Hi Arjun, I suspect that you mean serial dilutions of Ag NPs.
If so, then the Ag NPs will stay in solution longer in viscous liquids like 50% glycerol, which will give you enough time to pipet them as a homogenized solution before they precipitate.
You need to calculate the concentration of your particles first
No in solution, otherwise that concentration is not considering the particles which are not in solution
So the concentration would be in particles per volume
If you dont know the concentration but you are able to wash the particles, by centrifugation and resuspension, you can estimate the concentration given you know the particle size distribution (or an estimate).