Patent ID: 6979466

Claim:
A nanoscale particle comprising an iron oxide-containing core and at least two shells surrounding said core, and at least one pharmacologically active species, wherein (1) an innermost shell adjacent to the core is a shell that (a) comprises groups that are positively charged or positively chargeable and (b) is degraded by a human or animal body tissue at such a low rate that adhesion of the core surrounded by the innermost shell to the surface of a cell through the positively charged or positively chargeable groups and incorporation of the core into an interior of the cell are possible, (2) one or more outer shells comprise at least one species that (a) comprises neutral or negatively charged groups so that the nanoscale particle has an overall neutral or negative charge from an outside of the particle and (b) is degraded by the human or animal body tissue to expose an underlying shell or shells at a rate which is higher than that of the innermost shell but is still low enough to ensure a sufficient distribution of a plurality of nanoscale particles within a body tissue that has been infiltrated therewith; and (3) the at least one pharmacologically active species is linked to the innermost shell.