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Colloids Surf B Biointerfaces. 2016 May 1;141:318-326. doi: 10.1016/j.colsurfb.2016.01.044. Epub 2016 Jan 28.

Nanomicelles based on a boronate ester-linked diblock copolymer as the carrier of doxorubicin with enhanced cellular uptake.

Author information

1
Shanghai Engineering Research Centre of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, PR China.
2
College of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, PR China.
3
The Commonwealth Scientific and Industrial Research Organisation, Bayview Ave, Bag 10, Clayton South, Melbourne, Victoria 3169, Australia.
4
Shanghai Engineering Research Centre of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, PR China. Electronic address: jhyu@sist.ecnu.edu.cn.

Abstract

This study sought to develop a new type nanomicelle based on boronate ester-linked poly(ethylene glycol)-b-poly(benzyl glutamate) (PEG-BC-PBLG) diblock copolymer as the carrier of doxorubicin (Dox) to achieve acid-induced detachment of PEG shells and subsequent boronic acid-mediated enhanced endocytosis. In vitro studies revealed that the PEG-BC-PBLG copolymer was stable in neutral solutions but tend to hydrolysed under acidic conditions, which was attributed to the acid-sensitive properties of boronate ester bonds. The formation of PEG-BC@PBLG micelles was confirmed based on critical micelle concentration (CMC), particle size, and morphology observations. It was observed that these micelles were spherical with an average particle size of approximately 80nm, as measured by dynamic laser scattering (DLS), suggesting their passive targeting to tumour tissue and endocytosis potential. Dox-loaded PEG-BC@PBLG micelles (PEG-BC@PBLG·Dox) showed sustained drug release profiles over 9h, and their cumulative drug release was dependent on the pH value of the environment. Remarkably, cellular uptake ability of PEG-BC@PBLG micelles was found to be higher than that of non-boronate ester-linked PEG@PBLG micelles due to boronic acid-mediated endocytosis, as revealed by confocal laser scanning microscopy (CLSM) imaging of fluorescein isothiocyanate (FITC) green-conjugated micelles, thereby providing higher cytotoxicity against HepG2 cells. The antitumour activity and toxicity of PEG-BC@PBLG·Dox micelles in vivo were evaluated in BLAB/c mice against HepG2 cell-derived tumours. Compared with Dox, PEG-BC@PBLG·Dox showed reduced toxicity, whereas its tumour growth inhibition rate was 17% higher than that of free Dox. These results indicate the great potential of PEG-BC@PBLG micelles as the carrier of various lipophilic anticancer drugs with improved anti-tumour efficacy.

KEYWORDS:

Acid-induced degradation; Boronate ester; Enhanced endocytosis; HepG2 cells; Nanomicelle

PMID:
26874117
DOI:
10.1016/j.colsurfb.2016.01.044
[Indexed for MEDLINE]

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