MiTeGen’s patented MicroRT™ capillary system is the answer for room temperature diffraction screening and data collection. Go from a crystal in a drop to a crystal in the X-ray beam at room temperature quickly and easily. Collect room and low temperature data from the same crystal to evaluate your crystal and cryopreservation protocol. And use saturated salt solutions to controllably dehydrate crystals and improve their order.

Why collect diffraction data at room temperature?

Room temperature screening is especially important in protein crystallography. Roughly 98% of low-temperature data sets collected on structural biology beam lines do not yield diffraction data of sufficient quality to determine a structure. Room temperature measurements are essential to determine whether the cause of poor diffraction is poor as-grown crystal quality, sample damage caused by ligand and/or cryoprotectant soaks, and/or sample damage caused by the flash cooling process itself. Far too much effort is wasted searching for cryoprotection conditions for crystals that are poorly ordered to start with. Far too much synchrotron beam time is wasted on crystals that should have been rejected in home source screening.

The MicroRT system provides an extremely cost effective tool for increasing the efficiency of your diffraction pipeline.

Design 

In the MicroRT system, a sample is mounted on, e.g., a MicroMount or MicroGripper that is inserted into a goniometer base, just as for cryocrystallography. A MicroRT capillary is then drawn over the sample and onto the base.

Standard 10 μm wall glass X-ray capillaries are replaced with 25 μm wall transparent polymer capillaries that are presealed at one end. Although the polymer is thicker, it’s C and H scatter X-rays much more weakly than glass’s Si and O, so overall background scatter is reduced by 60%. The capillary diameter, 2 mm, is much larger than your crystal and MicroMount, and mates with our modified goniometer bases that both hold the MicroMount and capture the tubing.

Unlike with conventional X-ray capillary mounting, the MicroRT capillary simply provides a protective cover, and the sample makes no contact with it.

To prepare a sample for room temperature measurements:

• Using a gel-loading pipette tip, inject humidity-stabilizing liquid (e.g., mother liquor or well solution) down into the capillary toward its sealed end.
• Insert your MicroMount / MicroGripper / MicroLoop / MicroMesh into a goniometer base, and then mount your sample as you would for cryocrystallography.
• Draw the capillary tubing down over the sample and mount and onto the narrowed neck of the goniometer base.

Unlike in conventional capillary mounting, the sample is held away from the capillary wall and so there is no liquid/wall optical distortion. Sample imaging is excellent, and the sample can be aligned in the X-ray beam using standard autoalignment software.

Once you’ve collected your room temperature frames, just pop off the tubing, plunge the MicroMount in your liquid cryogen, and you’re ready to collect a low-temperature data set. Or else soak your crystal in the next solution, pop the plastic tubing back on, and repeat until you’ve checked out each solution.

The MicroRT system also provides an easy way to controllably dehydrate your samples, which can yield significant improvements in diffraction quality. See our technical notes for details.

Features 

• Allows rapid screening of crystals at room temperature, to help maximize the efficiency of your crystallography pipeline.
• Easy sample mounting with little risk of crystal loss or damage.
• Easy collection of both room and low-temperature data from the same sample.
• Easy sample visualization and alignment, especially for small crystals.
• Capillary tubing is easily cut and sealed , and gives significantly less background X-ray scatter than glass capillaries.
• One size capillary fits all , and capillaries are reusable, lowering your cost per measurement.

MicroRT™ Room Temperature Starter Kit #1

Get Started Preparing Samples for Room Temperature Screening

• one (1) MicroRT™ Tubing Kit (RT-T1)
• one (1) MicroRT™ Aligner (RTA-1)
• ten (10) Reusable goniometer bases (GB-B3S-R)
• one (1) box of 20 Dual-Thickness MicroMounts™ (M2-L18SP-A2)
• one (1) pair of serrated-end tweezers (TW-1)

Each bottle of MicroRT™ Capillaries (RT-T1) contains 20 – 1.5″ (37 mm) long clear polyester capillaries sealed at one end, an extra-keen razor blade for cutting the tubes to a desired length, and a tiny tube of grease for lubricating the base.

MicroRT™ Room Temperature Starter Kit #2

A more complete kit offering including additional materials such as a low viscosity oil, smaller MicroMounts, and saturated salt solutions. This kit allows users to do more with the system such as work with smaller crystals and perform dehydration testing.

• one (1) MicroRT™ Tubing Kit (RT-T1)
• one (1) MicroRT™ Aligner (RTA-1)
• two (2) boxes of 20 Dual-Thickness MicroMounts™ (M2-L18SP-A1, M2-L18SP-A2)
• one (1) pair of serrated-end tweezers (TW-1)
• twenty (20) Reusable Goniometer Bases (GB-B3S-R-20)
• one (1) Set Dehydration Salts (M-CO-121)
• one (1) Low Viscosity CryoOil (5 ml) (LVCO-5)
• one (1) Pack Gel Loading Pipette Tips (200 tips) (GLPT-1)

Now using Mitegen’s patented MicroRT system is even easier. Our new MicroRT Aligner makes sliding the capillary tubing past your crystal and onto our goniometer bases a breeze. No need to use a microscope or magnifier and no worries about shaky hands causing you to bump your crystal.
Inject your MicroRT capillary with your mother liquor or other humidity stabilizing solution, and place it on the left side of the aligner. Harvest your crystal using a MicroMount (or any of our other mounts) inserted into one of our goniometer bases. Attach the base to a standard magnetic wand.

As shown in the video below, place your crystal and wand in the right side of the aligner. Then simply slide the MicroRT capillary down the precisely designed channel and onto the goniometer base.