[Joe]

Just saw this paper and wondered what your thoughts would be:

https://pubs.acs.org/doi/pdf/10.1021/acssuschemeng.9b03554

Have you guys considered using water instead of ethanol as the solvent for the stober process?

Thanks!

Joe

[Phil Oberacker]

That’s actually really cool! Thanks for sharing. No, we haven’t tested using water yet, but this is definitely an interesting protocol to test out 😀

[Kiran]

Dear Oberacker

I have question here.

During coating with TEOS, the last step is heating at 80 C for 4 hours or more. When you do this, the liquid get evaporated fully at 3 hours leaving pasty beads in the beaker.

is this normal ? give me your suggestion

[Phil Oberacker]

Dear Kiran,

No, this is actually not supposed to happen and I can’t say we ever encountered this issue. Besides the beads, ammonia, and TEOS, the solution is basically 2.5 litres of 80% EtOH. Such a solution should not be completely evaporated after 4 h at 80 °C. Maybe the temperature was set to high? However, if you add a reflux funnel on top of the setup or close the opening with a cork (do not completely seal it) there should be no significant loss of liquid volume.

Best regards
Phil

 

[Eunhae Koo]

Protocol in the silica coated MNP was channged v1.3 recently.

What results are expected  in the silica coated MNP synthesized by the protocol v1.2 and v1.3?

Eunhae

[Phil Oberacker]

Hi Eunhae,

both protocols will work fine. The main difference is that we add the TEOS later in V1.3. This is to ensure the ammonia is equally distributed and the reaction conditions are perfect before starting it with the addition of TEOS. We see a better yield in coated beads, but if you synthesized with V1.2 that’s fine too. However, for the most thorough protocol I suggest the paper we published on Bioprotocol: https://bio-protocol.org/e3394

Cheers
Phil

[Eunhae Koo]

Hi Phill,

Thank you for your kind response.

I want to get the silca coated MNPs with the spherical shape. However, I got aggregated particles of silica coated MNPs via the protocol v1.2. Would you please let me know what is key factor to get spherical silica coated magnetic beads?

Eunhae

[Phil Oberacker]

Hi Eunhae,

I talked to our synthesis specialist about your issue and he mentioned that the main issue for clustering is a high MNP concentration. So if you do the whole procedure diluted, either by using less MNP wet mass or do it in higher volumes, you should be fine.

Let me know if it worked! 🙂

Cheers
Phil

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