Sticky crystals: Difference between revisions

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Crystal harvesting out of native crystallization drops (hanging- and/or sitting-drop geometries) can sometimes be severely hampered by the propensity of crystals to stick to their crystallization surface. Here are some tips on how to approach the problem:
Crystal harvesting out of native crystallization drops (hanging- and/or sitting-drop geometries) can sometimes be severely hampered by the propensity of crystals to stick to their crystallization surface. Here are some tips on how to approach the problem:


 
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OPERATE ON THE PLASTIC RATHER THAN ON THE CRYSTAL!
OPERATE ON THE PLASTIC RATHER THAN ON THE CRYSTAL!
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Take a sturdy needle (like one of the microneedles from a Hampton kit, or a very thin syringe needle, or an accupuncture needle) and stick the needle into the plastic a bit away from the crystal. Push hard. If you’re using polarizers, you may be abe to visualize the stress forces in the plastic by the shifting of the colors. The basic idea is to stress the plastic under the crystal without touching the crystal in any way. By digging and twisting, one can generate little movements across the plastic which can be enough to free the crystal. Sometimes you have to push quite hard, and to wiggle the needle a bit. Beware, however, as the needle can slip and ruin the crystallization drop.  
Take a sturdy needle (like one of the microneedles from a Hampton kit, or a very thin syringe needle, or an accupuncture needle) and stick the needle into the plastic a bit away from the crystal. Push hard. If you’re using polarizers, you may be abe to visualize the stress forces in the plastic by the shifting of the colors. The basic idea is to stress the plastic under the crystal without touching the crystal in any way. By digging and twisting, one can generate little movements across the plastic which can be enough to free the crystal. Sometimes you have to push quite hard, and to wiggle the needle a bit. Beware, however, as the needle can slip and ruin the crystallization drop.  


 
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COAT THE CRYSTALLIZATION SURFACE WITH A THIN LAYER OF GREASE
COAT THE CRYSTALLIZATION SURFACE WITH A THIN LAYER OF GREASE
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If working with the 'sitting-drop' geometry, one can coat the sitting drop depressions with a thin layer of vacuum grease. You only need a very thin layer of the grease (i.e. keep wiping off with a KimWipe until the grease is almost completely gone). Upon crystal harvesting, the crystals will have the tendency to slide right off the grease.
If working with the 'sitting-drop' geometry, one can coat the sitting drop depressions with a thin layer of vacuum grease. You only need a very thin layer of the grease (i.e. keep wiping off with a KimWipe until the grease is almost completely gone). Upon crystal harvesting, the crystals will have the tendency to slide right off the grease.
One may opt for Vaseline or petroleum jelly rather than silicone-based grease.  
One may opt for Vaseline or petroleum jelly rather than silicone-based grease.  


 
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COAT THE CRYSTALLIZATION SURFACE WITH SILICON
COAT THE CRYSTALLIZATION SURFACE WITH SILICON
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You can try various siliconizing fluids such as AquaSil (Hampton Research).  Such a product will not melt the plastic of the crystallization plate as opposed to eg. Repelcote.
You can try various siliconizing fluids such as AquaSil (Hampton Research).  Such a product will not melt the plastic of the crystallization plate as opposed to eg. Repelcote.


 
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CHANGE CRYSTALLIZATION PLATE
CHANGE CRYSTALLIZATION PLATE
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One may want to try plates made from COC (cyclic olefins), such as the "UVP" plates made by SwissCi. They are less sticky than polystyrene plates. COC is halfway between polystyrene and polypropylene.  Polypropylene is even less sticky than COC but is not rigid, therefore not recommended for crystallization robots.  You can get plates made of "clarified polypropylene" from Emerald, and you can also get polypropylene "bridges" that you place in Linbro wells.  I think Hampton still sells them.
One may want to try plates made from COC (cyclic olefins), such as the "UVP" plates made by SwissCi. They are less sticky than polystyrene plates. COC is halfway between polystyrene and polypropylene.  Polypropylene is even less sticky than COC but is not rigid, therefore not recommended for crystallization robots.  You can get plates made of "clarified polypropylene" from Emerald, and you can also get polypropylene "bridges" that you place in Linbro wells.  I think Hampton still sells them.


 
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CRYSTAL BOWLING
CRYSTAL BOWLING
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If you have good and bad crystals in the same drop, one may try to push crummy crystals into a good crystal, thus creating the necessary leverage to release the useful crystals from their growth position.  
If you have good and bad crystals in the same drop, one may try to push crummy crystals into a good crystal, thus creating the necessary leverage to release the useful crystals from their growth position.  


