Encapsulation of nanoparticles with multifunctional, cross-linkable diblock copolymers for biomedicine

C. Schmidtke, J. Ostermann, H. Tran, E. Pöselt, H. Kloust, J. Niehaus, S. Becker, A. Kreuziger, K. Werner, A. Pietsch, H. Weller
University of Hamburg, DE

Keywords: quantum dots, nanoparticles, diblock copolymer, functionalization, phase transfer, imaging, tumor targeting

Summary:

We would like to present a micellular encapsulation method for nanoparticles (quantum dots, iron oxides, gold) which is based on a ligand exchange procedure of native ligands with a prepolymer poly(isoprene)-diethylentriamine (PI-N3) and subsequent ligand addition with poly(isoprene)-b-poly(ethylene glycol) diblock copolymer (PI-b-PEG). As previously reported ligand systems are usually based on self-organization by hydrophobic effects and/or coordinative bonds. Here, both effects were combined and expanded to include the cross-linkage of the poly(isoprene) moiety. This leads to unique stability in aqueous media with fluorescence quantum efficiencies up to 55% and ensures rigidity against biodegradation. PI-b-PEG diblock copolymer encapsulated NPs are non-toxic and were used for antibody-mediated imaging of tumors in vivo. The use of the diblock copolymer allows the functionalization at different stages: a) prior to the ligand addition by terminating the polymerization or after the polymerization (pre-assembly) and b) after the ligand addition (post-assembly).