General Strategy for Direct Cytosolic Protein Delivery via Protein-Nanoparticle Co-engineering

ACS Nano. 2017 Jun 27;11(6):6416-6421. doi: 10.1021/acsnano.7b02884. Epub 2017 Jun 15.


Endosomal entrapment is a key hurdle for most intracellular protein-based therapeutic strategies. We report a general strategy for efficient delivery of proteins to the cytosol through co-engineering of proteins and nanoparticle vehicles. The proteins feature an oligo(glutamate) sequence (E-tag) that binds arginine-functionalized gold nanoparticles, generating hierarchical spherical nanoassemblies. These assemblies fuse with cell membranes, releasing the E-tagged protein directly into the cytosol. Five different proteins with diverse charges, sizes, and functions were effectively delivered into cells, demonstrating the generality of our method. Significantly, the engineered proteins retained activity after cytosolic delivery, as demonstrated through the delivery of active Cre recombinase, and granzyme A to kill cancer cells.

Keywords: cytosolic protein delivery; hierarchical nanoassembly; membrane fusion; nanoparticles; protein engineering.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cell Line
  • Cell Membrane / metabolism
  • Cytosol / metabolism*
  • Gold / chemistry
  • Humans
  • Membrane Fusion
  • Metal Nanoparticles / chemistry*
  • Mice
  • Nanoconjugates / chemistry*
  • Particle Size
  • Protein Engineering / methods*
  • Proteins / chemistry*
  • Proteins / metabolism


  • Nanoconjugates
  • Proteins
  • Gold