Biorecognition

The optimization of the biorecognition layer by the modification of a transducer used. Nanostmctured poly aniline composite comprising Prussian Blue or poly-ionic polymers has been synthesized and successfully used in the assembly of cholinesterase sensors. In comparison with non-modified sensors, this improved signal selectivity toward electrochemically active species and decreased the detection limits of Chloropyrifos-Methyl and Methyl-Pai athion down to 10 and 3 ppb, respectively. 

Novel glycerol and formaldehyde selective sensors based on pEI-Sensitive Field Effect Transistors as transducers and Glycerol Dehydrogenase and Formaldehyde Dehydrogenase as biorecognition elements have been developed. The main analytical parameters of the sensors have been investigated and will be discussed. 

L-lactate-cytochrome c-oxidoreductase (flavocytochrome was isolated for the first time from the thermo-tolerant yeast H. polymorpha. The mentioned above enzyme preparations were used for construction of the biorecognition elements of electrochemical sensors. 

The branched polysaccharide dextran is assembled with alkanethiol-modified gold nanoparticles and the resulting nanocomposite is then functionalized to facilitate the specific binding of target biomolecules. This biorecognition process can be easily detected by particle plasmon resonance (PPR), based on the optical properties of gold nanoparticles [163]. 

The continuous monitoring of the analyte concentration is one of the most attractive applications of sensors which cannot be substituted with any other immunoanalytical methods. Biorecognition layers allowing the... 

Weisser, M. Tovar, G. Mittler Neher, S. Knoll, W. Brosinger, F. Freimuth, H. Lacher, M. Ehrfeld, W., Specific biorecognition reactions observed with and integrated Mach Zehnder interferometer, Biosens. Bioelectron. 1999, 14,405 411... 

Fig. 14.5 Surface chemistry The OFRR glass surface is biofunctionalized with 3APS. Then biorecognition molecules are immobilized using a cross linker...

In these previous experiments, BSA is captured at the interior surface of the OFRR capillary, but these instructional experiments do not use a specific biorecognition... 

All DNA hybridization assays are subject to cross-hybridization, in which an oligonucleotide that is not a perfect sequence match hybridizes with the capture probe. The cross-hybridization in the OFRR was investigated using samples of oligonucleotides with either 0-, 1-, 2-, 5-, or 25-base mismatches when compared with the 25 base-pair biorecognition capture probe. The resulting resonant mode spectral shifts for the respective mismatch are plotted in Fig. 14.7b. The measurements show a difference of 1.3 pm and 2.8 pm for one and two base-pair... 

In recent years many efforts have been made to develop immunochemical techniques integrating the recognition elements and the detection components, in order to obtain small devices with the ability to carry out direct, selective, and continuous measurements of one or several analytes present in the sample. In this context biosensors can fulfill these requirements. Biosensors are analytical devices consisting of a biological component (enzyme, receptor, DNA, cell, Ab, etc.) in intimate contact with a physical transducer that converts the biorecognition process into a measurable signal (electrical or optical) (see Fig. 4). In... 

Fig. 4 Schematic representation of a generic biosensor with the essential components (biorecognition element, transducer, and electronic part involved in data processing and display)...

David, A., Kopeckova, P., Rubinstein, A., Kopecek, J., Enhanced biorecognition and internalization of HPMA copolymers containing multiple or multivalent carbohydrate side-chains by human hepatocarcinoma cells. Bioconjug Chem 12, 890-... 

Figure 2 Examples of coiled-coils used as engineering materials—transplantable oligomerization module (a) [24,25,27], epitope-displaying scaffold (b) [26], biorecognition element (c) [28], allosteric switch (d) [29], and self-replicating peptide (e) [30]. 

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