The MNPs are coated with the second target-specific DNA probe (2pDNA) that can recognize the other end of the target gene.
After binding the nanoparticles with the target DNA, the following sandwich structure is formed: MNP-2pDNA/tDNA/1pDNA-AuNP-bDNA-NTs. A magnetic field is applied to separate the sandwich structure from the unreacted materials.
Because the AuNPs have a large number of nanoparticle tracers per DNA probe binding event, there is substantial amplification.