Development of propolis-loaded block copolymer micelles of superior structural stability and high loading capacity

Publication date: 8 September 2017
Source:Polymer, Volume 125
Author(s): Petar D. Petrov, Georgy Grancharov, Valeria Gancheva, Boryana Trusheva, Vassya Bankova, Christo B. Tsvetanov
We report on the efficient loading of poplar propolis into core-shell micelles based on amphiphilic poly(ethylene oxide)-block-poly(n-butyl acrylate) (PEO-b-PnBA) diblock copolymers. The copolymers comprising a hydrophilic PEO block of constant length (113 monomer units) and a soft hydrophobic PnBA block of three different lengths (53, 99 and157 monomer units) were synthesized by atom transfer radical polymerization (ATRP) of n-butyl acrylate initiated by PEO bromoisobutyrate. The study focused on fabrication of stable aqueous colloid systems characterized by complete encapsulation of all bioactive lipophilic propolis constituents with in the micellar carrier. The effects of copolymer/propolis mass ratio, copolymer composition and concentration on system characteristics were examined by dynamic light scattering (DLS), atomic force microscopy (AFM) and turbidity measurements. The results revealed that stable aqueous colloids and complete encapsulation of the lipophilic bioactive compounds into the micelles can be achieved at twofold excess of copolymer to propolis amount.

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