The invention is applicable to the technical field of biological detection, and provides a confinement effect activated nano-
machine composition and a preparation method and application thereof.The nano-
machine composition comprises a nano-
machine I and a nano-machine II, the nano-machine I takes gold nanoparticles as a core, the surface of the nano-machine I is modified with a binding chain, a spacer chain and
circular DNA connected with the spacer chain, and the nano-machine II takes gold nanoparticles as a core. The
circular DNA comprises a connecting region, a nano machine I binding region complementary to a spacer chain, a
signal generating region and a nano machine II binding region; the nano machine II takes magnetic nano particles as a core, and the surface of the nano machine II is modified with a primer chain and an
aptamer chain; the primer chain comprises a sequence complementary to the nano machine II binding region, and is only paired with the nano machine II binding region under a confinement condition and starts a rolling circle amplification reaction. According to the method, accurate co-localization triggering multi-stage
signal amplification is realized on the surface of a target through a dual recognition strategy, and rapid, ultra-sensitive, high-specificity and stable
field detection on the food-borne
pathogenic bacteria can be realized by combining magnetic capture and enrichment.