|MadSci Network: General Biology|
Scientists use a machine called a Biosensor which consisit of a round selectively permeable membrane ( acetyl cellulose ) and coated on a chip, which consist of two layers , the Biological recognition layer and transducer which feeds imformation to a computer. Reference Dictionary of Biology , Kane and Horne ------------------- Madministrator additional notes: Here is an article where they measured the concentration of Dust Mites in mattresses: http://ehp.niehs.nih.gov/members/1998/106p659-664hirsch/hirsch-full.ht ml "Sampling Procedure Carpets (1 m2) and children's mattresses (1.6 m2, covers removed) were vacuumed for 5 min with vacuum cleaners with a motor capacity of at least 800 W by residents following written instructions (study 1) or by trained field workers (study 2). Dust was collected with a sampling device (ALK, Copenhagen, Denmark) holding a cellulose filter (Filtrak GmbH Niederschlag, Germany, no. 60; 0.35 mm thick, pore size 30-40 µm), which retains 98% of particles >0.7 µm in diameter and 91% of particles >0.3-0.7 µm. Laboratory Analysis Samples were weighed and processed unsieved (allergen extraction from dust and filter paper) to allow the determination of total allergen amount. The concentration of HDM allergens Der p 1 and Der f 1 was determined with a commercial sandwich ELISA (ALK). The results were expressed as allergen concentration (microgram per gram of dust) and as amount of surface allergen (microgram per square meter). The intra-assay CV determined by the manufacturer was 4.1-19.9%. The interassay CV determined in our laboratory by positive control samples on every plate ranged between 9.2% and 16.6% (Der p 1) and 14.9% and 16.5% (Der f 1). Assay sensitivity was 3 ng/ml or 0.03 µg/g dust. " Here is a description of the "commerical sandwich ELISA" mentioned in that article: Sandwich ELISA ( Enzyme-linked Immunosorbent Assay ) The sandwich ELISA measures the amount of antigen between two layers of antibodies. The antigens to be measured must contain at least two antigenic sites, capable of binding to antibody, since at least two antibodies act in the sandwich. So sandwich assays are restricted to the quantitation of multivalent antigens such as proteins or polysaccharides. Sandwich ELISAs for quantitation of antigens are especially valuable when the concentration of antigens is low and/or they are contained in high concentrations of contaminating protein. ------------------------------------------------------------------------ http://research.cm.utexas.edu/bkitto/Kittolabpage/Protocols/Biochemistry/ sELISA.html Here is a brochure on ELISA: http://www.kpl.com/docs/techdocs/chapters%201%20-%204.pdf
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