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Polyoxazoline-Based Bottlebrush and Brush-Arm Star Polymers via ROMP: Syntheses and Applications as Organic Radical Contrast Agents.

ABSTRACT: The synthesis of functional poly(2-alkyl-2-oxazoline) (PAOx) copolymers with complex nanoarchitectures using a graft-through ring-opening metathesis polymerization (ROMP) approach is described. First, well-defined norbornene-terminated poly(2-ethyl-2-oxazoline) (PEtOx) macromonomers (MM) were prepared by cationic ringopening polymerization. ROMP of these MMs produced bottlebrush copolymers with PEtOx side chains. In addition, PEtOx-based branched MMs bearing a terminal alkyne group were prepared and conjugated to an azide-containing bis-spirocyclohexyl nitroxide via Cu-catalyzed azide-alkyne cycloaddition (CuAAC). ROMP of this branched MM, followed by in situ cross-linking, provided PEtOx-based brush-arm star polymers (BASPs) with nitroxide radicals localized at the core-shell interface. These PEtOx-based nitroxide-containing BASPs displayed relaxivity values on par with state-of-the-art polyethylene glycol (PEG)-based nitroxide materials, making them promising as organic radical contrast agents for metal-free magnetic resonance imaging (MRI).

SUBMITTER: Alvaradejo GG

PROVIDER: S-EPMC6615754 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Brush-First and ROMP-Out with Functional (Macro)monomers: Method Development, Structural Investigations, and Applications of an Expanded Brush-Arm Star Polymer Platform.

Project description:The efficient synthesis of complex functional polymeric nanomaterials is often challenging. Ru-initiated ring-opening metathesis polymerization (ROMP) of multivalent macromonomers followed by cross-linking to form brush-arm star (BASP) polymers enables access to well-defined nano-structures with diverse functionality. This "brush-first" method leaves active Ru in the BASP microgel core, which could potentially be used in a subsequent "ROMP-out" (RO) step to introduce further modifications to the BASP structure via the addition of (macro)monomers. Here, we study this RO approach in depth. The efficiency of RO is assessed for a variety of BASP compositions using a combination of inductively coupled plasma mass spectrometry and gel permeation chromatography. To demonstrate the modularity of the RO process, arylboronic acid-functionalized BASPs were prepared; uptake of these RO-BASPs into hypersialylated cancer cells was enhanced relative to non-functionalized BASPs as determined by flow cytometry and fluorescence microscopy. In addition, the self-assembly of miktoarm BASPs prepared via brush-first and RO with different macromonomers is demonstrated. The combination of brush-first ROMP with RO provides a simple, modular strategy for access to a wide array of functional nanomaterials.

| S-EPMC6625813 | biostudies-literature

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Tailored silyl ether monomers enable backbone-degradable polynorbornene-based linear, bottlebrush and star copolymers through ROMP.

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| S-EPMC7299178 | biostudies-literature

End-functionalized ROMP polymers for Biomedical Applications.

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Supramolecular Mimic for Bottlebrush Polymers in Bulk.

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| S-EPMC6787885 | biostudies-literature

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