Synthesis of Hollow Responsive Functional Nanocages Using a Metal–Ligand Complexation Strategy

Abstract

A metal–ligand complexation strategy using ruthenium−terpyridine interactions was utilized for the facile synthesis of amphiphilic block copolymers which were self-assembled into spherical micelles and stabilized throughout their shell to afford well-defined nanoparticles. The labile metal–ligand bond at the nanoparticle core–shell interface was then readily broken to enable excavation to afford hollow completely hydrophilic nanocages which can no longer sequester hydrophobic small molecules. These nanocages also demonstrated pH responsiveness and could be further functionalized by the reintroduction of metals.

Crosslinked polymer nanocapsules

“…This synthetic strategy was adopted and further extended by several other groups using non‐covalently connected micelles to simplify the core removal procedure. O'Reilly and co‐workers prepared non‐covalently connected micelles from amphiphilic block metallopolymers with block junctions formed through metal–ligand coordination, and subsequently transformed them into CPNCs by shell‐crosslinking, followed by ligand exchange and dialysis to remove the cores . Jiang and co‐workers synthesized CPNCs by the preparation of hydrogen‐bonding connected polymer micelles using two homopolymers carrying complementary hydrogen‐bond forming groups in a selective solvent, followed by shell‐crosslinking and core removal using a good solvent .…”

Using Metallo‐Supramolecular Block Copolymers for the Synthesis of Higher Order Nanostructured Assemblies

“…In our initial investigations, we used a bis-terpyridine Ru(II) symmetrically linked amphiphilic block copolymer similar to those reported previously. [46] Firstly, two terpyridine end functionalized polymers were synthesized: a hydrophobic PS 120 -[ block and a hydrophilic poly(acrylic acid) Figure 8. The amphiphilic metallo-supramolecular diblock copolymer PFS-[Ru]-PEO and the selfassembled diblock copolymer cylinders by TEM.…”

“…(i) Self-assembly of bis-terpyridine Ru(II) linked diblock to give micelles, (ii) crosslinking to give nanoparticles, and (iii) breaking of the bis-terpyridine-Ru(II) bonds and PS core hollowing in THF/water, to give terpyridine functionalized hollow nanocages. [46] Macromol. Rapid Commun.…”

“…[39][40][41][42][43][44] Moreover, in recent years, researchers have begun to pre-design and manipulate such metallo-supramolecular block copolymers to target specific nanostructures whereby a key design feature in their synthesis is utilized after self-assembly has occurred; viz, the supramolecular linkage can be selectively cleaved to remove the attached polymer blocks, thus producing novel functional architectures from tailor made parent self-assembled structures. [31,[45][46][47][48] In this feature article, we will provide a brief introduction to the field of main chain metallo-supramolecular block copolymers and evaluate recent literature on the topic of their specific design to undergo self-assembly to form tuneable and stimuli responsive higher order structures. We will also discuss their possible future development for use in novel applications which utilize these key design features.…”

Bowl- and porous sphere-shaped supramolecular assemblies and their application as templates for confined assembly of gold nanoparticles

“…Supramolecular copolymers, in which the polymer chains are held together via reversible, noncovalent bonds, offer an alternative strategy to build polymeric assemblies. [24][25][26] Electrostatic interaction [27][28][29][30] has certain advantages among the conventional noncovalent bonds, including hydrogen-bond, 31 metal-ligand interactions, 32 and host-guest interaction etc. 33 First of all, certain block copolymers which can not be obtained due to synthesis difficulties may be brought into reality by taking advantage of the supramolecular chemistry based on the electrostatic interaction.…”