Gradient Lateral Flow Immunoassay of Human Chorionic Gonadotropin

A new format for the express method of visual semiquantitative analysis based on the principle of gradient lateral flow immunoassay with gold nanoparticles as a label is proposed. Several test bands with an increasing concentration of specific antibodies immobilized on the membrane are formed in the analytic zone of the test strip. The antigen content is semiquantitatively evaluated visually by counting the number of visible colored bands in the analytic zone. By the example of the human chorionic gonadotropin hormone, the possibility of noninstrumental semiquantitative determination of the antigen in the range from 50 to 10000 mU/mL for 5–10 min was shown in five concentration ranges: under 100, 100–300, 300–500, 500–800, and above 800 mU/mL. The developed semiquantitative express method allows visually determining the concentration range of human chorionic gonadotropin in the urine by the number of colored bands for diagnosing pregnancy and its course.