Active Targeting

In opposition to the passive accumulation of the nano-particles at a target site, active targeting aims to direct long-circulating particles to a designated but accessible target. For this, ligands that specifically bind to surface epitopes or receptors located on the target have to be coupled to the surface of the carriers. However, only few examples in the literature deal with this type of targeting.

Functionalized nanospheres were formed by using a novel copolymer, poly(amino poly(ethylene glycol) cyanoacrylate-co-hexadecyl cyanoacrylate) [125]. Folic acid was conjugated to these macromolecules via the PEG terminal amino groups. The specific interaction between the nanospheres and the folate-binding protein was confirmed by surface plasmon resonance.

Recently, a strategy to couple under mild conditions several different ligands at the nanospheres' surface was proposed [126]. This could be useful for complex lock-and-key targeting. For this, biotin was first coupled to the terminus of PEG chains of preformed PEG-PCL copolymers. Biotiny-lated lectins were coupled to the nanoparticles, after avidin addition. The concept was validated with biotinylated wheat germ agglutinin; its coupling to the nanospheres' surface dramatically enhanced the interaction with Caco2 cells.

0 0

Post a comment