Electrical detection of VEGFs for cancer diagnoses using anti-vascular endotherial growth factor aptamer-modified Si nanowire FETs

We report the real-time, label-free and electrical detection of vascular endotherial growth factor (VEGF) for cancer diagnosis using anti-VEGF aptamer-modified Si nanowire field-effect transistors (SiNW-FETs). Specifically, the high quality single-crystalline SiNWs of both n-type and p-type characters were surface modified with the covalent immobilization of anti-VEGF aptamers, and they were turned into SiNW-FET biosensors for the VEGF detection. We show that the VEGF molecules consistently act on the gate dielectrics of both n-type and p-type SiNW-FETs as electrically positive point-charges; their recognition to anti-VEGF aptamers depletes (accumulates) the charge carriers in the p-type (n-type) SiNW-FETs and thus decreases (increases) the detection currents. The detection limit for VEGFs in this study was determined as 1.04 nM and 104 pM for the cases of n-type and p-type SiNW-FETs, respectively.