Vancomycin-modified nanoparticles for efficient targeting and preconcentration of Gram-positive and Gram-negative bacteria.

A series of vancomycin-modified nanoparticles were developed and employed in magnetic confinement assays to isolate a variety of Gram-positive and Gram-negative bacteria from aqueous solution. We determined that the orientation/architecture of vancomycin on the surface of the nanoparticles and the overall surface coverage is critical in mediating fast and effective interactions between the nanoparticle and the pathogen cell wall surface and only one orientation/architecture in a series of modified nanoparticles leads to the efficient and reproducible capture of several important pathogenic bacteria. Interestingly, as the nanoparticles increase in diameter (from approximately 50 to 2800 nm), it is necessary to incorporate a long linker between the nanoparticle surface and the vancomycin moiety in order for the surface bound probe to efficiently confine Gram-positive bacteria. Finally, we also determined that the time required for efficient labeling and subsequent magnetic confinement significantly decreases as the size of the nanoparticle and the vancomycin surface coverage on the nanoparticle increases. As disease detection technologies transition to "lab-on-a-chip" based platforms it is necessary to develop strategies to effectively and inexpensively preconcentrate cells from large volume to volumes more amenable to these types of microfluidic devices. These small molecule-modified superparamagnetic nanoparticles can provide a means by which this can be accomplished.