Formation and Degradation
of Layer-by-Layer-Assembled
Polyelectrolyte Polyrotaxane Capsules
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Abstract
We report the preparation of degradable capsules via
layer-by-layer
assembly using polyelectrolyte (PE) polyrotaxanes (PRXs). The PRX
capsules were prepared by the sequential deposition of PRXs onto silica
particles followed by the dissolution of the silica cores. The colloidal
stability of the PRX capsules that are formed depends on the salt/buffer
solution used in the assembly process. Various salt/buffer combinations
were examined to avoid aggregation of the core–shell particles
during PRX assembly and core dissolution. Using appropriate assembly
conditions, we prepared colloidally stable, robust capsules. PRX capsules
consisting of eight layers of PE PRXs had a wall thickness of ∼15
nm. The degradation of the PRX capsules was demonstrated through the
disassembly of the PE PRXs using glutathione, which cleaves the disulfide
bonds linking the end-capping groups of the PE PRXs. Given the supramolecular
noncovalent structure of PRXs and their adjustable properties, it
is expected that PRXs will be used as building blocks for assembling
advanced capsules with unique and tailored properties