title: Amphiphilic, cross-linkable diblock copolymers for multifunctionalized nanoparticles as biological probes.
abstract: Nanoparticles (NPs) play an increasingly important role in biological labeling and imaging applications. However, preserving their useful properties in an aqueous biological environment remains challenging, even more as NPs therein have to be long-time stable, biocompatible and nontoxic. For in vivo applications, size control is crucial in order to route excretion pathways, e.g. renal clearance vs. hepato-biliary accumulation. Equally necessary, cellular and tissue specific targeting demands suitable linker chemistry for surface functionalization with affinity molecules, like peptides, proteins, carbohydrates and nucleotides. Herein, we report a three stage encapsulation process for NPs comprised of (1) a partial ligand exchange by a multidentate polyolefinic amine ligand, PI-N3, (2) micellar encapsulation with a precisely tuned amphiphilic diblock PI-b-PEG copolymer, in which the PI chains intercalate to the PI-N3 prepolymer and (3) radical cross-linking of the adjacent alkenyl bonds. As a result, water-soluble NPs were obtained, which virtually maintained their primal physical properties and were exceptionally stable in biological media. PEG-terminal functionalization of the diblock PI-b-PEG copolymer with numerous functional groups was mostly straightforward by chain termination of the living anionic polymerization (LAP) with the respective reagents. More complex affinity ligands, e.g. carbohydrates or biotin, were introduced in a two-step process, prior to micellar encapsulation. Advantageously, this pre-assembly approach opens up rapid access to precisely tuned multifunctional NPs, just by using mixtures of diverse functional PI-b-PEG polymers in a combinatorial manner. All constructs showed no toxicity from 0.001 to 1 μM (particle concentration) in standard WST and LDH assays on A549 cells, as well as only marginal unspecific cellular uptake, even in serum-free medium.
authors.affiliation: Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany. schmidtke@chemie.uni-hamburg.de
authors.forename: Christian
authors.initials: C
authors.lastname: Schmidtke
authors.forename: Elmar
authors.initials: E
authors.lastname: Pöselt
authors.forename: Johannes
authors.initials: J
authors.lastname: Ostermann
authors.forename: Andrea
authors.initials: A
authors.lastname: Pietsch
authors.forename: Hauke
authors.initials: H
authors.lastname: Kloust
authors.forename: Huong
authors.initials: H
authors.lastname: Tran
authors.forename: Theo
authors.initials: T
authors.lastname: Schotten
authors.forename: Neus G
authors.initials: NG
authors.lastname: Bastús
authors.forename: Robin
authors.initials: R
authors.lastname: Eggers
authors.forename: Horst
authors.initials: H
authors.lastname: Weller
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry* / Q000633:toxicity
chemical_list: D001672:Biocompatible Materials; D011108:Polymers; D011092:Polyethylene Glycols