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 |
| Self-Wetting | Yes — no glow discharge | No — glow discharge required |
| 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 | 25 ± 3 nm | ~500 nm (gold foil) |
| Grid Options | Au 300/400 mesh, Cu 300 mesh | Au 300 mesh |
| Packaging | 50 pieces/box | Varies by distributor |
Why Researchers Switch from UltrAuFoil to ANTcryo
Self-Wetting Saves Time and Improves Reproducibility
UltrAuFoil requires glow discharge before sample application. ANTcryo's NiTi alloy film is naturally hydrophilic — just apply sample and plunge. This eliminates a variable that can differ between glow discharge machines, operators, and sample types.
Lower Protein Adsorption Means More Usable Particles
While gold foils reduce adsorption compared to carbon, the amorphous NiTi alloy surface goes further — approximately 10x lower protein adsorption than carbon films. This translates directly to higher particle counts per micrograph and less time wasted on failed grids.
Amorphous Film Has No Crystalline Background
Pure gold foil is polycrystalline, which can produce diffraction rings or grain boundaries in your images. The amorphous NiTi alloy film has no crystalline structure, providing a clean background for particle picking and reconstruction.
Long-Term Structural Stability
Amorphous alloys are thermodynamically metastable but kinetically frozen — they do not undergo grain growth, coarsening, or creep at cryogenic temperatures. Gold foil can develop pinholes or change morphology over extended storage or under electron beam exposure.
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.