Hi Himanshu

A biotemplating peptide might be able to help, I'm not sure of the size of the particles, but you could always contact the corresponding author of the paper, they might even be able to send you a sample of their particles?

There are also many other gold and silver templating peptide sequences that may also be of interest, we recently wrote a highlight article in which there is a list of other such biotemplating sequences that could also offer a useful, green route towards obtaining silver nanoparticles.

http://pubs.rsc.org/en/content/articlelanding/2012/JM/c2jm31620j

I hope this helps

Article Unusual Reactivity of a Silver Mineralizing Peptide

How monodisperse they should be? There are several routes to achieve that without any surface ligand. You can try also, apart from chemical synthesis, laser ablation in solution. As far as I know this gives quite good results.

Thanks for your replies Johanna and Nikodem....I want AgNP size below 10 nm with std dev less than 2 nm. It would be good if a simple route analogous to NaBH4 based reduction of AuCl3 exists for AgNP synthesis as well. I tried and though lot of AgNPs are less than 5 nm but several big ones (15-20 nm) form as well, perhaps due to uncontrolled growth during post nucleation stage because of lesser stability of bare AgNPs compared to AuNPs.

By the way - why do you need such monodisperse AgNPs? The size really does not affect optical properties for an order of magnitude of AgNPs. If you really want to have monodisperse nanoparticles you can try different route than a good synthesis - you can aim for a mediocre synthesisand then apply a filtration method - and there are several, starting from gel electroforesis and finishing on a simple, yet effective, centrifugation in a sucrose gradient. I can try to supply you with some literature regarding this topic.

yes by taking glycine or BSA as caping agent y can prepare nanoparticlrs

Y can used the surfactant or by chemical synthesis with out organic caping agent for synthesizig nanoparticles

Thanks Nikodem and Deepak....gonna try filtration to achieve monodispersity. I am working on core shells and hence monodispersity is important to me.

Use Beta-cyclodextrin. It is nice reduction and capping agent. We could prepare highly mono dispersed, small size and highly stable nano particles.

Picosecond-pulsed laser ablation of a silver target in water or in organic solvent usually provides stable colloidal suspensions of monodisperse silver nanoparticles.