Nanoparticles can achieve targeting through multiple mechanisms:
1. Passive Targeting: This relies on the natural distribution of nanoparticles in the body. For instance, tumors often have leaky vasculature, allowing nanoparticles to accumulate more in these areas, a phenomenon known as the Enhanced Permeability and Retention (EPR) effect.
2. Active Targeting: Involves functionalizing nanoparticles with specific ligands, antibodies, or peptides that bind to unique receptors or molecules overexpressed on the target cells. This can significantly increase the selectivity and binding affinity of the nanoparticles to the target site.
3. Magnetic Targeting: Uses external magnetic fields to direct magnetic nanoparticles to a specific location. This method is advantageous in guiding nanoparticles through biological barriers and enhancing their concentration at the target site.
