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Liu Y.,Institute of Bio and Nanosystems IBN 2 | Offenhausser A.,Institute of Bio and Nanosystems IBN 2 | Mayer D.,Institute of Bio and Nanosystems IBN 2
Bioelectrochemistry | Year: 2010

In the present paper, we demonstrate the electrochemical rectification of a redox current which is transferred between redox probes (ferricyanide) in solution and a gold electrode functionalized with the biomolecular redox mediator microperoxidase-11 (MP-11). MP-11 is the redox active, heme-containing domain of the biological electron shuttle cytochrome c (cyt c). In our system, a unidirectional current develops due to selective electron transport from the bio-functionalized electrode to ferricyanide such that MP-11 controls the read-out of our coupled redox system. The electrode was functionalized by adding a monolayer of undecanethiol (UDT) to promote the physisorption of MP-11 and inhibit the direct electron transfer between redox probe and electrode. The relative position of redox donator, mediator, and acceptor equilibrium potentials defines the charge transport and a potential-dependent electrochemical current rectification. The results of our investigations demonstrate that functional building blocks of proteins can be reassembled into new conceptual devices with operation modes deviating from their native function, which could prove highly useful in future design of biosensors and bioelectronic systems. © 2009 Elsevier B.V. All rights reserved. Source

Jose Jr. R.S.,University of Sao Paulo | Jose Jr. R.S.,FH Aachen | Jose Jr. R.S.,Institute of Bio and Nanosystems IBN 2 | Maki R.M.,Julich Research Center | And 10 more authors.
Analytical Chemistry | Year: 2010

The integration of nanostructured films containing biomolecules and silicon-based technologies is a promising direction for reaching miniaturized biosensors that exhibit high sensitivity and selectivity. A challenge, however, is to avoid cross talk among sensing units in an array with multiple sensors located on a small area. In this letter, we describe an array of 16 sensing units of a light-addressable potentiometric sensor (LAPS), which was made with layer-by-layer (LbL) films of a poly(amidomine) dendrimer (PAMAM) and single-walled carbon nanotubes (SWNTs), coated with a layer of the enzyme penicillinase. A visual inspection of the data from constant-current measurements with liquid samples containing distinct concentrations of penicillin, glucose, or a buffer indicated a possible cross talk between units that contained penicillinase and those that did not With the use of multidimensional data projection techniques, normally employed in information visualization methods, we managed to distinguish the results from the modified LAPS, even in cases where the units were adjacent to each other. Furthermore, the plots generated with the interactive document map (IDMAP) projection technique enabled the distinction of the different concentrations of penicillin, from 5 mmol L-1 down to 0.5 mmol L-1. Data visualization also confirmed the enhanced performance of the sensing units containing carbon nanotubes, consistent with the analysis of results for LAPS sensors. The use of visual analytics, as with projection methods, may be essential to handle a large amount of data generated in multiple sensor arrays to achieve high performance in miniaturized systems. © 2010 American Chemical Society. Source

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