Micro-structured polymer fixed targets for serial crystallography at synchrotrons and XFELs.

Area of Science:

• Crystallography
• Materials Science
• Biophysics

Background:

• Fixed targets are crucial sample-delivery systems for serial crystallography at synchrotron and X-ray free-electron laser sources.
• Current polymer-based fixed targets lack the precision for aperture-aligned data collection, limiting their use to random crystal distribution.
• Silicon fixed targets enable precise, aperture-aligned data collection but may have limitations in other aspects.

Purpose of the Study:

• To present the fabrication and initial results of micro-structured polymer fixed targets (MISP chips).
• To demonstrate that polymer-based fixed targets can achieve the precision necessary for aperture-alignment strategies in serial crystallography.
• To explore the potential of MISP chips for optimizing crystal loading and data collection efficiency.

Main Methods:

• Fabrication of micro-structured polymer membranes with precise arrays of cavities and fiducial markers, integrated into a stabilization frame.
• Loading of micro-crystals into the cavities, with excess solution removal through base apertures.
• Utilizing fiducial markers for rapid aperture location calculation and a priori crystal location analysis due to optical transparency.

Main Results:

• MISP chips demonstrate the required precision for aperture-aligned data collection, similar to silicon targets.
• The chips exhibit low X-ray background and optical transparency, facilitating crystal analysis and optimizing hit rates.
• Optimal crystal loading is observed for sizes around 25 µm, with quality data collectible from crystals as small as 5 µm.

Conclusions:

• Polymer-based fixed targets, specifically MISP chips, can be fabricated with the precision needed for advanced data collection strategies.
• MISP chips offer a promising, potentially more sustainable and cost-effective alternative for serial crystallography.
• Further development in mass fabrication is recommended to enhance the sustainability of MISP chips for broader use in crystallography facilities.