An optrode system based on a competitive binding technique for fluoroimmuoassay was developed. Immunoglobulin E (IgE) was immobilized on a membrane which covered the edge of an optical fiber. The sensor was exposed to a solution containing dinitrophenylated bovine serum albumin (DNP-BSA) and then allophycocyanin conjugated DNP-BSA was added. A helium-neon (He-Ne) laser provided an excitation of the binding antigen-antibody complex. The resulting in fluorescence emission was measured using the sensing probe. The fluorescence intensity was proportional to the amount of allophycocyanin conjugated DNP-BSA in the sample. A linear relationship was obtained between the relative fluorescence intensity and the allergen concentration in the range 0~10 ng ml–1.
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