Silica nanoparticles and magnetic nanoparticles were dispersed in toluene with the aid of probe type sonicator followed by addition of APTES to the mixture in order to introduce the amino groups on the surface of nanoparticles. After 48 hr the nanoparticles as shown in the below picture were separated from the mixture by an external magnet.
How silica nanoparticles can be separated with the external magnet in the below picture?
Below Picture contains: APTES: 0.1 gr - NanoSiO2: 0.1 gr - Nano Fe3O4 : 0.1 gr - solvent is phosphate buffer solution.
The silica nanoparticles are not magnetic and therefore the magnetic field is not act on them. Thus this is not a method to separate them, perhaps if you have only magnetite and silica nanoparticles, acting with the magnetic field on the magnetite you can keep them isolated. But what is clear is that the magnetic field cannot do it directly.
Dear Professor Baldomir
I have prepared this nanoparticles as was decribed above. And surprisingly, the final nanoparticles can be collected with external magnet. I will send you an video about this, tommorow afternoon.
Why all nanoparticles can separate with external magnet?
Dear Mahdi,
Ok, let me to see it, but what is clear is that the magnetism does not affect to the silica directly, only if the magnetic nanoparticles do it in some aspects.
Dear Professor Baldomir
I put the video of the separation nanoparticles with external magnet on youtube. As you'll see in the video all silica and magnetic nanoparicles can be collected with external magne. So I'm confused, how silica nanoparticles was separated from solution like magnetic nanoparticles?
You can download video by below link:
https://youtu.be/kfk8e7DR508
Best Regards
Dear Mahdi,
It is quite interesting. Please, put the magnet in opposition to the gravitational force. That is to say, instead of putting it at the side, could you put it in the upper part?
Dear Professor
I will try it tomorrow morning and will send you video by YouTube.
Believe me or not but another experiment you need to do is to repeat your experiment in the dark. Silica nanoparticles have strong magnetic resonance in visible range, see for example: https://arxiv.org/ftp/arxiv/papers/1205/1205.1610.pdf
Dear Professor Baldomir
First I put the magnet at bottom side of the nanoparticle then It was rotated. When magnet is put in the upper side, nanoparticles don't come down.
Pictures:
https://i.imgsafe.org/4c2a333510.jpg
https://i.imgsafe.org/4c2c61b1a0.jpg
Dear Mahdi,
Thank you very much. Now it is clear that there is a ligand between the magnetic nanoparticles and the silica paraticles. Do you have any method to observe this nanoparticles?
Dear Dr. Nerushev,
Thank you so much for your answer and article. I will study the article and send you the results.
Dear Professor Baldomir and Dr Nerushev
Unfortunately I don't do any characterization to these nanoparticles but I will do it in future weeks.
On more question: In your opinion, can this case be related to the zeta potential of the nanoparticles?
Dear Mahdi,
The zeta potential only measures the ionization and this is only of the possibilities, that I think that here is not the central problem.
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