Single-walled carbon nanotubes based quenching of free FAM-aptamer for selective determination of ochratoxin A

► Single-walled carbon nanotubes in combination with aptamer can detect ochratoxin A. ► Ochratoxin A induces the switching of the aptamer to antiparallel G-quadruplex. ► The G-quadruplex cannot be wrapped onto the single-walled carbon nanotubes. ► Low concentration of ochratoxin A can be detected without any coating materials.