Bioreceptors

Utilize a biochemical mechanism for recognition. They are responsible for binding the analyte of interest to the sensor surface for the measurement. Bioreceptors can generally be classified into five major categories enzyme, antibody/antigen, nucleic acid/DNA, cellular structure/ceU, and biomimetic. The sampling component of a biosensor contains a biosensitive layer that can contain bioreceptors or be made of bioreceptors cova-lendy attached to the transducer. The most common forms of bioreceptors used in biosensing are based on  

Interactions using biomimetic materials (i.e., synthetic bio receptors) 

The enzymes and antibodies are the main classes of bioreceptors that are widely used in biosensor applications. 

A bioreceptor must be able to react specifically with an analyte of interest. For example, a bioreceptor for cholesterol should react only with cholesterol and not with any other compound in the sample. Biological recognition systems such as enzymes or antibodies offer this high specificity and, in addition, ensure high sensitivity and fast response. Usually, the bioreceptor molecules are immobilised at, or close to, the surface of the transducer. Immobilisation can be achieved by physical adsorption or entrapment by an inert membrane. The bioreceptor can also be covalently bound to functional groups on the surface of the transducer. 

Enzymes are the biomolecules most commonly used as receptors in biosensors. As described in section 5.1.6, enzymes are protein molecules that catalyse chemical reactions. An enzyme can catalyse the conversion of a substrate A to a product B and itself remain unchanged after the reaction. Hence only small quantities of enzyme molecules are required on the surface of a biosensor, as they can regenerate themselves after reacting. Any given enzyme will always turn A into B and never into C and, equally, the same enzyme is extremely unlikely to take D and synthesise 

Enzymes are highly specific in their action and this specificity of enzymatic 

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C and T E Klein 1986. Molecular Graphics and QSAR in the Study of Enzyme-Ligand ractions. On the Definition of Bioreceptors. A ccounts of Chemical Research 19 392-400,... 

SENSORS BASED ON FREE-STANDING MOLECULARLY IMPRINTED POLYMER MEMBRANES. COMPUTATIONAL MODELLING OF SYNTHETIC MIMICKS OF BIORECEPTORS... 

Biosensors play a significant role in the monitoring of a wide range of diseases and pathogens. A biosensor is an analytical device, which incorporates a biological recognition element or bioreceptor which is capable of sensing the presence. 

The potential use of SERS in biodiagnostic tests has been demonstrated through the use of immobilized monolayers of bioreceptors, including oligonucleotides and antibodies. The use of surface-enhanced Raman gene... 

Brynda E., Houska M., Skvor J., Ramsden J.J., Immobilisation of multilayer bioreceptor assemblies on solid substrates. Biosens, Bioelectron. 1998 13 165-172. 

Hansch, C. and Klein, T.E. (1986) Molecular graphics and QSAR in the study of enzyme-ligand interactions. On the definition of bioreceptors. Accounts of Chemical Research, 19, 392-400. 

Bioreceptors Antibodies Lectins Cell membrane receptors Nucleic acids Synthetic molecules... 

J. S. Schultz, Design of fibre-optic biosensors based on bioreceptors, in Biosensors Fundamentals andApplications (A. P. F. Turner, I. Karobe, and G. S. Wilson, eds.), Oxford University Press, New York (1987). 

The analytical device is represented by an amperometric biosensor able to monitor the evolution of photosynthetic 02, obtained by coupling a suited algal bioreceptor to a Clark electrode. The selected algal species is the marine filamentous cyanobacterium Spirulina subsalsa (Campanella [4]). Further details on the application of biosensors for integral toxicity... 

In a typical configuration of a DNA biosensor, the bioreceptor is an ssDNA called the capture probe that is immobilised by one of the methods described above. The analyte, a complementary ssDNA called... 

Adrian, J., D.G. Pinacho, B. Granier, et al. 2008. A multianalyte ELISA for immunochemical screening of sulfonamide, fluoroquinolone and 13-lactam antibiotics in milk samples using class-selective bioreceptors. Anal. Bioanal. Chem. 391 1703-1712. 

Jiang P, Guo Z. Fluorescent detection of zinc in biological systems recent development on the design of chemosensors and bioreceptors. Coord Chem Rev 2004 248 205-29. 

A different approach has been the coupling of microdialysis with biosensing techniques. These latter are non-separation techniques based on molecular recognition of the target analjde, which may form a complex with a bioreceptor, allowing its selective identification even in a complex mixture. 

The reaction between the analjrte and the bioreceptor produces a physical or chemical output signal normally relayed to a transducer, which then generally converts it into an electrical signal, providing quantitative information of analytical interest. The transducers can be classified based on the technique utilized for measurement, being optical (absorption, luminescence, surface plasmon resonance), electrochemical, calorimetric, or mass sensitive measurements (microbalance, surface acoustic wave), etc. If the molecular recognition system and the physicochemical transducer are in direct spatial contact, the system can be defined as a biosensor [76]. A number of books have been published on this subject and they provide details concerning definitions, properties, and construction of these devices [77-82]. 

Easy electrochemical control of the surface single step suitable for the fabrication of micro sensors control and orientation of biomolecules Simple many biocompatible pol5miers available suitable for a large variety of bioreceptors Reusable surface... 

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