You can use a soluble silver salt and mix with poliuerea polymer in aqueous solution. You can expose it to uv radiation and dry it...

Yess, using soluble silver salt like AgNo3 along with poly-urea

start from w/w ratio ranging from 1:1 to 1:5 ( AgNo3 : poly-urea and freeze dry the mixture for long storage.

if you want to prepare nanoparticles try Ascorbic acid ( same weight as AgNo3) as reducing agent to generate yellow coloured silver nano particles.

No need to add capping agent i feel poly-urea will itself act as capping agent give it a try!!

Thank you so much ...my question is do I need a surfactant or poly urea functional groups are enough to stabilize the nps...thanks 

I feel poly urea is sufficient for stabilization.