Saliva-based screening approach for Alzheimer's disease via the cell-oriented ion-sensitive field-effect transistor

Recent advanced technologies have focused on the development of simple, cost effective, and reliable diagnostic methods for diseases. The combination of improved technology and non-invasive sampling has been proposed as a new approach in medical diagnosis. Thus, we developed a screening-based biosensor with the ion-sensitive field-effect transistor (ISFET) to screen for Alzheimer's disease (AD) using the human saliva. The biosensor we developed uses a gustatory receptor (Gr5a) expressed in Drosophila Schneider 2 cells to detect the presence of sugar, particularly trehalose, in the saliva of humans. In this study, a total of six human saliva samples, of which five were obtained from AD patients and one from a normal individual without a history of AD were used. Based on the results, the response voltages generated from the human saliva of AD and that of a normal person were distinctively divided into two clusters using the Gr5a-expressed cell-oriented ISFET. This suggests that the content of sugar present in the saliva of AD and the normal person differed. Moreover, the variation of sugar detected might suggest that a sugar-based molecule such as trehalose could be a potential novel biomarker for the progression of AD. Hence, the cell-oriented ISFET developed has great prospects for use as a non-invasive screening device for AD in the near future.