A novel aptasensor integrating the DNA rolling nanomachine and Tb/COF/KB as dual signal amplifiers for kanamycin detection in foods.

A novel aptasensor for the detection of kanamycin (KNM) was developed based on dual signal amplification through nanomaterials and DNA rolling machines. Firstly, a composite consisting of the covalent organic framework (COF), ketjen black (KB) and toluidine blue (Tb), was synthesized for signal generation. Tb molecules were loaded into the composite and combined with AuNPs to serve as tracer label. Secondly, the wDNA-loaded Fe3O4 magnetic beads (wDNA@MBs) as the DNA walking legs, with cleavage by Mg2+-driven DNAzyme, the DNA walking legs can move along the sDNA-decorated MBs surface, converting the target KNM into numerous output DNA strand, achieving sensitive amplification. With a low detection limit of 0.66 fM and a wide linear dynamic range from 10 fM to 100 nM, this aptasensor showed good results in the detection of KNM in real samples. Therefore, we envision it can provide a useful method for KNM detection in actual samples.