
Abstract: On montre que les couples redox ferrocene/ion ferricenium, [ferrocene: bis(η-cyclopentadienyl) fer(II)] et bis(biphenyl) chrome(I)/bis(biphenyl)-chrome(o) peuvent etre utilises comme systemes redox de reference. On indique les procedes pour la mesure et le report des potentiels d'electrode dans des solvants non aqueux, vis-a-vis de ces systemes redox de reference. Donnees numeriques obtenues dans 22 solvants organiques
1,168 citations
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1,130 citations
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TL;DR: In this paper, a self-assembled monolayer with low concentrations of alkanethiols linked to ferrocene by a polar ester group (FcCO{sub 2}(CH{sub n}SH, Fc = ({eta}{sup 5}-C{sub 5}H{sub 4}Fe }) showed thermodynamically ideal surface electrochemistry.
Abstract: Self-assembled monolayers provide an ideal system for disentangling the fundamental events in interfacial electron transfer. Coadsorption of ferrocene-terminated alkanethiols with unsubstituted n-alkanethiols on evaporated gold films yields stable, electroactive self-assembled monolayers. Monolayers containing low concentrations of alkanethiols linked to ferrocene by a polar ester group (FcCO{sub 2}(CH{sub 2}){sub n}SH, Fc = ({eta}{sup 5}-C{sub 5}H{sub 5})Fe({eta}{sup 5}-C{sub 5}H{sub 4})) show thermodynamically ideal surface electrochemistry in 1 M HClO{sub 4}, indicating the ferrocene groups to be homogeneous and noninteracting. Higher surface concentrations or use of alkanethiols linked directly to the nonpolar ferrocene group (Fc(CH{sub 2}){sub n}SH) lead to broadened electrochemical features, indicating interactions among ferrocene groups or inhomogeneous sites. Longer chain lengths and lower ferrocene surface concentrations result in slower electron-transfer kinetics with the ferrocene groups. A fraction of the thiols in a monolayer exchange with thiols in an ethanol solution, but much of the monolayer remains unequilibrated after 10 days.
933 citations
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631 citations