Hi! what kind of synthesis method are you using? I ussually make them photochemically, so that tie of UV irradiation to the radical precursor would be determinating. One thing that I believe affects every method is the proportion betwwen gold salt , the reductant, and the stabilazing agent. So what ever synthesis you are using, try changing the proportion between them. You can check them through UV until you are sure their are stable and you have no agreggation. then just take a TEM for example to know exactly the size and shape. Hope this help!

Hi,

Usually when you prepare gold nanoparticules, you get spherical ones. But you get prepare cubic, rods, etc. using nucleation process. You can find more information in this review and others.

Hi! what kind of synthesis method are you using? I ussually make them photochemically, so that tie of UV irradiation to the radical precursor would be determinating. One thing that I believe affects every method is the proportion betwwen gold salt , the reductant, and the stabilazing agent. So what ever synthesis you are using, try changing the proportion between them. You can check them through UV until you are sure their are stable and you have no agreggation. then just take a TEM for example to know exactly the size and shape. Hope this help!

As Silvero has mentioned, it's all about the concentration and composition of gold precursor, reducing agent, caping agent, and in addition to that, surfactant. For example, you can make 10-20 nm size Au cluster using albumin as a caping agent (which is also a surfactant by nature). Also incubation time, temperature, controlled addition of the reducing agent, and all this matters. It would be possible to give you better suggestions, if you could briefly mention the synthesis route