LUMINESCENT OXYGEN CHANNELING IMMUNOASSAY - MEASUREMENT OF PARTICLE BINDING-KINETICS BY CHEMILUMINESCENCE

A method for monitoring formation of latex particle pairs by chemiluminescence is described. Molecular oxygen is excited by a photosensitizer and an antenna dye that are dissolved in one of the particles. (1) Delta(g)O(2) diffuses to the second particle and initiates a high quantum yield chemiluminescent reaction of an olefin that is dissolved in it. The efficiency of (1) Delta(g)O(2) transfer between particles is approximate to 3.5%. The technique permits real-time measurement of particle binding kinetics. Second-order rate constants increase with the number of receptor binding sites on the particles and approach diffusion control. By using antibody-coated particles, a homogenous immunoassay capable of detecting approximate to 4 amol of thyroid-stimulating hormone in 12 min was demonstrated. Single molecules of analyte produce particle heterodimers that are detected even when no larger aggregates are formed.