Single-walled carbon nanotube chemoresistive label-free immunosensor for salivary stress biomarkers.

The present work is focused on the development, analytical characterization and evaluation of selective and sensitive SWNT-chemiresistor immunosensor for the label-free detection of salivary α-amylase (SAA). SWNTs were aligned to bridge lithographically patterned gold microelectrodes using AC dielectrophoresis followed by functionalization with anti-SAA antibodies. The nano-immunosensors exhibited excellent sensitivity over the clinically relevant range (19 to 308 U ml(-1)) with a limit of detection (LOD) of 6 µg ml(-1) (0.6 U ml(-1)) and 7.8 µg ml(-1) (0.78 U ml(-1)) in phosphate buffer and artificial saliva, respectively, and no interference from other components of saliva. This label-free nano-immunosensor technology has potential application in clinical diagnosis for stress biomarkers expressed in human saliva at the point-of-care.