Redox amplification

Scanning electrochemical microscopy (SECM) sustains great interest for biomolecular recognition detection [29, 30]. This comes from the versatility of SECM methodology that offers versatile detection principles, e.g., positive or negative feedback modes together with collection mode that are compatible with unlabeUed hybridization detection as well as with redox amplification strategies of DNA hybridization [31, 32]. 

Neugebauer, S., Zimdars, A., Liepold, P., Gebala, M., Schuhmann, W., Hartwich, G. Optimization of an electrochemical DNA assay by using a 48-electrode array and redox amplification studies by means of scanning electrochemical microscopy. ChemBioChem 2009, 10,1193-1199. 

Several demonstrations of this concept have recently been published The first one is based on the pH dependence of redox transitions in oxide semiconductors that are connected with conductivity changes. If the bridging polymer layer in Fig. 6 is WO3 sputtered onto the electrode array or electrochemically deposited Ni(OH)j the transistor amplification is a function of the pH of the... 

Multielectron storage devices can be used as (i) redox catalysts, also called electron mediators, for multielectron processes, (ii) electrochemical sensors with signal amplification, and (iii) molecular batteries that can be foreseen to power molecular machines in the future or that can be used to construct flexible rechargeable batteries.10... 

Latent images or faint images in silver metal or other materials can be amplified by redox chemistries other than metal deposition. Several dye-forming redox chemistries have been discovered in which metal complexes serve as catalysts, catalyst precursors or one of the redox partners. The applications of coordination compounds in physical development and image amplification systems are therefore quite broad and diverse. 

Several other imaging systems based on Com/developer amplification are known, including systems with various diffusion transfer imaging chemistries. The principles are the same as those outlined here. Basically, most imaging chemistries useful with silver halide systems can be transformed into a low-silver or (sometimes) non-silver system with a suitable developer/Com complex redox combination for amplification on imagewise catalytic nuclei. 

Different strategies of electrochemical sensing have been used for DNA electrochemical detection (1) direct DNA electrochemistry, (2) indirect DNA electrochemistry, (3) DNA-specific redox indicator detection, (4) DNA-mediated charge transport, and (5) nanoparticle-based electrochemistry amplification. 

If the major aim of the ELISA is to obtain quantification of substances present in extremely low concentrations there are a number of adaptations to the technique that can be used. Such techniques often use alkaline phosphatase enzyme systems, which can be used, for example, to lock into a circular redox cycle producing an end product such as red formazan which, is hugely amplified in comparison to standard amplification methods (4). Chemiluminescent amplified ELISA principles have also been shown to give very high... 

Photoswitchable redox-enzymes 1. Amperometric transduction of optical information - biocomputers 2. Amplification of weak optical signals -photonic amplifiers 3. Multisensor arrays — biosensor and bioelectronics 4. Photoelectrochemical systems Enzyme immobilized on electronic transducer... 

Ascorbic acid (1) is most commonly used for testing the performance of electrodes in redox systems. Thus, a Ag-Ag ascorbate selective electrode was constructed with view to use it for vitamin C determination. Its reproducibility and stability was satisfactory and ascorbate ion concentration could be determined in neutral, alkaline and alcoholic media" . A voltametric study was carried out for the evaluation of graphite-epoxy composite (GEC) electrodes for use in the determination of ascorbic acid and hydroquinone. They were compared with mercury and CPE in similar operating conditions of pH and supporting electrolytes. Like all redox electrodes, also GEC electrodes deteriorate on exposure to air or after repeated usage, and the surface had to be renewed for activation. GEC electrodes were found to be adequate for redox system analyses"". The electrocatalytic oxidation of 1 is an amplification method for determination of specific miRNA strands using the An biosensor described in Table 1 . 

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