(334e) Magnifying Differences in the Cross Over Frequency of Bacteria Using Solvent Modification and Antibody Tagged Nanoparticles

ielectrophoresis (DEP) can potentially serve as a means to rapidly isolate pathogenic bacterial species and strains of interest from a mixture containing other related, often non-pathogenic, species. Two species can be separated from each other easily using DEP if they have different Cross-Over Frequencies (COFs). The COF depends of a bacterial cell in a given solution depends on the properties (conductivity and dielectric constant) of the cell membrane and the cell interior, and on those of the solution in which it is suspended, and thus each species should have a different characteristic cross-over frequency.

In practice, however, it is seen that these crossover frequencies of bacteria can be very close together, thus making their separation using DEP quite difficult and inefficient. We propose a practical solution to this problem by formulating a ?DEP buffer? consisting of Mannitol, Amino Hexanoic Acid, and Sodium Chloride in which the differences in COF are magnified. The buffer is hypertonic, has a low conductivity but high dielectric constant, and by magnifying the contribution of the properties of the cell membrane in determining the COF, enables resolution of many different bacterial species like E.coli, Lactobacillus, Pseudomonas, and Salmonella.

Closely related strains (such as E coli O157 and E coli K-12) however, are still not resolvable. We present a way of doing so using antibody-tagged nano-particles to bind to particular strains. Once these particles bind to the bacteria, the COF of the nano-particle bacteria conjugate differs from that of the bacteria alone.

These practical techniques open the door to detecting the presence of target pathogenic bacteria from mixtures containing large numbers of other bacteria