Description: The Naval Research Laboratory (NRL) has developed a chemical means of providing custom functionalization of both semiconductor core/shell quantum dots (QDs) and gold nanoparticles. A series of modular ligands have been synthesized that provide multiple functionalities to the nanoparticles, as desired, including water solubility, tight anchoring to the nanoparticle surface and access to a variety of different terminal functional groups for subsequent (bio)modification and covalent attachment. Amongst the unique characteristics afforded by the ligands are the abilities to remain stable, aggregate free and/or luminescent in a wide pH range and high salt concentrations over extended periods of time. This improves the shelf life and utility of custom nanoparticles and conjugates based upon this chemistry for biosensing and bioimaging applications.

Advantages/Features Include:

  • Water solubility and lack of aggregation
  • Very stable over broad acidic to basic range (pH 4-11) and for long time-periods (months)
  • Access to multiple bioconjugation chemistries (EDC, metal-affinity)
  • Particle sizes with small hydrodynamic radii
  • Incorporates a polyethylene glycol group for optimal biocompatibility

Applications Include:

  • Research reagents
  • Biosensing and bioimaging
  • Drug discovery
  • Cell delivery
  • Nanotechnology


  • "Poly(ethylene glycol)-Based Bidentate Ligands to Enhance Quantum Dot and Gold Nanoparticle Stability in Biological Media," Nature Protocols 4 (2009) 412-423.
  • "Modular Poly(ethylene-glycol) Ligands for Biocompatible Semiconductor and Gold Nanocrystals with Extended pH and Ionic Stability," Journal of Materials Chemistry 18 (2008) 4949-4958.
  • "Enhancing the Stability and Biological Functionalities of Quantum Dots via Compact Multifunctional Ligands," Journal of the American Chemical Society 129 (2007)13987-13996.

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