title: Ultrasound-accelerated immunoassay, as exemplified by enzyme immunoassay of choriogonadotropin.
abstract: The rate-limiting step in many solid-phase immunoassays is associated with the slow kinetics of binding of macro-molecular antigen and conjugate to the immobilized phase. We demonstrate that the use of ultrasonic energy to enhance mass transport across liquid/solid interfaces can dramatically accelerate antigen binding to immobilized antibodies. We use an ultrasound-accelerated procedure with an enzyme-channelling test strip containing glucose oxidase and specific antibody to the alpha-subunit of human choriogonadotropin (HCG) co-immobilized onto a cellulose support. A horseradish peroxidase conjugate of monospecific antibody to the beta-subunit of HCG is used in the liquid phase to complete the immune "sandwich." Use of ultrasound to accelerate binding and of enzyme channelling to eliminate wash steps result in a simple two-incubation protocol by which 25 int. units of urinary HCG per liter can be detected visually in less than 20 min of assay time.
mesh_terms: D006063:Chorionic Gonadotropin / Q000032:analysis* / Q000652:urine; D004800:Enzymes, Immobilized; D005260:Female; D005949:Glucose Oxidase; D006358:Hot Temperature; D006801:Humans; D007124:Immunoenzyme Techniques; D007700:Kinetics; D008297:Male; D011247:Pregnancy; D011934:Reagent Strips; D013010:Sonication; D014465:Ultrasonics
chemical_list: D006063:Chorionic Gonadotropin; D004800:Enzymes, Immobilized; D011934:Reagent Strips; D005949:Glucose Oxidase