Electrochemical sensors, molecular wire

Apart from electron promoters a large number of electron mediators have long been investigated to make redox enzymes electrochemically active on the electrode surface. In the line of this research electron mediators such as ferrocene and its derivatives have successfully been incorporated into an enzyme sensor for glucose [3]. The mediator was easily accessible to both glucose oxidase and an electron tunnelling pathway could be formed within the enzyme molecule [4]. The present authors [5,6] and Lowe and Foulds [7] used a conducting polymer as a molecular wire to connect a redox enzyme molecule to the electrode surface. 

Liu et al. [140] have also used this interface for an electrochemical immunosensor for small molecules (Figure 1.26). In this sensor, one end of the molecular wire is attached to ferrocene dimethylamine with a covalent link formed between one of the amine group son the ferrocene and the carboxyl group on the wire. To the other amine is attached the antibody-binding epitope for the antibody, in this proof-of-concept study the epitope is biotin. Electron transfer can be readily achieved to the ferrocene molecule but upon antibody binding to this interface, the electrochemical signal is dramatically reduced. 

The covalent chemistry of fullerenes has developed very rapidly in the past decade in an effort to modify fuUerene properties for a number of applications such as photovoltaic cells, infrared detectors, optical limiting devices, chemical gas sensors, three-dimensional electroactive polymers, and molecular wires [8, 25, 26, 80-82]. Systematic studies of the redox properties of Cgo derivatives have played a crucial role in the characterization of their unique electronic properties, which lie at the center of these potential applications. Furthermore, electrochemical techniques have been used to synthesize and separate new fullerene derivatives and their isomers as well as to prepare fullerene containing thin films and polymers. In this section, to facilitate discussion of their redox properties, Cgo derivatives have been classified in three groups on the basis of the type of attachment of the addend to the fullerene. In group one, the addends are attached via single bonds to the Cgo surface as shown in Fig. 6(a) and are referred to as singly bonded functionalized derivatives. The group includes... 

In conclusion, this book is intended as an overview of the principles behind and state-of-the-art in interfacial supramolecular chemistry. The book is suitable for researchers and graduate students and focuses on assemblies that demonstrate at least the potential to produce useful devices such as solar cells, electrochromic devices, molecular wires, switches and sensors which are addressable by using electrochemical and optical stimuli. Molecular materials for nanoscale molecular devices remain an intriguing conceptual possibility. 

Fig. 9.13 Electrochemical detection of nucleic acid with the bioelectronic sensor based on a sandwich assay. A target nucleic acid is shown to anneal to a capture probe and a ferrocene-labeled signaling probe [58]. The thiol-terminated oligophenylethynyl molecules serve as molecular wires and provide a...

Gun J., Lev O. Sol-gel derived, ferrocenyl-modified silicate-graphite composite electrode Wiring of glucose oxidase. Anal. Chim. Acta 1996b 336(1-3) 95-106 Guo Y.Z., Guadalupe A.R. Screen-printable surfactant-induced sol-gel graphite coirposites for electrochemical sensors. Sensors Actuators B Chem. 1998 46(3) 213-219 Haupt K., Mosbach K. Molecularly imprinted pol3uners and their use in biomimetic sensors. Chem. Rev. 2000 100(7) 2495-2504... 

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