[3dem] Alkylamine vapor while glow discharge

[Willem Tichelaar]

Hi Eduardo,

Just in case somebody hasn't told you yet: glow-discharging in an amine 
atmosphere was, as far as I know, originally used to get nucleic acids 
adhered to carbon film; the reference is: Dubochet et al., J. Ultrastr. 
Res. 35 (1971) 147-167.

Since nucleic acids are negatively charged at neutral pH, they do not 
attach to a carbon film that has been glow-discharged in residual air, 
because this process results in a negatively charged surface.

As far as I know, Jacques advocated to carry out glow-discharging in 
amine and in residual air in separate vacuum recipients: once a device 
is contaminated with an amine, it will remain contaminated with this 
compound. The glow-discharging device that he had built at the EMBL has 
two vacuum recipients, each with its own pump.

Best,
Willem Tichelaar


Eduardo Sanz Garcia wrote:
> The use of alkylamine vapors in glow discharge apparatus makes the
> grid positively charged. But I found some contradictory information
> about the hydrophobicity:
> Some say that it makes the surface hydrophilic, others hydrophobic.
> If it makes the surface hydrophobic, while is still used in cryoEM?
> Shouldn't that prevent the fluid from spreading evenly on the grid
> surface?
> Does someone have experience in this type of treatment?
>
> Additionally,
> Has someone use magnesium acetate, lysine or polylysine after glow
> discharge to make the surface positively charged?
>
> Thank you.
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>   

-- 
Willem Tichelaar, Ph.D.
European Molecular Biology Laboratory
Meyerhofstr. 1
69117 Heidelberg, Germany

phone: +49 (0)6221 387 193; fax: +49 (0)6221 387 519