BioSAXS Beamline

The BioSAXS beamline is a high-flux beamline dedicated to solution small angle scattering experiments at the Australian Synchrotron. Part of the BR-GHT suite of beamlines, BioSAXS is entering operations and the content of this page will change as development of the beamline continues. The primary role of the beamline it to take 2D small angle scattering patterns on solution samples, either equilibrated or evolving, using a Pilatus3S 2M area detector. The aim of the beamline is to provide a streamlined and largely automated experience from sample presentation to data capture and processing.

If you have any questions about the beamline or its capabilities in the context of your science, please contact the beamline team at as-biosaxs@ansto.gov.au. The BioSAXS team strongly encourages all users, including experienced users, to contact the beamline team prior to submitting proposals to discuss their experiments. BioSAXS is a new beamline with new systems and not everything may work as you expect from your prior experience on other beamlines. If you’re new to SAXS and are looking for useful links/guides, please visit the SAXS/WAXS beamline wiki at this link, where you can order a free copy of the Anton Paar SAXS Guide and see some of our previous beamline workshops.

Beamline Technical Details

Source – BioSAXS has a superconducting undulator source, providing an X-ray beam of flux on the order of 10¹⁴ photons/s at the sample position. The undulator is optimized for a photon energy of 12.0 keV and this will be the primary photon energy used for experiments. If you require other photon energies, please discuss this with the beamline team prior to submitting your proposal as your experiment may be more suited to the SAXS/WAXS beamline, on which the undulator has a wider accessible energy range.

Monochromator – The use of a double multilayer monochromator increases the flux relative to a standard double crystal monochromator. The multilayer on BioSAXS comprises B₄C/Mo layers and an energy bandpass (dE/E) of 1.0%. As a result, BioSAXS is not suited to anomalous SAXS experiments, which rely on finer energy resolution. If you wish to perform anomalous SAXS measurements, please reach out to the SAXS/WAXS beamline team to discuss your requirements.

Detector – BioSAXS has a Pilatus3X 2M detector, similar to that deployed on the SAXS/WAXS beamline. The detector is mounted on a translation stage in a large vacuum vessel, allowing it to reach distances of ~700-7000 mm from the sample position. With a photon energy of 12.0 keV, this should allow a minimum q of ~0.003 Å^-1 at the longest sample-detector distance and a maximum q of ~2.4 Å^-1 at the shortest sample-detector distance.

Sample Environments

As the beamline enters user operations, the following sample environments will be supported:

Coflow – Sample autoloader operating in Coflow mode, with a sheath of buffer/water surrounding the sample being presented to the beam to reduce radiation damage.[Kirby, N. et al. Acta Crystallogr., Sect. D: Biol. Crystallogr. 2016, 72, 1254 & Ryan, T. M. et al. Appl. Crystallogr. 2018, 51, 97] Please note that the Coflow is compatible with fully liquid samples only, no solids/gels/precipitates will be compatible with the Coflow. If your samples contain solids, precipitates, or are viscous please contact the beamline team to discuss your experiments. In the first instance, we will direct you to the most appropriate alternative sample environments to perform your experiments. Coflow will operate in two modes as described below, please indicate which mode(s) are required in your proposal:

·         Batch mode – For measurements on equilibrated samples. Samples are presented in 96 well plates (volume up to 100 µL) or 384 well plates (volume up to 45 µL). Corresponding buffers/solvent (minimum 2.0 mL total) are loaded in a separate 96 deep-well plate, which will accept volumes up to 1.3 mL in each well. The buffer is loaded into the top of the Coflow cell, which is drawn through the measurement capillary as the sample is injected to act as the sheath fluid.

·         SEC mode – For measurements requiring separation of components in solution by size. Samples are presented in 96 well plates (volume up to 100 µL) or 384 well plates (volume up to 45 µL). Buffers/eluent are loaded into Schott bottles and circulated through a column by an HPLC pump and through the Coflow cell by separate pumps. Samples are loaded into the column loop and the eluent from the column flows through the Coflow cell. UV-detection close to the Coflow cell gives a secondary indication of sample elution. Column containment accepts standard 5-150 columns and the larger 10-300 columns. We advise that users supply their own clean columns and have tested their elution protocol prior to attending the beamline.

