Targeting strategies using gold nanoparticles for efficient drug delivery

The conjugation of drug molecules to the surface of gold nanoparticles can allow their passive or active targeting to specific sites in the body. Passive targeting is achieved by utilizing the enhanced permeability and retention effect that is observed for solid tumors, and some types of infections and injuries. Active targeting is achieved by the co-conjugation of targeting molecules to the gold nanoparticles that are able to recognize and bind specific proteins and receptors on the surface of cells. Active targeting is most effective when the cell proteins and receptors are only expressed or overexpressed on specific cell types. Molecules used in active targeting of gold nanoparticles include small molecules, peptides and proteins, and aptamers. Active targeting of gold nanoparticles can also be achieved when the particles contain an iron oxide core which is susceptible to magnetic fields.