Human chorionic gonadotropin interactions with immobilized anti-hCG studied by quartz-crystal microbalance with dissipation monitoring.

Previous studies have found that commercial human pregnancy tests are often too insensitive to function to their advertised >99% accuracy. Improper orientation of proteins used for recognition of ligands in sensors can often prevent the binding site from being available to the ligand, thereby decreasing sensor sensitivity. We have developed a simple method for the immobilization of anti-human chorionic gonadotropin on a sensor surface that maximizes its sensitivity by ensuring ligand binding sites are exposed and densely packed. This surface also has an improved regenerative capacity over previously reported human chorionic gonadotropin sensors, retaining 99% of initial sensitivity after six regeneration cycles with 8M urea.