Shape-Dependent Biodistribution of Biocompatible Silk Microcapsules

Sisi Cao, Rui Tang, Gail Sudlow, Zheyu Wang, Keng Ku Liu, Jingyi Luan, Sirimuvva Tadepalli, Anushree Seth, Samuel Achilefu, Srikanth Singamaneni

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Microcapsules are emerging as promising microsize drug carriers due to their remarkable deformability. Shape plays a dominant role in determining their vascular transportation. Herein, we explored the effect of the shape of the microcapsules on the in vivo biodistribution for rational design of microcapsules to achieve optimized targeting efficiency. Silk fibroin, a biocompatible, biodegradable, and abundant material, was utilized as a building block to construct biconcave discoidal and spherical microcapsules with diameter of 1.8 μm and wall thickness of 20 nm. We have compared the cytocompatibility, cellular uptake, and biodistribution of both microcapsules. Both biconcave and spherical microcapsules exhibited excellent cytocompatibility and internalization into cancer cells. During blood circulation in mice, both microcapsules showed retention in liver and kidney and most underwent renal clearance. However, we observed significantly higher accumulation of biconcave silk microcapsules in lung compared with spherical microcapsules, and the accumulation was found to be stable in lung even after 3 days. The higher concentration of biconcave discoidal microcapsules found in lung arises from pulmonary environment, margination dynamics, and enhanced deformation in bloodstream. Red blood cell (RBC)-mimicking silk microcapsules demonstrated here can potentially serve as a promising platform for delivering drugs for lung diseases.

Original languageEnglish (US)
Pages (from-to)5499-5508
Number of pages10
JournalACS Applied Materials and Interfaces
Issue number5
StatePublished - Feb 6 2019
Externally publishedYes


  • biconcave
  • biomimetic
  • layer-by-layer assembly
  • microcapsules
  • red blood cells
  • silk fibroin

ASJC Scopus subject areas

  • Materials Science(all)


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