Self-assembly of Au nanoparticles with Fe ions is used to develop magnetic nano-nets similar to fishing nets for capture and removal of microbes in aqueous medium. The nano-nets have a high aspect ratio, span microns in length with openings of 80-300 nm. This allows them to sample the liquid medium even at low volume fraction and also entrap the microbes in the solution. The nets and the trapped microbes can be effectively pulled from the solution by using an off the shelf magnet. Since the capture is based on physical contact, the nano-nets overcome the ability of the microbes to develop resistance to the cytotoxic effects of chemical compounds and nanomaterials. Using the nano-nets an absolute inactivation of 0.9 is achieved in 5 min. in a non-deaerated solution with Escherichia coli (E. coli). Further the removal of the nano-nets along with the captured microbes also predominantly eliminates the nanomaterial from the aqueous medium for future use. (C) 2018 Elsevier Inc. All rights reserved.