PEG-poly(amino acid) block copolymer micelles for tunable drug release

Andrei Ponta, Younsoo Bae

Research output: Contribution to journalArticlepeer-review

73 Scopus citations


Purpose: To achieve tunable pH-dependent drug release in tumor tissues. Methods: Poly(ethylene glycol)-poly(aspartic acid) [PEG-p(Asp)] containing 12 kDa PEG and pAsp (5, 15, and 35 repeating units) were prepared. Hydrazide linkers with spacers [glycine (Gly) and 4-aminobenzoate (Abz)] were introduced to PEG-p(Asp), followed by drug conjugation [doxorubicin (DOX)]. The block copolymer-drug conjugates were either reconstituted or dialyzed in aqueous solutions to prepare micelles. Drug release patterns were observed under sink conditions at pH 5.0 and 7.4, 37°C, for 48 h. Results: A collection of six block copolymers with different chain lengths and spacers was synthesized. Drug binding yields were 13-43.6%. The polymer-drug conjugates formed <50 nm polymer micelles irrespective of polymer compositions. Gly-introduced polymer micelles showed marginal change in particle size (40±10 nm), while the size of Abz-micelles increased gradually from 10 to 40 nm as the polymer chain lengths increased. Drug release patterns of both Gly and Abz micelles were pH-dependent and tunable. The spacers appear to play a crucial role in controlling drug release and stability of polymer micelles in combination with block copolymer chain lengths. Conclusion: A drug delivery platform for tunable drug release was successfully developed with polymer micelles possessing spacer-modified hydrazone drug-binding linkers.

Original languageEnglish
Pages (from-to)2330-2342
Number of pages13
JournalPharmaceutical Research
Issue number11
StatePublished - Nov 2010

Bibliographical note

Funding Information:
Authors acknowledge financial support provided by the Kentucky Lung Cancer Research Program.


  • controlled drug delivery
  • functional block copolymers
  • pH-sensitive drug release
  • polymer micelles
  • tunable drug release

ASJC Scopus subject areas

  • Biotechnology
  • Molecular Medicine
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry
  • Pharmacology (medical)


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