Monolayer-functionalized

As dehydrogenases (DH) are widely distributed enzymes, a number of studies have been carried out with these biocatalysts. For example, Willner el al. [20] have used a PQQ-monolayer functionalized gold electrode for the catalytic oxidation of NADH in the presence of Ca2+. In this scheme, the pyrrolo-quinoline quinine co-factor, PQQ, was covalently linked, as before for the GOx system [15, 20, 21], to the Au electrode,... 

The reconstitution of apo-enzymes on relay-cofactor monolayer-functionalized electrodes was used to align redox enzymes and to establish electrical contact... 

Figure 5.42 Cyclic amperometric responses of a ft-CD functionalized monolayer on photoswitching of the bipyridinium-azobenzene diad currents are measured at a constant potential of —0.6 V. From M. Lahav, K. T. Ranjit, E. Katz and I. Willner, Photosimulated interactions of bipyridinium-azobenzene with a /3-aminocyclodextrin monolayer-functionalized electrode An optoelectronic assembly for the amperometric transduction of recorded optical signals, Isr.. Chem., 37, 185-195 (1997). Reproduced by permission of Laser Pages...

The association of the DNP-Ab to the antigen-monolayer-functionalized electrode leads to the electrical insulation of the electrode support and to the introduction of an electron barrier at the electrode surface. Thus, in the presence of an electrically wired enzyme (e.g., ferrocene-tethered glucose oxidase), the bioelectrocatalytic current is inhibited upon the formation of... 

Marx-Tibbon, S., Ben-Dov, I., and Willner, I. Electrochemical and quartz-crystal-microbalance transduction of light-controlled supramolecular interactions for monolayer-functionalized electrodes./. Am. Chem. Soc. 1996,118, 4717-4718. 

For a further discussion of monolayer functions of state from a thermodynamic, or pseudo-thermodynamic, point of view, see for example E.H. Lucassen-Reijnders, Progr. Surface Membr. Set 10, D.A. Cadenhead, J.F. Danlelli Eds. Academic Press (1976) 253 G.L. Gaines Jr., J. Chem. Phys. 69 (1978) 924 S-S. Feng, H.L. Brockman and R.C. MacDonald, Langmuir 10 (1994) 3188. 

Recently, the fabrication of a sensor array in a chip by covalent attachment of fluorescent monolayers on the walls of glass microchannels has been demonstrated. The monolayer array (confined in a multichannel chip) is prepared by parallel synthesis of monolayers functionalized with different fluorophore-ligand pairs, resulting in a sensing chip, which is able to generate a fingerprint of the network with a single fluorescence snapshot for different analytes.63... 

The AFM FV measurements are carried out in contact mode using 11-mercapto-1-undecanol monolayer functionalized gold-coated probe tips (these functionalized probes are commercially available, see Appendix, or can be prepared according to the literature [10]). All measurements are performed in Milli-Q water using a liquid cell without O-ring (see Sect. 3.3 in Chap. 3). The use of very soft cantilevers with a nominal spring constant of 0.06 N/m is advisable. 

Reconstitution of apo-glucose dehydrogenase on a PQQ-monolayer-functionalized Au-electrode led to an active configuration of the enzyme on the electrode support, but it lacked direct electrical contact with the electrode... 

The formation of a complex between the eosin-functionalized Au/quartz crystal and 53a results in a mass increase on the transducer, leading to a decrease in the crystal frequency. Photoisomerization of the electron acceptor to the 53b-state, Fig. 28B, yields an acceptor of lower affinity for the eosin interface. Thus, dissociation of the n donor-acceptor complex occurs, causing a decrease in the mass on the crystal (i.e. an increase of the crystal s resonant frequency). Figure 28C shows the frequency changes of the eosin monolayer-functionalized Au/quartz crystal upon its interaction with 53a and 53b. While the association of 53a is accompanied by a frequency decrease of Af — —25 Hz, the binding of 53b to the modified surface results in a frequency change of... 

The sorption model was derived from studies to determine the quantity of solvent adsorbed to the surface of silica. Experimental evidence suggests that silica adsorbs water to its surface, some of which can be removed by either heating to 110 °C, or by sequential organic phase extraction. More can be removed at very high temperatures, but this also results in the breakdown of silanol groups (Scott, 1982). Measurement of the adsorption of different concentrations of polar modifiers in an inert solvent allows the adsorption isotherms to be calculated (Fig. 6.2). When the concentration of the modifier is low, the isotherm fits closest to a monolayer function. When the polar modifier is present at a high concentration a bilayer adsorption isotherm function is produced ... 

Fig. 6.2. A plot of the Langmuir adsorption isotherm for three non-polar solvents (chloroform, butyl chloride and benzene) in n-heptane. It can be seen that the data fit very closely to the monolayer function y = x/(A + Bx). Reproduced from Scott and...

Figure 6.3 Modification of monolayer-functionalized QDs with molecular or macromolecular components, (a, b) Covalent attachment (c) Attachment of ligand (d) Electrostatic association of a...

Figure 11.2 [a) Preparation of a bis-aniline-cross-linked GOD monolayer on Au electrode by the electropotymerization of the thioaniline-modified GOD with the thioaniline monolayer -functionalized Au electrode, [b) Preparation of the 3D bis-aniline-cross-linked CNT-GOD composite by the electropo-tymerization of the thioaniline-modified GOD and aniline-modified CNTk on thioaniline monolayer-functionalized Au electrode [reproduced with permission from the ref. 34, 2009, American Chemical Society). 

Wang, X. M. Kharitonov, A. B. Katz, E. WiUner, I. Potential-controlled molecular machinery of bipyridininm monolayer-functionalized surfaces an electrochemical and contact angle analysis. Chem. Commun. 2003, 75,1542-1543. 

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