Sonication has already been widely used in tearing open cells in molecular, collular, cellular, microbiology and other laboratories. The chemical composition of the cells or their buffer remains unchanged during the sonification process, and the cells’ charge does not alter as it does in electroporation process. Sonication is quite a simple method, and only a few tips should be followed according to the experiment and cell types.
For the beginning, prepare a cell dispersion in suitable buffer or media, place the dispersion in a beaker of ice or ice water for further cooling. Rinse the nozzle of the sonication device with water, then dry it with a Kimwipe. Switch on the sonication or Cell Disruptor machine, set the Output Power to an appropriate value according to the cell type and experiment condition. Dip the nozzle of the sonicator in the cell sample tube, turn on the sonicator to conduct sonication for 5 to 30 seconds. Notice that, longer sonication than 30 seconds may cause the sample overheated or even damaged. In order to ensure different areas of the volume all be well sonicated, you can slowly move the sample tube around the nozzle during the sonication process. Besides, you should also ensure that the nozzle tip does not reach near the volume surface, in case leading to sample bubbling or foaming. After the completion of the first sonication, invert the sample to mix it, sonicate the sample again for another equal time with the sample being cooled on ice.
Optimization Is Important
For different cell line, there usually exists different optimized sonication protocol. You should identify the ideal balance between well sheared cells and the damaged or denatured ones. The optimized protocol can be obtained by adjusting the amount of sonication time and Output Power settings, and then checking the cells using a microscope for fractionation. For example, you can carry three 5-second sonication with the Output Power settings of 50 percent first. If only a small part of the cell population were damaged or denatured, you can accordingly increase the sonication time and the output power.
Take E. Coli cells for example. E. Coli cells are intensively used for growth and purification of a surface-receptor-binding protein (C-terminal fragment of Clostridium perfringens enterotoxin, or “C-CPE”). The optimized protocol for sonicaton is: cell volume– 7 to 10mL; amount of time–two 30-second bursts; output power: maximum Output Power. The cell dispersion buffer compromises 1x PBS and 0.2mg/mL lysozyme.
Besides, the sonication machine for the sonication of E. Coli cells is Ultrasonic Cell Disruptor.