The antibacterial behavior of bovine serum albumin conjugated zinc oxide nanoparticles against Escherichia coli was investigated. The zinc oxide nanoparticles were synthesized by using bovine serum albumin as the structure directing agent. And the morphology and crystal phase of the zinc oxide nanoparticles were determined by transmission electron microscopy, X-ray diffractograms and Fourier transform infrared spectrograph techniques. The synthesized zinc oxide nanoparticles showed high antibacterial activity when compared with plain zinc oxide. And the antibacterial activity was assessed by measuring the growth inhibition and testing the zone of inhibition. Furthermore, the plausible mechanism of antibacterial behavior was attributed to the generation of reactive oxygen species by zinc oxide nanoparticles. (C) 2014 Elsevier B.V. All rights reserved.