We have successfully synthesized polyacrylonitrile (PAN) nanofibers impregnated with Ag nanoparticles by electrospinning method at room temperature. Briefly, the PAN-Ag composite nanofibers were prepared by electrospinning PAN (10% w/v) in dimethyl formamide (DMF) solvent containing silver nitrate (AgNO3) in the amounts of 8% by weight of PAN. The silver ions were reduced into silver particles in three different methods i.e., by refluxing the solution before electrospinning, treating with sodium borohydride (NaBH4), as reducing agent, and heating the prepared composite nanofibers at 160 degrees C. The prepared PAN nanofibers functionalized with Ag nanoparticles were characterized by field emission scanning electron microscopy (FESEM), SEM elemental detection X-ray analysis (SEM-EDAX), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV-VIS) analytical techniques. UV-VIS spectra analysis showed distinct absorption band at 410 nm, suggesting the formation of Ag nanoparticles. TEM micrographs confirmed homogeneous dispersion of Ag nanoparticles on the surface of PAN nanofibers, and particle diameter was found to be 515 nm. It was found that all the three electrospun PAN-Ag composite nanofibers showed strong antibacterial activity toward both gram positive and gram negative bacteria. However, the antibacterial activity of PAN-Ag composite nanofibers membrane prepared by refluxed method was most prominent against S. aureus bacteria. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012