Core-satellite assemblies and exonuclease assisted double amplification strategy for ultrasensitive SERS detection of biotoxin.

In this work, core-satellite assemblies and exonuclease assisted double amplification strategy is developed to produce surface-enhanced Raman scattering (SERS) biosensor towards ultrasensitive detection of biotoxin. In the presence of target molecules, the exonuclease III (Exo III) assisted efficient recycling amplification provides an excellent pathway for the fabrication of core-satellite SERS sensor. Briefly, the proposed strategy includes the following double amplifications: (i) Exo III induced target-related signal amplification; (ii) core-satellite assemblies assisted formation of SERS "hot-spots" induced signal amplification. To show the applicability of the suggested strategy, the detection of ochratoxin A (OTA), one of the most toxic and widely distributed biotoxin, is demonstrated as an example. The results show that the limit of detection (LOD) of OTA is 0.83 fg mL-1 (S/N = 3). On the basis of the DNA aptamer induced specific target recognition, hence our sensing strategy is easy to be expended to the ultrasensitive detection of other targets, e.g., DNAs, RNAs, and other molecules that have corresponding DNA aptamers.