Electrokinetic separation of bacteriophage ϕKZ from bacterial cells

The rise of drug-resistant bacteria and nosocomial infections has intensified the need for alternative antimicrobial strategies such as phage therapy. However, clinical adoption remains hindered by the lack of easily adoptable, high-yield purification methods. This study presents the first report of the electrophoretic separation of bacteriophage ϕKZ from binary mixtures with microparticles and Escherichia coli cells. Insulator-based electrokinetic (iEK) microchannels were employed to exploit the differences in electrophoretic migration and the nonspecific binding affinity of bacteriophages to the surfaces of both microparticles and bacterial cells. The electrophoretic mobilities of all analytes were characterized in isolation in a uniform rectangular microchannel. Additionally, the microparticles and E. coli cells were also characterized in the presence of ϕKZ to assess the effect of nonspecific binding, which resulted in the reduction in zeta potential of up to approximately 8 mV. Subsequently, employing the mobility data, COMSOL Multiphysics was utilized to identify the appropriate separation voltages to be used in the iEK channels. Separations under the streaming electrokinetic regime were carried out at the field strengths of 194.3 V cm^-1 and 430.4 V cm^-1. Furthermore, an additional trapping-streaming separation experiment between E. coli cells and ϕKZ was achieved at 580.6 V cm^-1. These findings demonstrate the feasibility of a novel electrokinetic-based purification strategy for the rapid and scalable isolation of bacteriophages.