ANTcryo vs UltrAuFoil: Gold Cryo-EM Grid Comparison
Both ANTcryo and UltrAuFoil use gold grid substrates to reduce beam-induced motion. But the support film material — amorphous NiTi alloy vs pure gold foil — makes a significant difference in your cryo-EM workflow and data quality.
The Case for Gold Support Films
Traditional copper grids with carbon support films suffer from beam-induced motion (BIM) caused by differential thermal contraction between the grid and the support film. Gold grid substrates solve this by matching the thermal expansion coefficient of the support film, dramatically reducing BIM and improving high-resolution data quality.
UltrAuFoil (developed by Dr. Chris Russo and Lori Passmore at the MRC LMB) was a landmark innovation — replacing the carbon film with a pure gold foil on a gold grid. It demonstrated that all-gold grids can achieve significantly less beam-induced motion than carbon-on-copper.
ANTcryo takes a different approach: using a gold grid with an amorphous nickel-titanium alloy support film instead of pure gold foil. This combines the BIM reduction of gold grids with unique advantages of the NiTi alloy material.
Key Differences at a Glance
| Feature | ANTcryo (Au + NiTi Alloy) | UltrAuFoil (Au + Au Foil) |
|---|---|---|
| Grid Substrate | Gold (Au) | Gold (Au) |
| Support Film | Amorphous nickel-titanium alloy | Pure gold foil |
| Beam-Induced Motion | Reduced (Au grid + high conductivity) | Reduced (Au grid, matched CTE) |
| Protein Adsorption | ~10x lower than carbon | Lower than carbon, but higher than NiTi alloy |
| Glow Discharge Required | Yes (typically required) | Recommended (ready to use; glow discharge improves wetting) |
| Film Structure | Amorphous (no crystalline background) | Polycrystalline gold (may show diffraction rings) |
| Long-Term Stability | Amorphous — no grain coarsening | Gold foil may creep/coarsen over time |
| Resolution Improvement | +0.2 Å vs carbon (user data) | +0.2–0.4 Å vs carbon (published data) |
| Hole Patterns | 1.2/1.3 µm, 2.0/1.0 µm | 1.2/1.3 µm, 0.5/0.6 µm (R1.2/1.3, R0.5/0.6) |
| Film Thickness | 22 ± 3 nm | ~500 Å (≈ 50 nm) |
| Grid Options | Au 300/400 mesh, Cu 300 mesh | Au 300 mesh (R 1.2/1.3, R 0.6/1); Au 200 mesh (R 2/2) |
| Packaging | 50 pieces/box | Pack of 50 (standard) |
Why Researchers Switch from UltrAuFoil to ANTcryo
Thinner Support Films for Higher-Resolution Reconstructions
ANTcryo films are 22 ± 3 nm thick — roughly half the thickness of UltrAuFoil gold foil (~40–50 nm, i.e. ~500 Å). Thinner films produce less backscattering, which translates directly into higher signal-to-noise reconstructions — especially valuable when you push resolution below 2 Å.
Easier TEM Coma-Free Alignment
The amorphous NiTi alloy produces a continuous, symmetric halo (amorphous ring) under selected-area electron diffraction — the same reference amorphous carbon films provide. Coma-free alignment on the specimen area is straightforward. Pure gold foil, by contrast, shows discrete lattice spots in the diffraction pattern. You cannot align on the foil itself; you have to find an empty mesh region or a nearby reference point first, then return to the specimen area — a longer, more involved workflow.
Technical Deep Dive: Amorphous NiTi vs Pure Gold
Material Science Perspective
- • No grain boundaries → no diffraction artifacts
- • No crystalline order → isotropic surface properties
- • High conductivity → reduces electron charging
- • Naturally hydrophilic surface → self-wetting without treatment
- • Biocompatible with low protein binding affinity
- • Polycrystalline → may show grain boundaries
- • Matched CTE with Au grid → reduces differential BIM
- • Requires surface treatment (glow discharge) for hydrophilicity
- • Gold can undergo creep and grain coarsening under beam exposure
- • Proven track record in reducing beam-induced motion
When UltrAuFoil May Be the Better Choice
- •Your lab has established UltrAuFoil protocols and your samples consistently work well — if it's not broken, don't fix it.
- •You need the smallest hole sizes (e.g., R0.5/0.6 µm) that are not currently available in ANTcryo configurations.
- •Your institution has bulk purchasing agreements with Quantifoil/EMS that include UltrAuFoil.
Experience the Next Step in Gold Grid Technology
ANTcryo combines the BIM reduction of gold grids with self-wetting, low-adsorption NiTi alloy. Request a sample and compare for yourself.