Note that both Coflow operational modes require you to have substantial quantities of the buffer/solvent used to prepare your samples in order to measure them. Make sure that you reserve a sufficient quantity of the same solvent/buffer used to prepare your samples for successful Coflow measurements with good background subtraction. Please outline the full composition of your buffers/solvents to the beamline team, particularly if they contain chemicals beyond standard buffer components  (e.g., adjuvants, cofactors, substrates, additives etc.). Some of these chemicals are subject to beam damage, which can lead to capillary fouling if they are in the sheath buffer and will significantly reduce the quality of your measurements, if not make them meaningless. The full chemical composition of your buffers must be listed in the Experimental Authorisation form for assessment of their compatibility with he Coflow system and for chemical safety assessment.

Capillary Rack – Capillary rack with 9 positions that will take standard 1.5 mm diameter capillaries available from Hilgenberg/Charles Supper. Users are expected to supply their own capillaries for measurements using the capillary rack. Each capillary position is heated by a peltier element, providing temperature control within temperature ranges for standard measurements in aqueous solution (5-80 °C).

Linkam Hotstage – Heating stage with a single capillary position. The Linkam hotstage provides a wider temperature range (up to 350 °C) for measurements on fluid samples and programmable temperature ramping schemes to be sequenced with data acquisition.

Flowthrough Capillary – For dynamic measurements on evolving systems circulated through a capillary using a peristaltic pump. Sample volumes will need to be on the order of 15-20 mL to ensure sufficient volume for circulation though the capillary. Several modes of operation are possible with this sample environment including:

·         Free-hanging capillary – Capillary in the X-ray beam under ambient hutch conditions.

·         Temperature-controlled capillary – Capillary mount under temperature control by circulating water bath.

·         CHROLIS light source – Capillary mount under temperature control and with secondary illumination perpendicular to the X-ray beam by UV-Vis-NIR LEDs. Details on the illumination wavelengths available are given below.

·         BYO light source – If you wish to use your own in-house light source (LED, Laser etc.) to stimulate change in a sample, please contact the beamline team immediately at as-biosaxs@ansto.gov.au. Appropriate arrangements will need to be made with the synchrotron safety team before a user-supplied light source will be allowed to be used on site. The best time to confirm this is before submitting your proposal, otherwise we cannot guarantee the technical feasibility of your experiment.

BioSAXS has a Thorlabs CHROLIS-1 6-wavelength high-power LED source fitted with the following LEDs coupled into a liquid light guide. Details below are sourced from the CHROLIS-1 manual supplied by Thorlabs and the spectra below are from the Thorlabs website.

Upcoming Sample Environments in 2024

The following sample environments will be commissioned during our first year of operations and more details will be provided when they come online and available to be selected in proposals. They are not currently available:

In Situ Magnetic Fields – For measurements on samples susceptible to magnetic fields.

Stopped-flow Measurements – For fast time-resolved studies on evolving samples.

Shear Cell – For oriented SAXS measurements on anisotropic samples in solution, sheared with the velocity gradient parallel to the X-ray beam.

Rheometer – For tandem rheological and SAXS measurements in an Anton Paar rheometer with a Couette cell.

Clarification on applying for BioSAXS or SAXS/WAXS beamtime in 2024/2 

• For solutions that are automatically loaded please apply for BioSAXS beamtime where the Coflow Autoloader is used. Exceptions include samples or experiment design not feasible for BioSAXS (such as anomalous scattering, photon energy requirement (>15 KeV), high viscosity, etc.) for which the SAXS/WAXS beamline will maintain a limited capability for automatic liquid handling.    

• SEC-SAXS for proteins should be on BioSAXS 

• Batch measurements for samples in solution should typically be on the BioSAXS beamline 

• Solution samples in static capillaries can be used on BioSAXS or SAXS/WAXS 

• Contact staff at as-scattering@ansto.gov.au for guidance on specific experiment plans and beamline suitability