Investigating the effect of reagent parameters on the efficiency of cell lysis within droplets

Cell lysis is an essential primary step in cell assays. In the process of cell lysis, the cell membrane is destroyed and the substances inside the cell are extracted. By utilizing a droplet-based microfluidic platform for cell lysis, the mixer unit that is required for mixing lysis reagents with the cells can be excluded, and thus, the complexity of the fabrication process is reduced. In addition, lysing the cells within the droplets will prevent the cells from exposure to the channel walls, and as a result, cleanliness of the samples and the device is maintained. In this study, cell lysis within the droplets and the parameters affecting the efficiency of this process are investigated using a computational fluid dynamics model. Both the cell solution and the lysis reagents are encapsulated within a droplet and the lysis procedure is simulated inside the droplet. It is known that the secondary flows generated inside the droplet facilitate the mixing process. In this study, we used this effect to improve the efficiency of cell lysis in droplet and the improvement is shown to be attributed to activating an advection mechanism besides the diffusion mechanism inside the droplet. It is also shown that increasing the concentration of the lysis reagents does not have a significant effect on the efficiency of the cell lysis. The effect of the volume fraction of the lysis reagents is also studied, which is shown to be an effective factor in controlling the efficiency of the cell lysis. The lysis procedure is simulated with lysis reagent volume fractions of 50%, 66%, 80%, 90%, and 97%. The lysis efficiency is found to be 38.45%, 45.3%, 57.6%, 82.4%, and 100%, respectively, while the droplet travels through a 2 mm-long microchannel within 0.25 s. This study shows that the droplet microfluidic platform is a powerful tool for performing fast and reliable cell lysis.