Immunological Helicobacter pylori urease analyzer based on ion-sensitive field effect transistor

Immunological Helicobacter pylori (H. pylori) urease analyzer (HPUA), based on a solid-phase tip coated with a monoclonal antibody toward H. pylori's urease and ion-sensitive field effect transistor (ISFET), was developed. In this system, H. pylori urease adsorbed on the solid-phase tip, after a 15-min immunological reaction with gastric mucus sample solution, was measured with a urease analyzer composed of a flow-through cell for urea solution equipped with the measuring and reference ISFETs. The pH change (ΔpH) of urea solution after 55 s of the enzymatic reaction inside the tip was measured by withdrawing about 1 μl of the urea solution toward the upstream of the tip, where the measuring ISFET is installed. It was confirmed that the present system could detect 0.2 mIU/ml of H. pylori urease. Clinical evaluations of the system were performed for 119 patients using urea breath test (UBT) as a gold standard, resulting in the sensitivity = 33/36 = 92% and specificity = 81/83 = 98%, respectively.