Improved Doxorubicin Encapsulation and Pharmacokinetics of Ferritin-Fusion Protein Nanocarriers Bearing Proline, Serine, and Alanine Elements

Biomacromolecules. 2016 Feb 8;17(2):514-22. doi: 10.1021/acs.biomac.5b01446. Epub 2015 Dec 30.


A novel human ferritin-based nanocarrier, composed of 24 modified monomers able to auto-assemble into a modified protein cage, was produced and used as selective carrier of anti-tumor payloads. Each modified monomer derives from the genetic fusion of two distinct modules, namely the heavy chain of human ferritin (HFt) and a stabilizing/protective PAS polypeptide sequence rich in proline (P), serine (S), and alanine (A) residues. Two genetically fused protein constructs containing PAS polymers with 40- and 75-residue lengths, respectively, were compared. They were produced and purified as recombinant proteins in Escherichia coli at high yields. Both preparations were highly soluble and stable in vitro as well as in mouse plasma. Size-exclusion chromatography, dynamic light scattering, and transmission electron microscopy results indicated that PASylated ferritins are fully assembled and highly monodispersed. In addition, yields and stability of encapsulated doxorubicin were significantly better for both HFt-PAS proteins than for wild-type HFt. Importantly, PAS sequences considerably prolonged the half-life of HFt in the mouse bloodstream. Finally, our doxorubicin-loaded nanocages preserved the pharmacological activity of the drug. Taken together, these results indicate that both of the developed HFt-PAS fusion proteins are promising nanocarriers for future applications in cancer therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alanine / chemistry
  • Animals
  • Antibiotics, Antineoplastic / chemistry*
  • Antibiotics, Antineoplastic / pharmacokinetics
  • Antibiotics, Antineoplastic / pharmacology
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Doxorubicin / chemistry*
  • Doxorubicin / pharmacokinetics
  • Doxorubicin / pharmacology
  • Drug Screening Assays, Antitumor
  • Drug Stability
  • Ferritins / chemistry
  • Half-Life
  • Humans
  • Mice, Inbred BALB C
  • Nanocapsules / chemistry*
  • Peptides / chemistry
  • Polyethylene Glycols / chemistry
  • Proline / chemistry
  • Recombinant Fusion Proteins / chemistry
  • Serine / chemistry


  • Antibiotics, Antineoplastic
  • Nanocapsules
  • Peptides
  • Recombinant Fusion Proteins
  • Polyethylene Glycols
  • Serine
  • Doxorubicin
  • Ferritins
  • Proline
  • Alanine