Surface Displaceable Salt
Stable in
Stable in
Stable in
Polar Organics
Stable in
Non-Polar Organics
Conjugatable Charge
at pH 7
Citrate Learn more +
  • Most commonly requested capping agent
  • Easily displaceable with other molecules for binding studies or custom functionalization
  • High degree of electrostatic stabilization
PVP (Polyvinylpyrrolidone) Learn more +
  • Associates very strongly to metal surfaces, giving excellent colloidal stability over a wide range of conditions
  • Nanoparticles can be dispersed in a wide variety of protic and aprotic polar solvents
  • Stable in high ionic strength solutions and at high concentrations
Lipoic Acid Learn more +
  • Dithiol forms a strong, stable bond with metal surfaces and the acid provides a highly negatively charged surface
  • The free carboxylic acid can be used for conjugation or labeling; contact us to discuss your application
BPEI (Branched Polyethyleneimine) Learn more +
  • Highly aminated, positively charged organic surface coating
  • Large number of free amines for conjugation to targeting molecules
PEG (Polyethylene Glycol) Learn more +
  • Provides excellent dispersibility in water and protic solvents and increases compatibility in biological systems
  • Covalently bound to the nanoparticle surface to prevent desorption over time and increase colloidal stability
  • Custom variants available with PEG of different molecular weights and free functional groups for labeling or conjugation
Silica Learn more +
  • Increased particle stability in a wide range of solvents
  • Versatile conjugation surface for attaching functional groups or creating hydrophobic or fluorophillic surfaces
  • Nanoporous structure allows low molecular weight molecules to be loaded into the shell
Amine-Functionalized Silica Learn more +
  • Positively charged silica colloids and silica-coated nanoparticles
  • Useful for binding studies, conjugation with carboxyl-containing molecules through EDAC coupling, or binding to dyes and molecules with isothiocyanate (ITC) or amine-reactive esters
Other Functionalized Silica Learn more + Varies Varies Varies Varies Varies Varies
  • Many custom coatings are available to provide specific functionality at the particle surface or create particles compatible with different solvents or composites
  • Contact us to discuss your application and custom surface functionalization needs
Carbonate Learn more +
  • Most easily displaced surface
  • Ideal pH (8–9) and low salt buffer for physisorption of antibodies
Carboxyl Learn more +
  • COOH groups provide functionality for covalent coupling
  • Stable from pH 4-10 and up to 2× PBS buffer
NHS Learn more +
  • Dried redispersible powder
  • Amine reactive surface
  • Easiest way to covalently bind an amine containing molecule such as an antibody to the surface of the gold particle
Dodecanethiol Learn more + N/A
  • Hydrophobic coating renders particles soluble in organic solvents and compatible with non-polar polymer composite materials
  • Can be dispersed in low surface-energy solvents for coating applications requiring uniform particle deposition