Patent ID: 8486722

Claim:
A sensing method for biopolymers by detecting the magnetic signal generated from a labeled biopolymer under AC magnetic field with the use of thermo-responsive magnetic nano particles as label, comprising the steps of; using the thermo-responsive magnetic nano particles having a critical solution temperature across which the particles have the ability to aggregate or disperse with cooling or heating; binding a ligand for a target biopolymer to said thermo-responsive magnetic nano particles; labeling the target biopolymer in solution with said thermo-responsive magnetic nano particles using a biopolymer reaction; adding ligand free thermo-responsive magnetic nano particles; keeping the solution temperature at which said thermo-responsive magnetic nano particles aggregate; applying AC magnetic field after aggregating the thermo-responsive magnetic nano particles and enlarging the aggregate of said thermo-responsive magnetic nano particles; and obtaining a larger magnetic signal at the time of measurement as compared with the magnetic signal obtained when said ligand free thermo-responsive magnetic nano particles are not added.