[3DEM] A question about ice thickness of cryo-EM

[Yifan Cheng]

Hi

Well, the ice can be very very very thick no matter what grids you use. 
Did you ever get cryo grids which is too thick to be seen through?

What you can do to measure the ice thickness is to burn a small hole in 
the middle of the ice. Then tilt you holder to a high tilt say 60 degree 
and measure the size of the hole. This can tell you how thick is your 
ice. Then you can calibrate it with your CCD camera by measure the 
counts over an empty hole and over ice. Next time just by comparing the 
CCD counts over ice and empty hole will give you some fairly good 
estimation about your ice thickness. Good luck

Yifan



Hu, Guobin wrote:

> Hi colleagues,
> 
>  
> 
> For our image analysis, we need to estimate the maximum ice thickness in 
> our cryo-EM specimen on 3.5/1 quantifoil grids. We may be able to 
> estimate that based on the thickness of carbon foil. As indicated by the 
> quantifoil product catalogue, the standard thickness of carbon foil is 
> 12 nm. While observations of our cryo-EM micrographs have suggested that 
> the thickness of carbon foil is definitely much larger than 12 nm. Does 
> anybody have an idea of what the maximum thickness of ice could be on 
> quantifoil grids (3.5/1)?
> 
> Thanks for help!
> 
> Guobin Hu
> 
>  
> 
>  
> 

-- 

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Yifan Cheng, Ph.D.
Department of Cell Biology, Harvard Medical School
240 Longwood Avenue, Boston, MA 02115, USA
Phone: 1-617-432-4095 (office), 432-4097 (wet lab),
              432-4708 (EM lab), 432-4107 (computer lab);
Fax:   1-617-432-1144 (department)
email: Yifan_Cheng at hms.harvard.edu
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