Hello Everyone,
Im working on the nanomicelles which are soluble in water. I did the particle size analysis of these nanomicelles using laser particle size analyser and the particle size was 5-7 nm. When I did the analysis of the same particles by same way using TEM the particle size was 5-35 nm. Im really not sure why this is happening. Can anyone please explain me why is this happening? which results should I trust.
Thanks
Sachin
Can you elaborate the sample preparation for TEM analysis.
My opinion is, in particle size analyser, the particles were in a suspension, where the concentration of the micellar component and the dispersion medium doesnt change. So they might have been in stable size.
But during TEM sample preparation , the solution containing the micelles would have been drop casted and dried... And might be during this drying process the valume of dispersion medium would be differing from each time point, which would lead to difference in the concentration of the micellar components in the dispersion solution.. this would have lead to formation of larger micelles (coalescence)..
Hello Arun,
I prepared the sample as you predicted. I dont know how to resolve this problem, any suggestions ??
Hello Dr. Phillies,
These micelles made up of ceramide and rubososide ( a sweetener ). Yes, these particles are charged, water soluble and have zeta potential of 30 mV.
OK, how concentrated are they (weight/volume is good)? How much salt is in solution?
Hi Sachin Khiste,
If it was me, the next thing i would try is to dilute the sample a lot and then try examining it... Most of the time, sample concentration for electron microscopic(both SEM and TEM) analysis of nanoparticles are lot tricky.. have to play around a lot to get a good image without these artifacts..
If you have access to AFM , just use it to show the particle size.. not much sample prep is needed..
Good luck..
Hi Sachin, although not quite familiar with TEM, there are a few points I would consider to double check:
1. CMC of the surfactant comparing to the concentration you are using, it maybe even worth to check the concentration below cmc to make sure if you can get 'nothing' from the image (if your surfactant is not too big), if there are still large sized particles, then perhaps the container/base for your samples have some interactions to the surfactants and lead to coalescence.
2. Results from laser particle analyser with higher concentration of surfactant, see if you can get those larger sizes up to 35nm
3. Try to contact the manufacturer of your TEM and see if they can offer any technical support to your circumstances
At 10-20% w/v, you are studying a concentrated solution. Light scattering spectroscopy -- I am assuming you did that, and not elastic neutron scattering -- measures the relaxation of concentration fluctuations (diffusion). It does not measure particle size, except via the claim that you are studying extremely dilute spheres. Your objects are not dilute at all, and are probably not spheres except as an average over large fluctuations. Your diffusion coefficient for the particles is an accurate mutual diffusion coefficient, up to complications that I will skip. The quoted radii are an artifact of the computer software.
Yes, I would not trust non of them.
What you describe is more than unclear. Micelles from ceramides would be only expected if they are short alkyl chain.
http://www.sciencedirect.com/science/article/pii/S0005273606003579
Do not know the molecular structure of the sweetener, however, I would assume that this is highly water soluble, i.e. should be located outside the micelles if there are any.
Maybe situation could be different when there is complexing between ceramide and sweetener.
Why do you name the postulated micelles nanomicelles? Except less common giant micelles micelles are nano by nature.
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