I have prepared water in oil in water double nanoemulsions samples .The formulation consist of sample extract 25mg + 4% oil + 2% Tween20 + 1% Chitosan(90% deacetylated). DLS results show Mean average size of 128 nm with PDI 0.299. For FESEM I have diluted the sample 25 & 50 times to the conc. of sample extract, and 10 uL solution dropped on glass slide covered with aluminium foil kept overnight to dry the drop. After that SEM imaging done & very few particles observed & aggregates particles also found.
Can anyone kindly suggest how to fix nanoemulsion sample on glass slide to get an SEM picture.
hello,
The best is to do cryo-SEM. You fast freeze a droplet then you fracture it before observation. So like that you keep your emulsion structure.
By drying your droplet, you loose your emulsion structure. material mostly aggregates at the rim of the droplet.
Nicolas Barois is right : cryo SEM would be the preferred way to look at your emulsions (this is how ice cream manufacturers work).
I may also suggest using WetSem capsules, if it works with your sample : see for instance https://www.emsdiasum.com/microscopy/products/sem/wetsem.aspx
I used to work with those to image dispersions, not emulsions, so I don't know if this would work for you, especially at your requried scale.
I agree that freeze-fracture technique is the best for you specimen, but if you have no access to a Cryo-SEM you are out of luck. The second best -WetSem capsules, but you need high accelerating voltages and BSE imaging, so it can be problematic on nanoscale. D
Air drying your emulsion will completely destroy its structure but you still can observe particles, and it looks like you did it. Of course most particles will be in aggregates. If particles are of the most interest, I think you can just observe chitosan powder.
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