Cryogenic Electron Microscopy Methodologies as Analytical Tools for the Study of Self-Assembled Pharmaceutics

Area of Science:

• Pharmaceutical Science
• Materials Science
• Microscopy

Background:

• Pharmaceuticals often exist as viscous, non-aqueous dispersions of self-assembled molecular complexes.
• The efficacy of these formulations is frequently linked to their complex nanostructure.
• Direct imaging is essential for understanding nanostructure, but liquid systems pose challenges for electron microscopy.

Purpose of the Study:

• To review the state-of-the-art in imaging self-assembled complexes in pharmaceutical dispersions.
• To describe cryogenic electron microscopy techniques for analyzing pharmaceutical nanostructures.
• To highlight the applications, limitations, and best practices for these methods.

Main Methods:

• Cryogenic transmission electron microscopy (cryo-TEM)
• Cryogenic scanning electron microscopy (cryo-SEM)
• Direct imaging of liquid systems under high vacuum conditions.

Main Results:

• Cryo-TEM and cryo-SEM enable direct visualization of nanostructures in pharmaceutical dispersions.
• These techniques provide model-independent nanostructural information.
• Challenges include sample preparation, high vacuum compatibility, beam damage, and contrast issues.

Conclusions:

• Cryogenic electron microscopy is indispensable for characterizing the nanostructure of pharmaceutical self-assembled complexes.
• Understanding and mitigating methodological challenges are key to reliable analysis.
• These techniques are vital analytical tools for pharmaceutical development and quality control.