TRY CRYSTALLIZATION WITH AGAROSE AS AN ADDITIVE
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CRYSTALLIZATION WITH AGAROSE AS AN ADDITIVE
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Crystals grown in the presence of 0.1-0.2 % (w/v) agarose will grow inside the soft agarose gel.
Crystals grown in the presence of 0.1-0.2 % (w/v) agarose will grow inside the soft agarose gel.
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PMID: 12351881
PMID: 12351881


 
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'FLOATING-DROP' CRYSTALLIZATION METHOD  
'FLOATING-DROP' CRYSTALLIZATION METHOD  
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References:
References:
-Application of a two-liquid system to sitting-drop vapour-diffusion protein crystallization. -Adachi, H. et al, Acta Cryst. (2003) D59, 194-196
-Application of a two-liquid system to sitting-drop vapour-diffusion protein crystallization. -Adachi, H. et al, Acta Cryst. (2003) D59, 194-196
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HR2-797        100% Fluorinert FC-70 Fluid    100 ml
HR2-797        100% Fluorinert FC-70 Fluid    100 ml


 
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MICROSEEDING   
MICROSEEDING   
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This method should allow better control of nucleation events in case the  
This method should allow better control of nucleation events in case the crystallization surface


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DRY-ICE trick
DRY-ICE trick
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Put a small piece of dry ice on the opposite side of the plastic from the crystal.  Perhaps the difference in thermal expansive coefficient will let the crystal(s) break away.  Don't overdo it though.  This is a trick that Gary Gilliland taught me.
Put a small piece of dry ice on the opposite side of the plastic from the crystal.  Perhaps the difference in thermal expansive coefficient will let the crystal(s) break away.  Don't overdo it though.   


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‘IN-PLATE’ DIFFRACTION EXPERIMENTS
‘IN-PLATE’ DIFFRACTION EXPERIMENTS
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-i hope i understood correctly, but basically leave the crystal in-situ and put the whole ensemble in an x-ray beam.  somehow.  you may see plastic scatter.  never tried it, all theoretical.
-i hope i understood correctly, but basically leave the crystal in-situ and put the whole ensemble in an x-ray beam.  somehow.  you may see plastic scatter.  never tried it, all theoretical.
perhaps custom-cut a tray so you can break the well away when the xtal grows.  or put something down there to grow on, then pick it out... would love to know if any of that works!
perhaps custom-cut a tray so you can break the well away when the xtal grows.  or put something down there to grow on, then pick it out... would love to know if any of that works!
-You might want to contact Luc Ferrer from ESRF in Grenoble or read his publications. I know they were developping robotisation for in plate shooting, but you probably will need to set up new trials in a particular type of plate.
-You might want to contact Luc Ferrer from ESRF in Grenoble or read his publications. I know they were developping robotisation for in plate shooting, but you probably will need to set up new trials in a particular type of plate.
-You can collect data on your crystal still in the drop, on our beamline (FIP-BM30A at the ESRF) if you are interested. Provided space group is not P1.... We do that routinely.
-You can collect data on your crystal still in the drop, on our beamline (FIP-BM30A at the ESRF) if you are interested. Provided space group is not P1.... We do that routinely.
MITEGEN MICROTOOLS
 
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MiTeGen MICROTOOLS
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The MiTeGen microtools kit:
The MiTeGen microtools kit:
http://mitegen.com/products/microtools/microtools_kit1.shtml
http://mitegen.com/products/microtools/microtools_kit1.shtml
comes with a "MicroSaw", which is a 10-micron thick kapton saw that is intended for this purpose. That is, you don't pry the crystal off the surface, but rather rest this saw against the surface, bring it over to the edge of the stuck crystal and then work it back and forth until you have cut underneath the crystal.
comes with a "MicroSaw", which is a 10-micron thick kapton saw that is intended for this purpose. That is, you don't pry the crystal off the surface, but rather rest this saw against the surface, bring it over to the edge of the stuck crystal and then work it back and forth until you have cut underneath the crystal.
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PIPETTING techniques
PIPETTING techniques
I had a similar story like yours.Then I added a drop of 10ul simulated mother liquot which contains much higher concentrations of all components in the normal mother liquot. Sometimes, the crystals attached to the plastic would float to the  surface. If not, take another 10ul, but blew it to the bottom plastic with a pippetman back and forth, and some crystals would also leave the plastic(But you have to be very careful to do this.)
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Add a drop of 10ul mother liquor to the crystallization drop. Sometimes, the crystals attached to the plastic would float to the  surface. If not, take another 10ul and pipet it in and out the drop as close as possible to the bottom.  Some crystals would also leave the plastic.  
GROW THE CRYSTALS ON A MICROTOOL MESH
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SONICATION
SONICATION
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For my PhD I once sonicated crystals off a glass surface; diffraction was fine; apparently this was the standard approach for papain when Jan Drenth solved it long ago.
One may want to sonicate crystals off its crystallization surface; apparently this was the standard approach for papain when Jan Drenth determined the structure a long time ago.
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