Materials that selectively bind bacteria can be useful tools for detecting pathogens. But developing such materials inexpensively for a range of targets can be a challenge. Cameron Alexander, Klaus Winzer, and Giuseppe Mantovani of the University of Nottingham, in England, and coworkers simplified the process by letting bacteria do the work of templating and synthesizing their own cell-binding polymers (Nat. Mater. 2014, DOI: 10.1038/nmat3949). The researchers mix bacteria with a soup of monomers, which bind to cells in patterns determined by native molecules already on the cell surface. The bacteria naturally produce catalytically active copper that then promotes polymerization of the bound monomers. The templated polymers, which differ from polymers formed in bulk solution, are removed from the bacteria by centrifugation. When the templated polymers are introduced to a bacteria-laden sample, they preferentially bind the types of bacteria used to template them and induce formation of large cell clusters. Such aggregation doesn’t occur with the nontemplating bacteria. The researchers further harnessed the bacteria’s copper metabolism to catalyze attachment of fluorescent markers to templated polymers on cell surfaces. The fluorescent labels could thus be used to quickly detect pathogens in diagnostic tests, the researchers suggest.