Bioelectronic devices

On the other hand, if the hole flow in DNA could be artificially controlled to deposit at the desired site in DNA, it may enable site-selective oxidation and strand scission of DNA, which is desirable from a therapeutical standpoint. Furthermore, understanding DNA-mediated hole transfer is expected to lead to an additional application in the development of biosensors and bioelectronic devices [9]. Therefore, the regulation of the transfer rate and direction of the hole generated in DNA is of interest from the perspective of using DNA as a building block for electronic devices. 

Interest in these studies arises from fundamental research where monolayers serve as models of biomimetic systems, as well as from important apphcations of such systems in molecular and bioelectronic devices, in sensors constructions, corrosion/inhibition phenomena, and synthesis of nanostructures... 

Metallic nanoparticles and single-walled carbon nanotubes (SWCNTs) exhibit nanoscale dimensions comparable with the dimensions of redox proteins. This enables the construction of NP-enzyme or SWCNT-enzyme hybrids that combine the unique conductivity features of the nanoelements with the biocatalytic redox properties of the enzymes, to yield wired bioelectrocatalyts with large electrode surface areas. Indeed, substantial advances in nanobiotechnology were achieved by the integration of redox enzymes with nanoelements and the use of the hybrid systems in different bioelectronic devices.35... 

Methods to electrically wire redox proteins with electrodes by the reconstitution of apo-proteins on relay-cofactor units were discussed. Similarly, the application of conductive nanoelements, such as metallic nanoparticles or carbon nanotubes, provided an effective means to communicate the redox centers of proteins with electrodes, and to electrically activate their biocatalytic functions. These fundamental paradigms for the electrical contact of redox enzymes with electrodes were used to develop amperometric sensors and biofuel cells as bioelectronic devices. 

Wise KJ, Gillespie NB, Stuart JA, Krebs MP, Birge RR (2002) Optimization of bacteriorhodopsin for bioelectronic devices. Trends in Biotechnology 20(9) 387-394... 

Command surfaces based on isomerizable monolayers have also been used to detect various signals (temperature change [204], pH change [205]) by the variation of redox cofactor regeneration rates (therefore by the control of enzymatic activity). Thus, they represent examples of biocatalytic switches. All the systems described above represent examples of bioelectronic devices that can be used for the trans-... 

Combination of impedance spectroscopy with other physical methods (SPR, QCM, FUR spectroscopy) is especially productive in characterization of the interfacial properties of sensing and bioelectronic devices. 

The photoregulated electrical interactions between the various redox proteins and the electrode interfaces provide a means for the amperometric transduction and amplification of recorded optical signals. These integrated assemblies reveal the fundamental potential for future bioelectronic devices. 

The need to improve the electrical communication between redox proteins and electrodes, and the understanding that the structural orientation at the molecular level of redox proteins and electroactive relay units on the conductive surfaces is a key element to facilitate ET, introduced tremendous research efforts to nano-engineer enzyme electrodes with improved ET functionalities. The present chapter addresses recent advances in the assembly of structurally aligned enzyme layers on electrodes by means of surface reconstitution and surface crosslinking of structurally oriented enzyme/cofactor complexes on electrodes. The ET properties of the nano-structured interfaces is discussed, as well as the possible application of the systems in bioelectronic devices such as biosensors, biofuel cell elements or optical and electrical switches. 

Although complex, the cytochromes c3 provide the opportunity to obtain information that will greatly extend our knowledge of biological electron transfer and the interaction of redox centers in multiheme proteins. Moreover, because of unique electrochemistry and electrical properties, the cytochromes c3 provide the opportunity to develop a system useful as a model for bioelectronic devices. Much research remains to be done to understand fully the redox properties of the cytochromes c3. However, the data discussed clearly define interesting and important issues, which include (1) the paths by which electrons move between hemes (2) how electrons enter and exit the cytochrome c3 molecule during physiological electron transfer (3) the nature of the factors that control the interaction potentials between hemes (4) the factors responsible for the observed behavior on metal surfaces and, importantly, (5) the specific molecular features responsible for the behavior of... 

Y. Xiurong, W. Xiaolei, Z. Hui and X. Xiaowen, in Functional Nanoparticles for Bioanalysis, Nanomedicine, and Bioelectronic Devices Volume 1, American Chemical Society, 2012, ch. 9, vol. 1112, ACS Symposium Series, pp. 241-279. 

In vivo applications of bioelectronic devices, such as artificial limbs, cochlear or retina implants, will not be stressed here in detail. Many of the problems thathave to be solved for in vitro devices, such as a stable neuron/electrode contact, do also matter for in vivo applications. However, for the latter, much more difficult requirements have to be met, such as biocompatibility not only against the neural cells but the whole body, including resistance to body reactions against the foreign device such as inflammation or scar formation, mechanical stabiHty in a moving system (muscle, eye,...), long-term stabitity over years, as well as practical requirements such as easy implantation. Despite all these difficulties, there are systems such as pacemakers and cochlear implants already on the market [37]. Retina implants are under development [38]. And first studies are made with intelligent artificial limbs. Therefore one can hope that in the twenty-first century many of the above-mentioned problems will be solved. 

A number of successful bioelectronic devices have been created that exploit miaoelec-trode technology. These include the cochlear implant and peripherally implantable stimulators (27). Other devices including retinal or cortical implants are less developed and not yet applicable. A challenge in this field is to engineer microelectrode surfaces so that they are both biocompatible and can be used to direct cell adhesion and growth (e.g., to stimulate nerve growth across an interrupted neuronal pathway). 

Dendrimers and star polymers containing redox active sites have been utilized in the design of new types of catalysts, sensors, bioelectronic devices, and molecular batteries. Highly branched polymers containing arenes coordinated to oiganometallic moieties have been prepared witii chromium tricarbonyl, cyclopenta-dienyliron, " and pentamethylcyclopentadienylrutheniiun moieties. Astruc and... 

Biocatalytic electrodes and biofuel cells controlled by biomolecular signals and implantable biofuel cells operating in vivo - towards bioelectronic devices integrating biological and electronic systems... 

Implantable Bioelectronics - Devices, Materials and Applications, ed. E. Katz, Wiley-VCH, Weinheim, 2014. 

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