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A miniaturized microfluidic device was developed to facilitate electromanipulation of bacterial respiratory pathogens. The device comprises a microchip with circular aluminum electrodes patterned on glass, which is housed in a microfluidic system fabricated utilizing polydimethylsiloxane. The device provides sample preparation capability by exploiting positive dielectrophoresis (DEP) in conjunction with pulsed voltage for manipulation and disruption of Bordetella pertussis bacterial cells. Positive DEP capture of B. pertussis was successfully demonstrated utilizing 10 Vrms and 1 MHz ac fields. Application of dc pulses (300 V amplitude and 50 mu s pulsewidth applied 1 s apart) across the aluminum electrodes resulted in electrodisruption and lysis of B. pertussis bacterial cells. Real-time polymerase chain reaction, a 23 factorial experimental design and transmission electron microscopy were used to evaluate bacterial cell manipulation and factors affecting bacterial cell disruption. The main factors affecting bacterial cell disruption were electric field strength, the electrical conductivity of the cell suspension sample, and the combined effect of number of pulses and sample conductivity. The bacterial deoxyribonucleic acid target remained undamaged as a result of DEP and cell lysis experimentation. Our findings suggest that a simple miniaturized microfluidic device can achieve important steps in sample preparation on-chip involving respiratory bacterial pathogens.
Date of Publication: Oct. 2008