Superparamagnetic nickel colloidal nanocrystal clusters with antibacterial activity and bacteria binding ability

Recent progress in synthetic nanotechnology and the ancient use of metals in food preservation and the antibacterial treatment of wounds have prompted the development of nanometallic materials for antimicrobial applications(1-4). However, the materials designed so far do not simultaneously display antimicrobial activity and the capability of binding and capturing bacteria and spores. Here, we develop a one-step pyrolysis procedure to synthesize monodisperse superparamagnetic nickel colloidal nanocrystal clusters (SNCNCs), which show both antibacterial activity and the ability to bind Grampositive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, as well as bacterial spores. The SNCNCs are formed from a rapid burst of nickel nanoparticles, which self-assemble slowly into clusters. The clusters can magnetically extract 99.99% of bacteria and spores and provide a promising approach for the removal of microbes, including hard-totreat microorganisms. We believe that our work illustrates the exciting opportunities that nanotechnology offers for alternative antimicrobial strategies and other applications in microbiology.