Abstract
In this research, the direct detection of DNA, RNA and proteins in physiological salt concentration by FET based biosensor has been investigated systematically. For the CVD biomarkers, miR-126, miR-21, miR-208a and CRP have been chosen. We have introduced a novel biosensor structure which can provide promising result with low detection limit and high resolution. The new biosensor structure with the electric-double layer structure can solve the Debye length problem which has been existed in FET sensors for years. The FET made by AlGaN/GaN HEMT having high transconductance gain, can significantly improve the S/N ratio and sensitivity. The sensor has shown its low detection limit of 1fM in DNA detection initially. Then, with the six, two and one mismatched base of DNA signal comparison, the specificity of the sensor is also proven. Furthermore, the three miR-126, miR-21 and miR208a RNA CVD biomarkers samples in TE buffer are also measured in different concentrations. The calibration curves of the three RNA sequences are all with appreciable increasing trend in total charge. Finally, the CRP quantitatively detection is also demonstrated in low concentrations and get the extremely low detection limit of 0.21 mg/L in human serum samples.