Biological component

Materials that produce harmful effects must come into close stmctural or functional relationship with the tissue or organ they may affect. As a result, they can physically or chemically interact with particular biological components in order to effect the toxic response. 

Biosensors ai e widely used to the detection of hazardous contaminants in foodstuffs, soil and fresh waters. Due to high sensitivity, simple design, low cost and real-time measurement mode biosensors ai e considered as an alternative to conventional analytical techniques, e.g. GC or HPLC. Although the sensitivity and selectivity of contaminant detection is mainly determined by a biological component, i.e. enzyme or antibodies, the biosensor performance can be efficiently controlled by the optimization of its assembly and working conditions. In this report, the prospects to the improvement of pesticide detection with cholinesterase sensors based on modified screen-printed electrodes are summarized. The following opportunities for the controlled improvement of analytical characteristics of anticholinesterase pesticides ai e discussed ... 

The sensitivity of the ocean s chemical role in climate is yet to be fully explored as development of models for the carbon and biological components of oceanic... 

In 1998, the FDA approved fibrin sealant for three specific indications. These include hemostasis at the time of cardiac surgical operations [8] (Fig. 2) as well as at the time of operative procedures to treat splenic trauma. The application of the fibrin sealant which consists of normal biologic components in the body s clotting cascade creates a localized clot which further enhances inherent clotting ability. Although approved for these specific hemostatic indications only, fibrin sealant is useful as a hemostat in a wide variety of off-label clinical situations as well [9,10]. These include such applications as hemostasis for liver trauma or resection [11], vascular anastomoses [12], tonsillectomy [13], peripheral joint replacement [14], dental extractions [15], and bum debridement [16]. 

Disturbances (both natural and anthropogenic) that increase nutrient concentration may cause the river biological components and metabolism to shift from natural heterotrophy toautotrophy, even in relatively pristine rivers. Enforced hydrological stability or increased nutrient loading, among many other disturbances, may cause pronounced changes in system metabolism. 

Nanotechnology refers to electrical, optical, and mechanical devices, sometimes with biological components, with sizes that range from a few hundred nanometers down to the size of individual molecules. It is a burgeoning field of diverse methodologies. This section highlights a few uses of chemical reactions to fabricate such devices. 

A challenge in designing liposome systems is the assessment of drug release from such systems in vitro. Use of agarose gel matrices has been reported as one approach to evaluate the release kinetics of liposome-encapsulated materials in the presence of biological components [68],... 

By manipulating genes, chemists have learned to create new enzymes with new functions. To do this rationally and predictably, it is critical to understand the structures and mechanisms of the genes that are being modified. Enzymes and other biological components often function in clusters, in multicomponent sys-... 

The preceding accomplishments are applied in nature, but required tremendous amounts of basic research on mass transfer, interactions of materials with biological components, fluid dynamics, separation processes (especially chromatography and membrane separations), and biochemical kinetics. 

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... 

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