Alas, the Turkevich’ protocol (citrate only) has not yet been fully adapted to produce Au nanoparticles below 10 nm due to kinetic limitations. For acceleration the process of nucleation, it’s necessary to use more strong reductant. In fact, the most common reducing agent is sodium borohydride in the presence of capping ligands (citrate, for example). Rakesh Kumar Tekade proposes to vary the concentration of citrate as stabilizer of your system. Or see a good sample of using tannins as co-reductant and stabilizer of citrate's way.

Article Size-controlled Synthesis of sub-10 nm Citrate-stabilized Go...

Socium citrate reduction gives uni disperse AuNPs of size. You need to optimize the amount of sodium citrate.

Hi Rakesh, I have tried sodium citrate to synthesize AuNP. However I was unable to achieve less than 8nm particles. What molar ratio would you suggest me to maintain to get around 5 nm particle?

Alas, the Turkevich’ protocol (citrate only) has not yet been fully adapted to produce Au nanoparticles below 10 nm due to kinetic limitations. For acceleration the process of nucleation, it’s necessary to use more strong reductant. In fact, the most common reducing agent is sodium borohydride in the presence of capping ligands (citrate, for example). Rakesh Kumar Tekade proposes to vary the concentration of citrate as stabilizer of your system. Or see a good sample of using tannins as co-reductant and stabilizer of citrate's way.

Article Size-controlled Synthesis of sub-10 nm Citrate-stabilized Go...

Hi.. Shcherbakov , I synthesized gold nanoparticles by the above method. But, its difficult to precipitate. I used water, acetone, ethanol and their combination to precipitate but I can't succeeded. Can you please suggest me any solvent to precipitate those particles?

Prakash Parajuli,

What for? Purification or analysis? Really, the sols stabilized by both electrostatic and steric repulsion are too stable and hardly precipitated without surface modification. For the analytical purposes you can try the protocol proposed by authors for the same sol: “For sample preparation, 5mL of colloidal gold solution was precipitated by the addition of 5 mL of ethanol and 3 μL of dodecanethiol followed by centrifugation at 3000g for 30 min.”

Best regards

Article Room-temperature synthesis of gold nanoparticles - Size-cont...

Thanks Shcherbakov for your help.

Hai Dr. Shcherbakov,

I am doing the synthesis of gold nanoparticles(5 nm) using sodium citrate as reducing agent. Shall I use the same procedure as you mentioned above? I have one more question also. May I use 1-octadecanethiol instead of dodecanethiol?

Thanks in advance.

Hi Saha,

Using the only citrate, we can not achieve less than 10 nm size of nanoparticles. you can add some reducing agent as well as a stabilizing agent. for example, you can get gold nanoparticle with

Hi Mangaiyarkarasi,

You can use the 1-octadecanethiol instead of dodecanethiol. 

The fluorescence will originate for this method. But the fluorescence arises due to ligand to metal charge transfer and gold nanoclusters (not nanoparticles).

Thank you Gopi,

   If we use 1-octadecanethiol, is there any structural changes happened in XRD spectra of gold nanoparticles. 

Dear Mangaiyarkarasi, Yes, the crystalline nature of gold nanoparticles depends on the stabilising agent. you will get different crystal and planes in gold nanoparticles by different alkanethiol.