Issue 12, 2015

Nanocapsules templated on liquid cores stabilized by graft amphiphilic polyelectrolytes

Abstract

A surfactant-free method of preparation of nanocapsules templated on liquid cores using amphiphilic graft polyelectrolytes was developed. A model photoactive copolymer, poly(sodium 2-acrylamido-2-methyl-1-propanesulfonate) with grafted poly(vinylnaphthalene) chains (PAMPS-graft-PVN) was used to stabilize toluene droplets in an aqueous emulsion. The macromolecules, due to their amphiphilic character and the presence of strong ionic groups, tend to undergo intramolecular aggregation in water but at the water–oil interface less compact conformation is preferred with PVN grafts anchoring in the oil phase and the charged PAMPS main chains residing in the aqueous phase, thus stabilizing the nanoemulsion droplets. Formation of such nanocapsules was confirmed by dynamic light scattering measurements as well as SEM and cryo-TEM imaging. Grafting density and content of the chromophores in the graft copolymers were varied in order to achieve high stability of the coated nanodroplets. It was shown that the capsules are better stabilized by the copolymers with many short hydrophobic grafts than with fewer but longer ones. Use of photoactive polyelectrolytes enabled spectroscopic investigation of the relationship between conformation of the macromolecules and stabilization of the oil-core nanocapsules. Long-term stability of the nanocapsules was achieved and further increased by multilayer shell formation using polyelectrolytes deposited via the layer-by-layer approach. The obtained capsules served as efficient nanocontainers for a hydrophobic fluorescent probe. The proposed strategy of nanocapsule preparation may be easily extended to biologically relevant polymers and applied to fabricate liquid core nanodelivery systems without the need of using low molecular weight additives which may have adverse effects in numerous biomedical applications.

Graphical abstract: Nanocapsules templated on liquid cores stabilized by graft amphiphilic polyelectrolytes

Supplementary files

Article information

Article type
Paper
Submitted
05 Jan 2015
Accepted
16 Feb 2015
First published
19 Feb 2015

Nanoscale, 2015,7, 5525-5536

Author version available

Nanocapsules templated on liquid cores stabilized by graft amphiphilic polyelectrolytes

J. Szafraniec, M. Janik, J. Odrobińska and S. Zapotoczny, Nanoscale, 2015, 7, 5525 DOI: 10.1039/C5NR00064E

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