Preventing Excessive Heat Build-Up When Using Ultrasonic Cell Disruptor Systems

Many research studies in biotechnology require physical disintegration of cells in order to examine materials contained within them, including DNA, RNA, proteins, and chromatin, amongst others. Whilst there are several physical methods to break open a cell by destroying its cell wall, such as mechanical disruption, freeze/thaw cycles, manual grinning, and liquid homogenization, using an ultrasonic cell disruptor is one of the most favoured ones owing to its greater flexibility to process a range of sample volumes.

Though ultrasonication is widely used in laboratory as well as production settings to disrupt cell membranes and walls of varying sensitivities, it is important to consider that ultrasonic cell disruption can generate substantial heat rapidly, which has a tendency to negatively affect the sample in two ways. Firstly, excessive heating can degrade the sample itself. Secondly, it can restrain cavitation to some extent.

As a result, effective care must be taken to take care of the excessive heat build-up when using ultrasonic cell disruptor systems. Following are the methods by which operators can prevent the same:

1. Employ the Adjustable Pulse Mode

When using the direct sonication method i.e. when the probe/microtip is directly immersed into the sample, long sonication bursts can result in immense heat gain in the area near the titanium tip. To avoid this, experts recommend using the adjustable pulse mode. This mode allows the user to set on and off times and the number of cycles for which the settings repeat. This preserves the integrity of the materials contained within the cells whilst allowing the cell wall to disintegrate, improving the reproducibility of the samples.

2. Combine the Pulse Mode with Ice Cooling

In case of extremely smaller volumes to be processed, operators should set the pulse mode depending on the cell structure’s sensitivity to ultrasonic cavitation and chill the samples on ice during every interval of the sonication cycle. This provides an appropriate balance between destroying the cell wall and not damaging the intracellular elements.

3. Use Chiller and Cup Horn Assembly

Compact chillers that directly attach to the cup horn assembly keep the samples present in multiple tubes cool during sonication cycles. Operators can set the chiller to run on a desired temperature which in turn maintains the temperature of the water in the cup horn reservoir and avoids overheating. Additionally, this saves time as the operator doesn’t have to manually keep the samples on an ice bath.

4. Place the Samples in Cooling Racks

Another method to maintain the consistency of all the samples (cellular suspensions) and avoid heat gain during ultrasonic cell disruption is to use cooling racks placed over ice bath or any other temperature-control sources. This results in excess heat getting continuously dissipated and hence greater reproducibility of your samples.

Depending on the type of samples to be processed, operators may have to choose the method that best suits their requirements of consistent samples, greater reproducibility, and more cavitation effectiveness.

Paresh Shah is a Director at Life-Care Equipments Pvt. Ltd., a leading manufacturer and distributor of a wide range of ultrasonic cleaning systems.