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Single-metalloprotein wet biotransistor
No full textMetalloproteins are redox molecules naturally shuttling electrons with high efficiency between molecular partners. As such, they are candidates of choice for bioelectronics. In this work, we have used bacterial metalloprotein azurin, hosted in a nanometer gap between two electrically biased gold electrodes, to demonstrate an electrochemically gated single-molecule transistor operating in an aqueous environment. Gold-chemisorbed azurin shows peaks in tunneling current upon changing electrode potential and a related variation in tunneling barrier transparency which can be exploited to switch an electron current through it. These results suggest the wet approach to molecular electronics as a viable method for exploiting electron transfer of highly specialized biomolecules. ©2005 American Institute of Physic
Protein-based transistors
No full textIntroduction: A survey of proteins in nanobioelectronics The idea of using proteins to assemble hybrid electronic devices stems from molecular electronics [1] and, as such, it is intimately connected with the advent of nanosciences and nanotechnologies, dating back to the early 1990s. Since then, much technological effort but less scientific effort has been deployed to try to implement devices that take advantage of the peculiar features of proteins. A technologist’s standpoint is that of regarding proteins as self-contained, nanometer-sized functional units, highly specialized and efficient in performing a certain functional task. Their efficiency is traced back to the fact that, being active parts of living beings, proteins are taking advantage of billions of years of natural evolution in specializing towards a given activity. This way of thinking, which one can often encounter in ritten or spoken accounts, appears to be questionable in light of a rather less naïve understanding of the theory of evolution, but is perhaps a good enough starting point to understand the historical motivations which led to the remarkable interest of a interdisciplinary part of the scientific community in the use of proteins for assembling electronic devices. The other aspect motivating the interest in proteins as elements in electronic circuits is their size
Electrochemically assisted scanning probe microscopy: A powerful tool in nano(bio)science
No full textNanosciences, in general and nanobiophysics, in particular,have taken much advantage of the advent of scanning probemicroscopies. These instruments have enabled real space visualizationof atoms and molecules allowing the retrieval of unprecedentedlyaccurate information. Nevertheless, the most powerful implementationsof scanning probe microscopies should also enable a full controlof the phenomena taking place at solid–liquid interfaces (e.g., electrochemicalreactions). In this chapter, we will review the applicationsof scanning probe microscopies (STM and SFM) under electrochemicalcontrol. In particular, we will firstly present the fundamentals ofelectrochemically controlled scanning tunnelling microscopy, as faras basic concepts and possible set-ups are concerned, and proceedto the basic applications involving characterization of clean surfaces,study of underpotential deposition of metals, potential-induced phasetransitions in molecular layers. The further paragraphs will be devotedto reviewing biophysical applications of electrochemical scanning tunnellingmicroscopy (EC-STM) as far as investigation on redox metalloproteinsis concerned. A discussion on the state-of-the-art videorate EC-STM is provided. In the last sections, we will present the currentand future efforts aimed at further developing electrochemicallyassisted scanning probe microscopy towards the implementation of anelectrochemically controlled current sensing atomic force microscopewith the fundamental contribution of state-of-the-art nanotechnology.Nanosciences in general and nanobiophysics, in particular, have taken much advantage of the advent of scanning probe microscopies. These instruments have enabled real space visualization of atoms and molecules allowing the retrieval of unprecedentedly accurate information. Nevertheless, the most powerful implementations of scanning probe microscopies should also enable a full control of the phenomena taking place at solid-liquid interfaces (e.g., electrochemical reactions). This chapter reviews the applications of scanning probe microscopies (STM and SFM) under electrochemical control. In particular, it presents the fundamentals of electrochemically controlled scanning tunneling microscopy, as far as basic concepts and possible set-ups are concerned, and proceed to the basic applications involving characterization of clean surfaces, study of underpotential deposition of metals, potential-induced phase transitions in molecular layers. The further paragraphs will be devoted to reviewing biophysical applications of electrochemical scanning tunneling microscopy (EC-STM) as far as investigation on redox metalloproteins is concerned. A discussion on the state-of-the-art video rate EC-STM is provided. Finally, this chapter presents the current and future efforts aimed at further developing electrochemically assisted scanning probe microscopy towards the implementation of an electrochemically controlled current sensing atomic force microscope with the fundamental contribution of state-of-the-art nanotechnology. © 2008 Elsevier Ltd All rights reserved
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