EQUIPMENT & ACCESSORIES CATALOG EDITION V GLOW DISCHARGE SYSTEMS


What is... Glow Discharge?


Electric glow discharge is a type of plasma formed by passing a current at 100 V to several kV through a gas at low pressure (i.e. in a vacuum system). The main application of glow discharge in electron microscopy (EM) is to convert naturally hydrophobic ('water-hating') carbon-coated transmission electron microscopy (TEM) support grids into a hydrophilic ('water- loving') condition. Glow discharge treatment with air will make film surfaces negatively charged and hydrophilic and allow the easy spread of aqueous solutions.


Other treatments include:


Hydrophilic-positive treatment in air with magnesium acetate post-treatment to allow nucleic acid adhesion to carbon films.


Hydrophobic-positive treatment with alkylamine for proteins, antibodies and nucleic acids.


Hydrophobic-negative treatment in air for positively charged protein molecules, (e.g. ferritin and cytochrome c).


Glow discharge can also be used for modifying surface, for example, to increase bond strength of polymers.


Glow discharges are sometimes considered to be 'imperfect' plasmas and cannot be used to plasma etch or plasma ash specimens their use mainly being confined to altering surface energies, not the removal of bulk material.


Application: Ferritin Solution


zzzMiniQ GD Glow Discharge System


OVERVIEW


Designed with simplicity in mind, the easy-to-use MiniQ GD allows for surface modification of TEM grids, resulting in the clear imaging of macromolecules.


FEATURES z Simple operation z Small footprint


z Automatic operation with minimal user intervention required


z Detachable chamber with implosion guard allowing for easy cleaning


z Pre-set profiles with single touch operation


Recommended Applications


• Changing wettability of sur- faces, primarily used for TEM grids to improve the spread of particles/molecules on them.


• Could also be used for SEM and AFM imaging when sam- ples are applied onto sub- strate surfaces from liquid.


• Soft cleaning of surfaces. Application: Molecular Sieve Particles


Low concentration of ferritin solution. No molecules caught on the grid surface.


High concentration of ferritin solution. Poor spread resulting in large agglomerates.


High concentration of ferritin solution. Poor spread resulting in light patches.


Molecular sieve particles applied from suspension onto carbon surface without Glow Discharge


High concentration of ferritin solution. Large number of molecules caught on the surface.


6


Low concentration of ferritin solution. Molecules retained on the surface.


Low concentration of ferritin solution. Glow Discharge of the grid allowed correct staining.


Molecular sieve particles applied from suspension onto carbon surface with Glow Discharge.


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