Figure 1.

Scheme for chimeric phage detection of bacterial species. (a) M13 phage (gray) is engineered to express a foreign receptor-binding protein (blue circle) fused to the minor coat protein pIII, and the chimeric phage is thiolated (yellow) through EDC chemistry. (b) Thiolated chimeric phages are added to media containing bacteria (blue rectangle) and may attach to the cells. Centrifugation separates cell-phage complexes from free phage. The pellet is resuspended in solution with gold nanoparticles (red), whose aggregation on the thiolated phage produces a color change (purple).