Colloidal Gold FAQs

Frequently Asked Questions (FAQs) for Colloidal gold

Ultra high quality 40nm gold nanoparticles, supplied in a range of concentrations for maximum flexibility.

1. What is the shelf life of Expedeon Colloidal gold?

Our colloidal gold is guaranteed to be stable for up to two years from manufacturing in an unopened bottle stored at 4⁰C. It is recommended to use the colloidal gold within six months from opening.

2. What is the best storage condition?

It is recommended to store the colloidal gold at 4⁰C and use them at room temperature. Freezing must be avoided as it leads to irreversible particle aggregation and the formation of a black precipitate.

3. Is it normal for nanoparticles to settle out of solution?

Yes, this can happen especially with larger size gold nanoparticles (40-80nm). The particles might settle at the bottom of the bottle, leaving a clear solution. This process is reversible: the particles can be resuspended by gently inverting the bottle a few times.

4. In which buffer are the nanoparticles provided?

Our colloidal gold nanoparticles undergo a buffer exchange to remove any residual manufacturing products and are suspended in citrate buffer.

5. How are the gold nanoparticles characterized?

Each batch of colloidal gold, both 10nm and 40nm sizes, is analysed by TEM and UV-Visible spectroscopy to ensure high quality standards. Particles specifications, such as mean size, standard deviation and coefficient of variation, are based on more than 100 single nanoparticle measurements.

6. What if I need more concentrated gold nanoparticles for my applications?

Colloidal gold can be centrifuged, but this might lead to aggregation and impossibility to resuspend the nanoparticles. Our range includes gold nanoparticles concentrated up to 20 OD, but upon request we can also manufacture colloidal gold at a higher OD.

Please get in touch for further information.

7. What is your production scale?

We are able to manufacture colloidal gold in bulk quantities to support any scale of operation, still keeping consistent our quality standards.

Please get in touch with us for further information and to request a quote.

Please see here for ordering & shipping information.