Facile Formation of Uniform Shell-Crosslinked Nanoparticles with Built-in Functionalities from N-Hydroxysuccinimide-Activated Amphiphilic Block Copolymers

Authors

  • Yali Li,

    1. Center for Materials Innovation, Department of Chemistry and Department of Radiology, Washington University in Saint Louis, One Brookings Drive, CB 1134, Saint Louis, MO 63130-4899 (USA)
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  • Isamu Akiba,

    1. Department of Chemical Processes and Environments Faculty of Environmental Engineering University of Kitakyushu 1-1 Hibikino, Wakamatsu, Kitakyshu 808-0135 (Japan)
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  • Simon Harrisson,

    1. Center for Materials Innovation, Department of Chemistry and Department of Radiology, Washington University in Saint Louis, One Brookings Drive, CB 1134, Saint Louis, MO 63130-4899 (USA)
    2. CSIRO Molecular and Health Technologies Locked Bag 10, Clayton South MDC, VIC 3169 (Australia)
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  • Karen L. Wooley

    Corresponding author
    1. Center for Materials Innovation, Department of Chemistry and Department of Radiology, Washington University in Saint Louis, One Brookings Drive, CB 1134, Saint Louis, MO 63130-4899 (USA)
    • Center for Materials Innovation, Department of Chemistry and Department of Radiology, Washington University in Saint Louis, One Brookings Drive, CB 1134, Saint Louis, MO 63130-4899 (USA).
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  • The authors thank Prof. S. E. Sakiyama-Elbert and Ms. N. Kohrt (Department of Biomedical Engineering) for their assistance with DLS and zeta potential measurements, and Mr. G. M. Veith (Washington University Electron Microscopy Laboratory) for assistance with TEM. This material is based upon work supported by the National Heart Lung and Blood Institute of the National Institutes of Health as a Program of Excellence in Nanotechnology (HL080729). Small-angle X-ray scattering (SAXS) measurements were carried out at the BL-40B2 station at SPring-8, Japan, with financial support by a Grant-in-aid for Young Scientists (No. 18750194) from the Japan Society for the Promotion of Science. Supporting Information is available online from Wiley InterScience or from the authors.

Abstract

An amphiphilic block copolymer, poly(methylacrylate)82-block-poly(N-(acryloyloxy)succinimide0.29-co-(N-acryloylmorpholine)0.71)155 (PMA82-b-P(NAS0.29-co-NAM0.71)155), was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and then was supramolecularly assembled into micelles in aqueous solution, followed by chemical crosslinking throughout the shell region upon the introduction of 2,2′-(ethylenedioxy)-bis(ethylamine) as a crosslinker to afford well-defined shell crosslinked nanoparticles (SCKs). The number-averaged hydrodynamic diameters of the micelles and SCKs were (17 ± 4) nm and (16 ± 3) nm, respectively, by dynamic light scattering (DLS), and (15 ± 2) nm and (13 ± 2) nm, respectively, by transmission electron microscopy (TEM). In an attempt to narrow the particle size distributions, the dodecyl trithiocarbonate chain end of the block copolymer was replaced by a 2-cyanoisopropyl moiety. Each nanoparticle system was characterized by DLS, electrophoretic light scattering (ELS), TEM, and small-angle X-ray scattering (SAXS). SAXS was of particular importance, as it provided definitive observation and quantification of shell contraction and densification upon shell crosslinking. The direct incorporation of NAS into the block copolymers during their preparation allowed for unique crosslinking chemistry to proceed with added diamino crosslinkers. The primary advantages of this system include the ability to conduct in situ synthesis of SCKs that are crosslinked directly and derivatized easily by adding nucleophilic ligands before, during, or after the crosslinking.

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