Polypeptide nanogels with hydrophobic moieties in the cross-linked ionic cores: synthesis, characterization and implications for anticancer drug delivery

Abstract

Polymer nanogels have gained considerable attention as a potential platform for drug delivery applications. Here we describe the design and synthesis of novel polypeptide-based nanogels with hydrophobic moieties in the cross-linked ionic cores. Diblock copolymer, poly(ethylene glycol)-b-poly(l-glutamic acid), hydrophobically modified with l-phenylalanine methyl ester moieties was used for controlled template synthesis of nanogels with small size (ca. 70 nm in diameter) and narrow particle size distribution. Steady-state and time-resolved fluorescence studies using coumarin C153 indicated the existence of hydrophobic domains in the ionic cores of the nanogels. Stable doxorubicin-loaded nanogels were prepared at high drug capacity (30 w/w%). We show that nanogels are enzymatically-degradable leading to accelerated drug release under simulated lysosomal acidic pH. Furthermore, we demonstrate that the nanogel-based formulation of doxorubicin is well tolerated and exhibit an improved antitumor activity compared to a free doxorubicin in an ovarian tumor xenograft mouse model. Our results signify the point to a potential of these biodegradable nanogels as attractive carriers for delivery of chemotherapeutics.

• Core-shell morphology
• doxorubicin
• nanogel
• PEG-b-poly(l-glutamic acid)
• phenylalanine

Acknowledgements

We would like to thank the NMR, Confocal Microscopy and Nanoimaging Core Facilities at UNMC for excellent technical assistance and Dr Daria Alakhova for the help in the preparation of illustration for this paper.