I prepared a dilution of 1ml iron oxide suspension in 9ml of 70% ethanol, sonicated in a bath sonicator for 2 hours. After sonication a drop of sample was placed on a glass slide and dried for 2 hours under UV lamp but agglomeration was observed
Can faulty slide preparation result in agglomeration?
Hi Aleena Haqqi
Prepare in a lesser solvent medium if possible or try to dry in a vacuum oven.
I can suggest this from my point of view. I'll try to add more to this later.
Regards
Aggregation will always be observed as you remove the solvent from the system. I really do not know what you are expecting to observe.
Hi Aleena Haqqi,
Just a general comment: preparation of SEM samples on a glass slide is problematic, as the glass is inherently an insulator. When imaging insulators in the SEM, a phenomenon called charging can occur, which can distort your image in various ways. This is alleviated with low vacuum, coating, operation at low accelerating potentials or a combination of the former. However these techniques have specific tradeoffs, mainly in resolution or image quality.
Agglomeration will occur regardless of preparation method unless you functionalize the nanoparticle surface, typically with a surfactant or change the pH to obtain a colloidal suspension. In these cases, drying typically reverses these methods, hence why nanoparticles are typically seen as agglomerates in SEM and even TEM images (although TEM can have a small field of view to only look at single NPs).
Good luck with this problem!
Dear Aleena, thanks for posting this interesting technical question on RG. In addition to the expert answer provided by Alec Ladonis please also have a look at the following potentially useful guides to SEM analysis of nanoparticles:
Scanning Electron Microscopy Analysis (SEM) of Nanopar ticle Samples
https://www.nanopartikel.info/data/projekte/nanOxiMet/SOP/nanOxiMet_SOP_SEM-Analysis-Nanoparticle-Samples_V1.pdf
and
Good Practice Guide for the Determination of the Size and Size Distribution of Spherical Nanoparticle samples
https://www.npl.co.uk/special-pages/guides/gpg119_nanoparticle
Please find both articles attached as pdf files.
Good luck with your research!
Omar Gonzalez-Ortega I'm hoping for separated Iron oxide nanoparticles in SEM imaging
Aleena Haqqi dilute your sample then up to the point where nanoparticles never come in contact with each other upon drying. Good luck with that.
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