Chemiluminescence and colorimetric reactions

All integrated sensors based on an interaction between the analyte and reagent (neither of which is used in a retained form) and regeneration of the latter rely on chemiluminescent reactions involving electroregeneration of the reagent or a quenching phenomenon. On the other hand, absorptiometric and reflectometric sensors of this type use colorimetric acid-base indicators supported on a suitable material. 

This paper presents analysis methods for compounds fo defermine fheir general biological acfivity. Characferisfics of the methods in model systems using different antioxidant reaction mechanisms are also described. Both colorimetric methods and those with fluorometric detection as well as chemiluminescence testing are included. 

Colorimetric assays are commonly used in molecular biology and biotechnology laboratories for determining protein concentrations because the procedures and their instrumentation requirements are simple. Two forms of assays are used. The first involves reactions between the protein and a suitable chemical to yield a colored, fluorescent, or chemiluminescence product. Second, a colored dye is bound to the protein and the absorbance shift is observed. Disadvantages of both these methods include limited sensitivity at below 1 pg/mL, interferences from buffers, and unstable chromophores (Jain et al. 1992). 

Methods for meat species identification based on DNA analysis benefit from the heat stability of the DNA molecule and its high specificity. Originally, DNA methods consisted of immobilization of partially purified and denatured DNA, extracted from the meat product sample, on a nylon membrane, followed by hybridization of a species-specific segment of labeled (colorimetric, fluorescent, or chemiluminescent) DNA with any complementary sequences of DNA present on the membrane. More recently, a DNA amplification method - the polymerase chain reaction - has been used, but this is a relatively expensive and technically demanding technique. 

Vlieger AM, Medenblik AM, van Gijlswijk RP, Tanke HJ, van der Ploeg M, Gratama JW, and Raap AK (1992) Quantitation of polymerase chain reaction products by hybridization-based assays with fluorescent, colorimetric, or chemiluminescent detection. Analytical Biochemistry 205(1) 1-7. 

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