Description: The Naval Research Laboratory (NRL) has developed phage-like nanoparticles for the delivery of payloads to targeted eukaryotic cells. The nanoparticles are designed with reactive surface groups that can bind a dye, drug, antibody, etc. The modified nanoparticles can be used for cell tracking, cell imaging, and drug delivery. They are produced from E. coli as tailless T4 bacteriophage and modified to deliver content into targeted eukaryotic cells. In testing conditions, the nanoparticles can retain their shape in the absence of DNA. The tailless bacteriophage is non-contagious, non-toxic, and biodegradable. These features enable it to be used for in vitro diagnostics and potentially for in vivo applications. Dyes delivered by the nanoparticles can aid in intracellular imaging and cell tracking. Because of their size, these nanoparticles have the advantage of being able to deliver a substantial amount of treatment directly to a specified cell, such as a tumor cell. Studies have confirmed that the nanoparticles are non-toxic to human umbilical endothial cells, astrocytes, and liver cells. The nanoparticles have been shown to effectively deliver fluorescent dyes, such as Cy3 and AlexaFluor546. These phage-like nanoparticles have great potential for use in biomedical applications.

Advantages/Features Include:

  • Recovers from E. coli with >90% purity
  • Uses commercially available equipment and techniques for large-scale production
  • Accommodates 1.9 x 104 dyes per nanoparticle, better than TMV or PVX
  • Delivers effective fluorescence in vitro with as few as 350 dyes per particle
  • Accumulates in cells for at least 72 hours

Applications Include:

  • Drug delivery vehicle
  • Cellular imaging in vitro and in vivo
  • Cell tracking in co-cultures
  • Fluorescence-activated cell sorting (FACS)
  • Other flow cytometry applications


  • "Engineered T4 Viral Nanoparticles for Cellular Imaging and Flow Cytometry," Bioconjugate Chemistry, 2001, 22, p. 595-604.

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