I'm working on polymer based nanoparticles. They are generally round in shape as evident from SEM results. Last week I got few perfectly 'triangular shaped' particles along with so called polymer nanoparticles. Can anyone identify these particles and provide me some information about them?
Hi, Check if your NP-containing buffer has metal salts. These structures could be crystals, formed after drying of the sample for dry SEM. Also, although hugely dependent on particle size and polymer contrast, you can try to see your NPs in cryogenic TEM or SEM, where crystallization will be reduced. Good luck!
Hi,
this is interesting can you give the scale, then the conditions of this observation (what kind of polymere do you use). Thks
Hi, Check if your NP-containing buffer has metal salts. These structures could be crystals, formed after drying of the sample for dry SEM. Also, although hugely dependent on particle size and polymer contrast, you can try to see your NPs in cryogenic TEM or SEM, where crystallization will be reduced. Good luck!
Hi! You can determine the chemical composition of particle by EDAX technique.
Seen even ethylene form bits like these under an SEM in CVD of Graphene before forming into graphene terraces. Fascinating. What is the composition?
Silver & gold are common nanoparticles that can be synthesized as triangles. But I agree with Constantin above, you will need further analysis to confirm their composition. Best of luck!
EDAX will not work as it has limitations of CHON analysis.
This shape might have due to re-crystallization.
It hit my mind when some of you people said 'gold'. Yes, the nanoparticles are sputtered with gold. It may be gold particles then! But, the length of these particles are around 200 nm; is it so large? i doubt!
You can also use XPS. New instruments have lateral resolution of submicron. They should be able to run spectra on your particle and outside. If it is gold it will be very easy to identify. But even if it is polymer, XPS could give precious informations both through the photoelectron C 1s and O 1s regions, the C KLL and O KLL Auger lines, and also through the valence region. Good luck!
Gold has a high mobility and can (especially at elevated temperatures) easily form such large triangular nanoclusters.
I agree with Emil. To me it quite sure these are crystals of some metal salts from the buffer solution.
It seems like metalic particles, but you could perform CBED or micro-beam electron diffraction to evident it.
Are these particles a common phenomena in your SEM picture? They looks like some kind of crystal.
Agree with the crystals of salts. But it should be further characterized. If it can be purified from your polymer particle, many ways are useful for the characterization. If can't be purified, you can perform an EDS on TEM instrument.
In my opinion these particles are gold nanoparticles that results from the gold electrodeposition into the spaces of the PLGA particles. Perhaps what you have carried out is a template based synthesis (top-down strategy). If you have a two dimensional close-packed arrays of polymer nanospheres onto a flat substrate and gold is vapor deposited into the pyramidal voids formed at their intersections, you would obtaind the nanostructures of the image (this would be similar to a nanosphere lithography used by Huang et al in J Phys Chem B, 2005, 109, 18881
Did you perform EDS on them? That should provide you with a shortlist of possibilities at least. Going higher in magnification should also help you observe any morphological propoerties which may be useful in classifying the particles together with their compositional information.
I use gold sputtering at my lab. Gold particles would immediately let you know of their makeup with EDS. So in my opinion you should try it out.
I would first check the composition of the spurious particles; they likely have nothing to do with your polymeric material...
I would carry out EDS experiments first, in order to get information about those nanoparticles.
Going for EDS is advisable and it may also be due to the drying of salt crystals so try XRF as XRF can be done with liquid sample.
EDX will give you the clue to find out what it is. Moreover analyze your starting materials, if it has some metal salts.
You may also repeat washing step of particle production step, so possibility of salt or crystal deposition decreases. Afterwards you can check by SEM again. Metal particles are also possible, we had a similar case while characterizing a material, there were some particles we could not determine and in the we found out that they were metal particle generated from the construction job/metal saw across the lab building. Strict environmental control (maybe working in a hood at dehydration or solvent evaporation step) may solve the problem.
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