Attachment of superparamagnetic particles to the surface of bacteria. Panel A shows the two principles for covalent linkage of magnetic particles to bacteria. Top: glutaraldehyde can be used to create a pentyl bridge between amino group-exposing particles and the bacteria. Bottom: carbodiimide activation of carboxy group-exposing particles can be used to create peptide bonds with the bacteria. Panel B demonstrates the visualization of magnetite particles (arrowheads). Upper images: phase contrast and differential interference contrast, respectively; scale bar 1 μm. Lower image: electron micrograph depicting a bacterium (S. pyogenes) with attached magnetite particles; scale bar 0.5 μm. Panel C illustrates that, using the carbodiimide protocol, the attachment of particles (arrowhead) does not compromise the viability of bacteria, as determined by a BacLight Live-Dead kit (green = live, red = dead); scale bar 1 μm.
Lönnbro et al. BMC Cell Biology 2008 9:35 doi:10.1186/1471-2121-9-35