I wish to exchange citrate on my 40nm gold particles for a thiol (prochimia.com/products/product/104), however, I always seem to aggregate the gold particles: the initial red colour goes blue, or even darker. Sonication does not get the red colour back; Blue or darker indicates aggregation.
Does anyone know a good method to exchange the citrate for my thiol, without aggregation?
Change of surface will change the zeta potential and thus the stability of the system. Thus, the only routes forward are:
- Change 2 things at once - for example, the thiol additive and pH to bring the thiol surfaced material into a stable region
- Use a steric stabilizer - e.g. PEG or a 50 KDa PEI to stabilize the system during the thiol addition. This will significantly add to the size of your nanoparticles
Some overall guidelines in:
Nov 11th, 2008. Dispersion and nanotechnology http://tinyurl.com/hpywsge
HI
the best option would be to monitor its pH value. there would be a centre point at which it can be stable by the pH. and also if you monitor the zeta potential with each pH value it will give you an idea about the stability.
Best
Shoaib
I assume that your small nanoparticles (curvature!) do not form a stable layer with this reagent. Perhaps a thiol with a very short alkyl chain would be preferable. Another option would be a branched PEG thiol.
Dear Jhon,
Did you activate the S-H group? did you if you sure about it you can change the concentration and pH to reach the optimize condition
Do you really need the positively charged N within your thiol? Try a negatively charged carboxylated thiol.
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