Novel RAFT amphiphilic brush copolymer steric stabilisers for cubosomes: Poly(octadecyl acrylate)-block-poly(polyethylene glycol methyl ether acrylate)

Josephine Chong, Xavier Mulet, Almar Postma, Daniel J Keddie, Lynne J Waddington, Benjamin James Boyd, Calum John Drummond

Research output: Contribution to journalArticleResearchpeer-review

24 Citations (Scopus)

Abstract

Copolymers, particularly Pluronics?, are typically used to sterically stabilise colloidal nanostructured particles composed of a lyotropic liquid crystalline bicontinuous cubic phase (cubosomes). There is a need to design and assess new functionalisable stabilisers for these colloidal drug delivery systems. Six amphiphilic brush copolymers, poly(octadecyl acrylate)-block- poly(polyethylene glycol methyl ether acrylate) (P(ODA)-b-P(PEGA-OMe)), synthesised by reversible addition-fragmentation chain transfer (RAFT), were assessed as novel steric stabilisers for cubosomes. It was found that increasing the density of PEG on the nanostructured particle surface by incorporating a PEG brush design (i.e., brush copolymer), provided comparable and/or increased stabilisation effectiveness compared to a linear PEG structure, Pluronic? F127, which is extensively used for steric stabilisation of cubosomes. Assessment was conducted both prior to and following the removal of the dodecyl trithiocarbonate end-group, by free radical-induced reduction. The reduced (P(ODA)-b-P(PEGA-OMe) copolymers were more effective steric stabilisers for phytantriol and monoolein colloidal particle dispersions than their non-reduced analogues. High throughput characterisation methodologies, including an accelerated stability assay (ASA) and synchrotron small angle X-ray scattering (SAXS), were implemented in this study for the rapid assessment of steric stabiliser effectiveness and lyotropic liquid crystalline phase identification. Phytantriol cubosomes stabilised with P(ODA)-b-P(PEGA-OMe) copolymers exhibited a double diamond cubic phase (QD2), whilst monoolein cubosomes exhibited a primitive cubic phase (QP2), analogous to those formed using Pluronic? F127.
Original languageEnglish
Pages (from-to)6666 - 6676
Number of pages11
JournalSoft Matter
Volume10
Issue number35
DOIs
Publication statusPublished - 2014

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