Effects of base temperature, immersion medium, and EM grid material on devitrification thresholds in cryogenic...

Area of Science:

• Structural biology
• Microscopy techniques
• Biophysics

Background:

• Cryo-correlative light and electron microscopy (cryo-CLEM) integrates molecular labeling with high-resolution structural data.
• A significant resolution gap exists between fluorescence microscopy and electron microscopy (EM).
• Cryogenic single-molecule localization microscopy (cryo-SMLM) aims to bridge this gap but faces challenges with laser-induced sample devitrification.

Purpose of the Study:

• To investigate factors influencing sample devitrification during cryo-SMLM.
• To identify optimal conditions for minimizing devitrification and maximizing laser tolerance.
• To provide quantitative insights for enhancing cryo-SMLM setup performance.

Main Methods:

• Finite element simulations to model heat transfer and devitrification.
• Experimental validation of simulation predictions.
• Systematic evaluation of base cooling temperature, immersion medium, and EM grid support materials (carbon vs. metallic).

Main Results:

• Cryo-immersion media improve heat dissipation for carbon supports.
• Metallic supports (gold, silver-coated) tolerate higher laser intensities, especially in cold nitrogen gas or vacuum.
• Gold supports show high laser thresholds at 640nm illumination.
• Metallic supports demonstrate efficient heat dissipation in vacuum cryostats.

Conclusions:

• Base cooling temperature, immersion medium, and support material critically affect cryo-SMLM laser tolerance.
• Metallic supports and cryo-immersion media are key for mitigating devitrification.
• Optimized cryo-SMLM setups using these findings can improve cryo-CLEM imaging resolution and data quality.