EQUIPMENT & ACCESSORIES CATALOG EDITION V GLOW DISCHARGE SYSTEMS zzzMiniQ GD (continued) Hydrophobic Surface Why do we need to glow


discharge TEM grids? 1. Remove contaminants


Even freshly prepared carbon layers for TEM grids will have unwanted adsorbates like water and low molecular weight material (LMWM) on the surface, typically adsorbed from the air (Figure 3). These contaminants need to be removed by a glow discharge before using the grids to ensure optimal sample spreading.


2. Improve hydrophilicity and enhance sample adhesion


The deposited carbon layer on the TEM grid has a variably charged surface that is usually hydrophobic, thus even spreading of water- based sample suspensions is difficult (Figure 4). Glow discharge can be used to increase the hydrophilic nature of TEM grids to aid sample adhesion.


3. Improve sample contrast


Observation of biomolecules in ambient TEM conditions also involves staining the sample with heavy metals. TEM supports that have not been treated with a glow discharge will result in uneven staining and cause poor contrast in the image.


4. Prepare grids for cryo-TEM


Carbon surface before Glow Discharge. ca = 66.55˚


DDT modified Au surface before Glow Discharge. ca = 104.24˚


Hydrophilic Surface


Glow discharge of TEM prior to vitrification in cryo-TEM is an essential step. Not only will glow discharge reduce contamination and


promote uniform sample spreading as mentioned previously, it also helps to promote thin vitrified ice formation and prevent particle clumping.3


5. Orient molecules to reveal areas of interest


Chemical vapors can be used to tailor the TEM grid surface and influence the orientation of molecules on the surface. For example, alkylamines such as amylamine or hexylamine, can be used to functionalize the carbon support with amine-containing groups.


These positively charged amine groups will attract negatively charged areas of the sample, and result in a preferential orientation.


Other examples include the use of ammonia to create hydrophilic and mildly basic surfaces, and the use of organic thiols to introduce sulfhydryl groups to the grid’s surface.


Specifications Instrument Dimensions


Carbon surface after Glow Discharge. ca = ~0˚


DDT modified Au surface after Glow Discharge. ca = 20.62˚


Weight Pump


Compliance Safety


Ordering Information Cat No.


Description MiniQGD MiniQ GD Glow Discharge System


225mm W x 325mm H x 420mm D (Total Height with coating head open 480mm H) 8.7kg


You can purchase the instrument with or without a pump.


The MiniQ GD complies to LVD, EMC, RoHS directives. The MiniQ GD conforms to UKCA and European CE industry marks


Vacuum interlocks remove power from deposition sources to prevent users being exposed to high voltage


Qty. each


7


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