Ultrasensitive in Situ Label-Free DNA Detection Using a GaN Nanowire-Based Extended-Gate Field-Effect-Transistor Sensor

摘要

In this study, we have successfully demonstratednthat a GaN nanowire (GaNNW) based extended-gate fieldeffect-ntransistor (EGFET) biosensor is capable of specific DNAnsequence identification under label-free in situ conditions. Ournapproach shows excellent integration of the wide bandgapnsemiconducting nature of GaN, surface-sensitivity of the NWstructure,nand high transducing performance of the EGFETdesign.nThe simple sensor-architecture, by direct assembly of assynthesizednGaNNWs with a commercial FET device, cannachieve an ultrahigh detection limit below attomolar level concentrations: about 3 orders of magnitude higher in resolution thannthat of other FET-based DNA-sensors. Comparative in situ studies on mismatches (“hotspot” mutations related to human p53ntumor-suppressor gene) and complementary targets reveal excellent selectivity and specificity of the sensor, even in the presence ofnnoncomplementary DNA strands, suggesting the potential pragmatic application in complex clinical samples. In comparison withnGaN thin film, NW-based EGFET exhibits excellent performance with about 2 orders higher sensitivity, over a wide detection range,n10-19-10-6 M, reaching about a 6-orders lower detection limit. Investigations illustrate the unique and distinguished feature ofnnanomaterials. Detailed studies indicate a positive effect of energy band alignment at the biomaterials-semiconductor hybridninterface influencing the effective capacitance and carrier-mobility of the system.