A fluorescence and surface-enhanced Raman scattering dual-mode aptasensor for rapid and sensitive detection of ochratoxin A

A fluorescence and surface-enhanced Raman scattering (FL-SERS) dual-mode aptasensor was established for sensitive and rapid detection of Ochratoxin A (OTA). This aptasensor was assembled by the hybridization of OTA aptamer (OTA Apt) modified gold nanostars (Apt-AuNSs) and Cy3 modified complementary DNA functionalized gold nanospheres (cDNA-AuNPs). The aptasensor displays a low FL signal due to the proximity of Cy3 to AuNSs, and a high SERS signal due to the “hot spot” effect generated by the nano-gap between AuNSs and AuNPs. In the presence of OTA, the preferential combination of OTA Apt and OTA results in a low SERS signal. Meanwhile, cDNA-AuNPs are released from the hybrid complex, leading to the recovery of the FL signal. The aptasensor has a low detection limit of 0.17 ng/mL (the detection range is 1–100 ng/mL) in FL mode and 1.03 pg/mL (the detection range is 5–250 pg/mL) in SERS mode. Furthermore, this aptasensor exhibits high specificity and good interferent resistance, which can discriminate OTA from other mycotoxins . Moreover, this aptasensor can be used for OTA detection in coffee and wine samples with good recovery rates. Unlike single-signal aptasensors, this dual-mode aptasensor holds exquisite properties such as high reliability, great detection flexibility and good anti-interference ability.