Graphene oxide (GO) super thin TEM support films / coated grids
Graphene Oxide (GO range) are super thin (<1nm) naturally hydrophilic support films.
Please note: Pre-treatment of GO support films is not necessary before using. The hydrophilic surface will facilitate the even spread of particle suspensions across the grid. We would actively discourage any form of plasma cleaning or glow discharge as it will damage the support film.
Graphene oxide support films are available on Holey Carbon , Lacey Carbon and Quantifoils R1.2/1.3, R2/2 and R2/4.
If you require GO on other types of support please contact us to discuss your requirements.
Graphene and Graphene Oxide (GO) have been known for some time to offer distinct benefits as thin support films for TEM. Whilst Graphene grown by CVD offers the possibility of a continuous film the methods of production are technically complex and expensive for large scale manufacture of coated TEM grids. Graphene oxide offers a cost effective alternative to Graphene. GO monolayers are typically 50% thinner than the equivalent carbon support film offering an ideal solution for viewing nanoparticles by TEM where a continuous support is necessary. Graphene oxide films are almost transparent under the electron beam and not easily visible under an optical microscope. As part of our quality process we check each batch using TEM imaging and diffraction to characterise the grids.
EM Resolutions can offer coated grids with a varying thicknesses of GO to best suit your application. When deciding which is best for you one needs to consider a compromise between grid coverage vs the number of layers (thickness of GO).
We ensure that the GO covers a given % of holes in the support film using three key metrics:
(1) % of the area of the grid holes covered (coverage)
(2) the average number of GO layers across each hole
(3) what % of the covered holes are monolayer.
For good ‘monolayer’ coverage we would expect ~ 50% coverage, of which the majority is monolayer (i.e. a total of ~ 30% monolayer across the grid area). Depending on your application you need to decide if it is more important to have high coverage or a high monolayer fraction.
For good overall coverage of> 80% coverage we would expect typically 2-3 layers of GO with < 20% as monolayer GO. These films are ideal for carbonaceous particles where carbon supports cannot be used.
EM Resolutions offers GO support films on a range of carefully selected coated grid types. We use holey and lacey support films on hexagonal grids to ensure the most even coverage of GO that is suitable for your application.
GO support films are also available on R2/2 R2/4 and R1.2/1.3 Quantifoils.
The hole at position A has no GO film and thus no Ferritin particles. The hydrophobic nature of an amorphous carbon film is also shown at position B where there is no GO and the Ferritin is irregularly dispersed, tending to clump around the holes in the Lacey carbon.
Position C showns a single layer sheet of GO spanning one of the holes and the effect on the particle distribution. The difference in background contrast between Carbon, GO and no support film can clearly be seen in this area.
The hydrophilic nature and advantages of a GO support film are shown across the film on the left of the image (position D) with the more even distribution of the Ferritin on the thinner GO support film.
TEM image of linearised DNA on a GO support film on Lacey carbon courtesy of Larry Scipioni, ZS Genetics
DNA which is first treated to get it to linearize, readily sticks to an untreated GO support film. It can be difficult to get DNA to stick directly to a carbon film so the ultra thin, hydrophilic nature of a GO support film opens up new possibilities for this, and other applications.
Recently published work using DNA also shows GO support films gaining acceptance for cryoTEM studies.
Marcel W. P. van de Put et al (2015), Graphene oxide single sheets as substrates for high resolution cryoTEM Soft Matter, 2015, 11, 1265–1270