Hollow Block Copolymer Nanoparticles through a Spontaneous One-step Structural Reorganization

Abstract

The spontaneous one-step synthesis of hollow nanocages and nanotubes from spherical and cylindrical micelles based on poly(acrylic acid)-b-polylactide (P(AA)-b-P(LA)) block copolymers (BCPs) has been achieved. This structural reorganization, which occurs simply upon drying of the samples, was elucidated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). We show that it was necessary to use stain-free imaging to examine these nanoscale assemblies, as the hollow nature of the particles was obscured by application of a heavy metal stain. Additionally, the internal topology of the P(AA)-b-P(LA) particles could be tuned by manipulating the drying conditions to give solid or compartmentalized structures. Upon re-suspension, these reorganized nanoparticles retain their hollow structure and can be display significantly enhanced loading of a hydrophobic dye compared to the original cylinders.

Holistic Assessment of Covalently Labeled Core–Shell Polymeric Nanoparticles with Fluorescent Contrast Agents for Theranostic Applications

“…), but has been largely underutilized in the evaluation of nanoparticle- based optical contrast agents consisting of dyes conjugated to polymeric materials. 25–28 …”

The pH induced vesicle to micelle morphology transition of a THP‐protected polymer

“…The application of pH as a stimulus can cause a reversible change within the polymer, i.e., the protonation of amine units to render them hydrophilic, or can cause an irreversible chemical change such as the removal of a protecting group. Protected acid monomers have previously been utilized in the preparation of otherwise synthetically challenging amphiphilic block copolymers …”

“…Tetrahydropyranyl acrylate (THPA) is a protected acid monomer that has been shown to be polymerizable by RAFT polymerization techniques and can be deprotected either thermally or through the use of acetic acid . As the THPA deprotection is acid catalyzed, the reaction can be considered to be self‐catalytic and has been shown to be very efficient under mild conditions.…”

Functionalized Stimuli-Responsive Nanocages from Photocleavable Block Copolymers

“…16 Methodologies involving the self-assembly of copolymers into core−shell structures combined with the migration of the core forming chains into the corona were recently developed. 17,18 Other methodologies involve the self-assembly of copolymer precursors into a core−shell structure combined with the extraction 19−22 or the degradation 4,23−25 of the core forming polymer.…”

“…16 Methodologies involving the self-assembly of copolymers into core−shell structures combined with the migration of the core forming chains into the corona were recently developed. 17,18 Other methodologies involve the self-assembly of copolymer precursors into a core−shell structure combined with the extraction 19−22 or the degradation 4,23−25 of the core forming polymer.Although this last method allows the production of responsive nanocages, the control of the nanocage internal wall functionality is not always trivial. 20 To solve this issue and obtain nanocages with well-defined chemical functionalities, O'Reilly and co-workers developed a methodology based on supramolecular copolymers.…”