Reducing sample consumption for serial crystallography using acoustic drop ejection.

Gabriel Leen,Agata Butryn,Ali Ebrahim,John H. Beale,Peter Docker,Bradley Davy,Robin L. Owen,Allen M. Orville,Danny Axford,Pierre Aller

doi:10.1107/s1600577519009329

Abstract

Efficient sample delivery is an essential aspect of serial crystallography at both synchrotrons and X-ray free-electron lasers. Rastering fixed target chips through the X-ray beam is an efficient method for serial delivery from the perspectives of both sample consumption and beam time usage. Here, an approach for loading fixed targets using acoustic drop ejection is presented that does not compromise crystal quality, can reduce sample consumption by more than an order of magnitude and allows serial diffraction to be collected from a larger proportion of the crystals in the slurry.

Highlights

Serial femtosecond crystallography (SFX) at X-ray free-electron lasers (XFELs) has become an important facet of the crystallographers’ toolbox, allowing both time-resolved and ground-state measurements of X-ray sensitive samples (Schlichting, 2015)
Acoustic dispensing provides a means of reducing sample consumption for serial crystallography without compromising crystal quality with high-quality diffraction observed using both loading approaches
Acoustic dispensing has been previously exploited in the context of sample delivery, whereas here it is used for loading fixed targets that are subsequently passed to the beamline

Summary

Introduction

Serial femtosecond crystallography (SFX) at X-ray free-electron lasers (XFELs) has become an important facet of the crystallographers’ toolbox, allowing both time-resolved and ground-state measurements of X-ray sensitive samples (Schlichting, 2015). Several approaches have been developed to meet this challenge ranging from liquid jets to high viscosity extruders, ondemand droplet injectors coupled to a tape drive, and fixed targets (Grunbein & Kovacs, 2019; Martiel et al, 2019). The sample requirements for a serial experiment are often an unwelcome surprise for the first-time user of SFX or SSX, as usually only a single ‘still’ image is collected from each crystal. This is reflected by developments to reduce sample con- is loaded into a cartridge which has a dispensing aperture sumption for serial experiments such as flow-focusing for in- ranging from 30 mm to 150 mm in diameter.

Methods

Sample preparation

X-ray data collection

Results

Discussion

Funding information