(209c) Microscopic Analysis Of Adsorption Of E. Coli And Staphylococcus Aureus On Single-Wall Carbon Nanotube Aggregates

Adsorption of a Gram-positive bacterium, Staphylococcus aureus (S. aureus) and Gram-negative bacterium, Escherichia coli (E. coli) on carbon nanotube aggregates was investigated in shaker experiments and microscopic analyses for biosensor applications. Carbon nanotube-based biosensors have the potential of rapid concentration and detection of pathogens in drinking water systems. The signal strength of the biosensors is directly proportional to the immobilized analyte concentration on the carbon nanotube probes and is highly dependent on how well the microorganisms are associated with the nanotubes. Both adsorption kinetics and equilibrium of the bacterial species on carbon nanotubes were determined in the shaker experiments. Microscopic analyses including SEM, TEM with and without ultramicrotomy, and confocal microscopy were performed to visualize the association of the bacteria with carbon nanotubes. It was found from the adsorption measurements that S. aureus have 12-100 times stronger and closer association with the single-wall nanotube aggregates than the E. coli. The small size S. aureus diffuse 25 times faster than E. coli in the carbon nanotube aggregates. Microscopic analyses have qualitatively confirmed the adsorption results. The preliminary results from this work suggest that single-wall carbon nanotubes are good candidate for biosensors.