Quantifoil

What is Quantifoil? A Critical Support Film for Cryo-Electron Microscopy

Quantifoil is a high-precision, perforated support film made of carbon or other materials (such as gold) with meticulously defined hole size, shape, spacing, and arrangement. It is designed to be mounted on Transmission Electron Microscopy (TEM) grids and serves as a support layer for biological or material science samples during high-resolution imaging, particularly in cryo-electron microscopy (cryo-EM).

🔬 Why Use Quantifoil?

Unlike conventional holey carbon films, which are irregular and randomly perforated, Quantifoil films feature a repeatable, grid-like pattern of circular or square holes with exact specifications. These holes are laser-milled or lithographically produced, ensuring exceptional reproducibility and uniformity across the support.

This unique structural regularity provides multiple critical advantages:

• Facilitates Automated Data Collection:
  The consistent geometry of the perforations allows cryo-EM systems to automatically locate holes and optimize image acquisition workflows. This greatly improves throughput and reduces manual intervention.
• Improves Sample Consistency and Ice Quality:
  The regular spacing and high open-area ratio support even distribution of thin layers of vitrified ice, which is crucial for high-resolution imaging and reducing sample variability.
• Minimizes Background Noise and Support Interference:
  Since the sample is suspended over well-defined holes rather than resting on a continuous carbon layer, electron scattering is minimized. This enhances signal-to-noise ratio and preserves fine structural details.

💎 Structural Benefits of Quantifoil

Quantifoil films are known for their:

• High Mechanical Stability: Ensures durability during freezing and handling
• Ultra-clean Surface: Reduces contamination that can affect imaging
• Customizable Designs: Available with varying hole diameters (e.g., 1.2 μm, 2 μm), spacing, and geometries
• Compatibility: Can be coated with thin amorphous carbon layers, gold, or functional materials for specific experimental needs

🧪 Applications in Cryo-EM and Advanced Microscopy

Quantifoil grids are widely used in:

• ✅ Cryo-Electron Microscopy (Cryo-EM): Imaging of biomolecular complexes in vitrified ice
• ✅ Electron Diffraction (ED): For structural determination of crystalline materials
• ✅ Electron Energy Loss Spectroscopy (EELS): Elemental and bonding information in nanoscale samples
• ✅ Dark-Field Imaging & Phase Contrast EM
• ✅ Low-Energy Electron Point Source (LEEPS) Microscopy

These applications benefit from the minimal background signal, uniform sample support, and mechanical robustness offered by Quantifoil films.

🧬 Use Cases: From Proteins to Nanoparticles

Quantifoil is especially suitable for imaging:

• Biological macromolecules (e.g., protein complexes, ribosomes, viruses)
• Nanoparticles and nanomaterials suspended in amorphous ice
• Micrometer-sized powder particles for materials science studies
• Samples requiring ultra-thin amorphous carbon support

Its use has become standard in structural biology labs worldwide, enabling atomic-resolution cryo-EM studies that were previously impossible with traditional carbon films.

📦 Available Formats

Quantifoil films come in a variety of formats:

• Hole types: R 1.2/1.3, R 2/2, R 2/1, S 7/2, etc.
• Substrate materials: Copper, gold, nickel, molybdenum
• Film types: Standard carbon, ultrathin carbon, gold film (UltrAuFoil)
• Coating options: With or without amorphous carbon layers