P145: Ultrasonic disintegration of microbes in a microscale device for biochemical analysis

The micro-scale analysis of intracellular contents such as proteins or nucleic acids is gaining significance in biology. Other than enabling minimized analytical and cell biology profiling of processes at the cellular level, microfluidic technology is also finding newer applications relating to micro-culturing of cells for high throughput screening of bioactive components and bioprocess research. Escherichia coli and yeast species like Pichia pastoris or Saccharomyces cerevisiae are widely-used for genome-scale library screening and functional protein expression. However, before micro-scale analysis can be routinely realized, an effective lysis process for the release of active intracellular contents is vital.

In microfluidics, cell lysis can be accomplished by means of chemical, thermal, electrical or mechanical lysis. Of these, chemical lysis, electrical cell lysis and thermal lysis with heat frequently lead to the denaturation of proteins or interfere with subsequent assays. At the macro-scale in bulk fluids, sonication is a mechanical process that generates millions of high-energy microbubbles and is normally performed at the lab-scale to attain lysis of cells. The ability to introduce collapsing high-energy cavitation bubbles in a microfluidic setting offers an unparalleled potential for disruption of the cellular membrane, hence facilitating downstream analysis. The present experimental approach has successfully generated intense inertial oscillating cavitation in an in-house microfluidic system. The cavitation is initiated using simple piezoelectric transducers coupled into the microfluidic devices through a glass substrate. We demonstrated shear generated from the oscillating bubbles is sufficient to deform and disrupt microbial cells including Escherichia coli, Pichia pastoris and Bacillus subtilis.