This in-solution Biological Small & Wide angle X-ray Scattering (BioSAXS/WAXS) system allows native macromolecules to be studied, ranging from individual proteins to large complexes, in solution and under nearly physiological conditions. It allows the automatic transfer of the samples from a storage unit to an exposure unit in a highly controlled environment.
Controlled sample temperature
BioSAXS is a highly optimized sample changer robot working with standard SBS well plates:
The sample storage unit can be loaded with a standard SBS well plate for sample solutions and one Eppendorf strip for buffer solutions. The SBS plate type is recognized automatically.
The height of sample liquid within the individual well plates is recognized automatically.
The entire cycle, including sample loading, unloading and capillary cleaning is done within 50 seconds. This performance is reached for all sample viscosities: the BioSAXS sample changer automatically adjusts the transfer to the sample viscosity in order to achieve a duty cycle close to 50 seconds.
All calibrations and adjustments for a new exposure capillary are automatic: the BioSAXS sample changer adjusts the dead volume, measures the capillary diameter, identifies the sample position on the screen and adjusts the focus positions for both capillary walls. (Adam Round, 2014)
The pipetting needle and the exposure cell capillary undergo automatic cleaning within each cycle. This integrated cleaning process considerably improves the workflow, giving faster operation, better and more reliable cleaning compared to classical approaches, e.g. manual cleaning. (Adam Round, 2014)
“…, the operation of the Sample Changer was proven to be highly reliable: at the EMBL@PETRA-III P12 beamline over 80, 000 samples were loaded and measured during 2013, with only five failures owing to various reasons, corresponding to a failure rate of below 0.01%.” (Adam Round, 2014)
The BioSAXS automatic sample changer is entirely designed for highly controlled SAXS experiments:
The user can set the sample temperature for two environments: 4 to 40°C (±1°C) for the sample storage unit, and 2 to 60°C (±1°C) for the sample exposure unit.
The sample transfer process is adapted to the selected viscosity, i.e. a BioSAXS algorithm calculates sample pipetting volumes according to the selected viscosity regime.
In “static sample exposure” mode the position of liquid sample within the exposure cell capillary is stabilized via pressure control. The same pressure control allows channeling the sample through the capillary with defined speed. Constant sample flow speed during exposure helps to keep the sample’s x-ray dose constant over time. During a “flow sample exposure” experiment the user can set flow speeds between 0.05 µL/s to 20 µL/s. (Adam Round, 2014)
The temperature regulated sample storage slot can receive numerous types of sample holders: 96-well and deep-well SBS microplates, strips of wells (4 x 8 wells Eppendorf strips) and individual wells (4 x 3 individual 1.5 mL wells).
Furthermore, it is possible to fit the BioSAXS automatic sample changer for another type of sample holder. Please contact us to estimate the technical possibilities.
The sample holders can be installed or removed by opening the top cover of the BioSAXS Sample Changer Robot.
The Sample Exposure Unit (SEU) is composed of an exposure cell housing, a video microscope and a Pipetting System.
The Exposure Cell housing is a temperature regulated and vacuum-tight chamber that hosts the exposure cell, a quartz capillary. The capillary is mounted in a metallic support, the so-called capillary pod. The capillary pod can be exchanged within minutes, making the Sample Exposure Unit maintenance friendly.
The video microscope is associated with a lighting system that allows capillary and sample visualization. The video microscope images are exploited by the control software for most of the automated functions and calibrations; it also offers direct sample visualization to the user.
The sample transfer
The liquid samples are kept inside the temperature controlled sample storage container (violet).
It moves horizontally (red arrows) and positions under the syringe (i.e. pipetting needle) for sample loading.
The robot automatically fits the syringe to the type of sample holder used. The user has simply to launch the sample loading process. After sample disposal the cleaning station (green) moves up in order to clean the syringe, the capillary and any of the connecting tubing.
During the sample loading process the liquid sample passes through the syringe (yellow) and very short tubing (green) before arriving in the exposure head (violet).
The capillary and its content are visualized in situ by means of the video microscope (black).
After data collection the irradiated sample is automatically send to the sample disposal container. However, BioSAXS can also be set to recover the sample and bring it back to the sample storage unit. Thus, the user can recover the sample to its initial place or in any other of the available sample wells. A direct consequence of the sample recovery functionality is the possibility of in situ sample mixing.
“The Sample Changer can realize the transfer of a given volume of solution from one well to another. If the destination well already contains solution then the depth of liquid inside is detected. To improve mixing of two liquids, the needle moves up through the liquid in the destination well while dispensing the solution. Thorough mixing can be programed, typically after a transfer, by pipetting a small volume into the needle and back to the well a requested number of times.” (Adam Round, 2014)
BioSAXS can be equipped with a retractable SAXS/WAXS Sample Exposure Unit. This is interesting if users want to use other types of sample supports, e.g. microfluidic plates.
| Performances | |
| Solution transfer volume | 5 to 200 µL |
| Typical cycle time | 50 s |
| – Loading / unloading | 15 s / 15 s |
| – Cleaning (wash, rinse, dry) | 20 s |
| Sample Containers | |
| – 96-wells microplates (SBS) | |
| – 96-deep well microplates (SBS) | |
| – 4 x 8 wells Eppendorf strips (200µL) | |
| – 4 x 3 individual 1.5 mL wells (buffers) | |
| – Customized holders | |
| Controls | |
| Sample exposure modes | – Static – Flow (0.05 to 20µL/s; viscosity dep.) |
| Temperature Control | |
| – Exposure | 2 to 60 °C (±1°C) |
| – Storage | 4 to 40 °C (±1°C) |
| Control panel | Video assisted automatic liquid positioning |
| Full remote control | TANGO, TINE, EPICS, Web services |
| Power | |
| 400 VAC | 7360 W |
| Dimensions (W,H,D) | |
| Main unit (robot) | 550 x 800 x 1100 mm3 |
| Fluid management rack | 837 x 576 x 900 mm3 |
| Control rack | 712 x 576 x 900 mm3 |
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