In this study, amino functionalized poly glycidyl methacrylate (am-PGMA) based microspheres prepared via soap-free emulsion polymerization were served as polymeric matrices for silver nanoparticles (Ag NPs) loading and applied as anti-bacterial agent. The amino and hydroxyl enriched am-PGMA based microspheres served as both matrix for Ag+ absorbance through coordination bond and reduce agent under hydrothermal condition in a high-pressure steam sterilization. The effects of chemical structure of microspheres on the morphology of Ag NPs/polymer composites were investigated. Am-PGMA/Ag composite spheres with ultra-fine Ag NPs up to 26 wt% were well characterized and their antibacterial activity were studied and discussed in detail. It was found that the Ag NPs loading in microspheres showed comparable anti-bacteria activities in terms of Ag with the minimum inhibitory concentration (MIC) low to 20 and 20 mg/L (equal to 5.2, 52 mg/L Ag) for Escherichia coli and Staphylococcus aureus respectively. The obtained composites spheres (am-PGMA/Ag) are promising alternative anti-bacterial agents in industrial and biomedical applications. (C) 2016 Elsevier B.V. All rights reserved.