A Kiani- Karanji - De partment of Chemistry, Sharif University o f Technology, Tehran, Iran
M Padervand - De partment of Chemistry, Sharif University o f Technology, Tehran, Iran
H Salari - De partment of Chemistry, Sharif University o f Technology, Tehran, Iran
S Haghighi - Pasteur In stitute, Tehra n, Iran
M.R Gholami - De partment of Chemistry, Sharif University o f Technology, Tehran, Iran

Magnetic nanoparti cles are widely used in recent researches. They have many potential applicati ons in Biolo gy, Catalyst, and some other fields of researc h in science. Drug delivery,Antibact erial activity and imaging with magnetic reso nance (MRI)are some e xamples of their applicati ons that are reported in the articles and literatures [۱], due to their high satu ration magneitzation, low toxicity, and biocom patibility.For Biologi cal usage,because of their Biologic al fitness an d chemical stability, nanostructures of Fe۳O۴are the first cho ices. Although there ha e been many important developments in the synthesis of ma gnetic nanoparticles, the s tability of these particles for a long time without a gglomeratio n or precipitation is still remain an im portant subject [۲].The refore, it is necessary to develop efficient methods to improve the chemical stability of magnetic nanoparticles. All the pro tection strategies result in magnetic nanoparticles with a co re–shell stru cture, its m eaning, the naked ma gnetic nanoparticle as a core is coated by a shell, isolating the core again st the mater ials that sur round around it.Silica Co atingis one of the most strategies that are used for this purpose. A silica shell doe s not only protect the ma gnetic cores, but can prevent the d irect contac t of the ma gnetic core with additional agentlink to the silica surface too,thus avoidin g unwanted interactions [۳].Silica layers have several advanta ges becaus e of their stability unde r aqueous c onditions ( at least if th e pH value is sufficiently low), easy s urface modif ication, and easy control of interparticle interactions, both in s olution and within structures, through variation of the shell thickness.The biol ogical activ ities of silv er make it a suitable ca ndidate for applications in industr y and hospitals as a microorganism in activator. S ilver is als o known for its water and air purifying ability [۴ ]. In spite of these fi ndings, research is goi ng on to de velop still more conve nient methods to exploit the beneficia l properties of silver in newer applications. In this contex t, we studied the interactio n of metallic nanoparticles with M icroorganisms like bacteria. In addition, the antibacterial acti vity of Sil ver compare d with Gold and Cup per accordi ng to role o f the polymers which embedded the metallic particles into polymer branc hes.

Magnetic nanoparticles, PEG, PPG, Antibacterial activit y, Escherichia coli, Staphylococcus aure us