Critical point drying for scanning electron microscopy: a semi-automatic method of preparing biological specimens

Area of Science:

• Biological specimen preservation
• Electron microscopy sample preparation
• Materials science

Background:

• Critical point drying is a standard method for preparing biological specimens for microscopy.
• Specimen damage can occur during rapid heating or gas venting in critical point drying.
• Optimizing the drying process is crucial for maintaining structural integrity.

Purpose of the Study:

• To develop an improved critical point drying procedure for biological specimens.
• To balance specimen preservation with operational speed.
• To utilize carbon dioxide (CO2) as the transitional fluid.

Main Methods:

• Implementing slow, controlled rates for critical point bomb heating.
• Utilizing controlled gas venting procedures.
• Automating bomb heating with electronic controls.
• Monitoring gaseous CO2 venting with a gas flow meter.

Main Results:

• The developed procedure minimizes specimen damage during critical point drying.
• Achieved a balance between specimen preservation and operational efficiency.
• Successful application of controlled CO2 venting and heating.

Conclusions:

• Slow, controlled heating and venting are key to preserving biological specimens.
• The automated and monitored procedure offers a reliable method for critical point drying.
• This technique is suitable for preparing delicate biological samples for high-resolution imaging.