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Assembly and Characterization of Polyelectrolyte Complex Micelles
Published on: March 2, 2020
Polymeric Micelles Loading Proteins through Concurrent Ion Complexation and pH-Cleavable Covalent Bonding for In Vivo
Anqi Tao1, George Lo Huang1, Kazunori Igarashi2
1Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Abstract:
Protein drugs have great potential as targeted therapies, yet their application suffers from several drawbacks, such as instability, short half-life, and adverse immune responses. Thus, protein delivery approaches based on stimuli-responsive nanocarriers can provide effective strategies for selectively enhancing the availability and activation of proteins in targeted tissues. Herein, polymeric micelles with the ability of encapsulating proteins are developed via concurrent ion complexation and pH-cleavable covalent bonding between proteins and block copolymers directed to pH-triggered release of the protein payload. Carboxydimethylmaleic anhydride (CDM) is selected as the pH-sensitive moiety, since the CDMamide bond is stable at physiological pH (pH 7.4), while it cleaves at pH 6.5, that is, the pathophysiological pH of tumors and inflammatory tissues. By using poly(ethylene glycol)-poly(l-lysine) block copolymers having 45% CDM addition, different proteins with various sizes and isoelectric points are loaded successfully. By using myoglobin-loaded micelles (myo/m) as a model, the stability of the micelles in physiological conditions and the dissociation and release of functional myoglobin at pH 6.5 are successfully confirmed. Moreover, myo/m shows extended half-life in blood compared to free myoglobin and micelles assembled solely by polyion complex, indicating the potential of this system for in vivo delivery of proteins.
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