Patent ID: 8651113

Claim:
A method for delivering a therapeutic to target cells within a body, the method comprising the following steps: preparing magnetically responsive therapeutic constructs comprising: magnetically responsive carrier nanoparticles selected from the group consisting of: (a) single-domain nanoparticles comprising magnetite and having an average particle size ranging between 1 and 50 nanometers, (b) clusters of single-domain nanoparticles comprising magnetite, the particles having an average particle size ranging between 1 and 50 nanometers, the clusters having an average cluster ranging between 5 and 1000 nanometers, and mixtures of (a) and (b); a silica coating encapsulating the single-domain nanoparticles; a silane coupling agent bonded to the silica coating and having a specific pendant functional group comprises a carboxyl group capable of selectively binding with the therapeutic; and the therapeutic chemically bonded to the silane coupling agent; wherein the silane coupling agent comprises an alkoxysilylpropyl-O-polyethylene oxide urethane containing monomer units of polyethylene glycol (PEG) terminating in an alcohol function which has been oxidized to a carboxyl group; introducing the magnetically responsive therapeutic constructs into the body; and moving the therapeutic constructs to the target cell using a controllable magnetic field generator adapted to move the carrier nanoparticles in three dimensions.