Ultrasound-accelerated immunoassay, as exemplified by enzyme immunoassay of choriogonadotropin

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 30; no. 9; p. 1446
• Main Authors: Chen, R, Weng, L, Sizto, N C, Osorio, B, Hsu, C J, Rodgers, R, Litman, D J
• Format: Journal Article
• Language: English
• Published: England 01-09-1984
• Subjects: Chorionic Gonadotropin - analysis; Chorionic Gonadotropin - urine; Enzymes, Immobilized; Female; Glucose Oxidase; Hot Temperature; Humans; Immunoenzyme Techniques; Kinetics; Male; Pregnancy; Reagent Strips; Sonication; Ultrasonics
• ISSN: 0009-9147
• DOI: 10.1093/clinchem/30.9.1446

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.