For most applications our gold nanoparticles can be used without any additional washing steps. If you have a sensitive application that requires additional washing the best way to do so is by either centrifugation or filtration. For recommended centrifugation speeds and times please refer to Storage & Handling of gold nanoparticles

The size and the surface chemistry of gold nanoparticle to use is very dependent upon the intended application. Please see our Gold Nanoparticle Product Selection Guide to find the most optimal product for your particular application.

Settling of gold nanoparticles on the bottom of the storage flask is completely normal and is especially common for larger sized particles, which settle at a greater speed. Settling does not affect the performance of the particles. Prior to use, simply swirl the solution to properly disperse your gold nanoparticles and generate a homogenous solution.

Our standard gold nanoparticles are stable for at least 1 year if stored unopened and as specified at 4-25 degrees Celsius. Do NOT store our non-functionalized standard gold nanoparticles in the freezer since this cause irreversible aggregation, see our gold nanoparticles handling and storage tech note.

Due to repulsive forces arising from the surface charge of gold nanoparticles, an energy barrier must be overcome for individual particles to interact. When no (or small) amounts of electrolytes such as NaCl are present, this energy barrier is too strong for interaction to occur between particles. However, upon addition of NaCl this energy barrier is reduced allowing the gold nanoparticles to interact and aggregate. This aggregation causes a phenomenon called surface-plasmon coupling which changes the adsorption maximum of light to a higher wavelength resulting in a change in colour of the solution.

Freezing of our non-functionalized gold nanoparticles causes irreversible aggregation and can be observed by a clear change in colour of the solution, see our gold nanoparticles handling and storage tech note for more information and examples.

A gold conjugate can be tested for the presence of the conjugated antibody (or antigen) using immunoblotting (dot-blot) or alternatively using our ready-to-use Conjugation QC Lateral Flow Dipstick Kit. Another alternative is to directly use the gold conjugate in the downstream application and compare performance to a negative control gold conjugate.

The number of nanocrystals per mg is approximately 1.2x10E+15.

All of our quantum dots have the same size with a molecular weight of 650,000 Da.

The quantum efficiency of our quantum dots is 55-65% (alkyl functional fluorescent nanocrystals compared to laser dyes). Our water soluble quantum dots have 15% lower quantum efficiency compared to the alkylated fluorescent nanocrystals.