[SilicaFig]

Let me preface my question with a sincere thanks for making this protocol available. This synthesis has been on my wish list for quite some time as I can see the open up of my investigation opportunities if I manage to get it done right.

Please can you clarify the apparent  discrepancy which appears in the protocol …

22.5 g (wet mass ~1.2 g dry) of magnetic core particles …
2L of 99% ethanol ….
50 ml of a 25% ammonia solution …
45 ml Tetraethyl orthosilicate (TEOS) under constant stirring and incubate
Add 400 ml of ddH2O …

and this gives a ratio of:
1g of magnetic core particles, 2 ml TEOS, 88 ml of ethanol, 2.22 ml of 25% ammonia solution , 17.7 ml of water
which conflicts with the statement found under heading Modifications:
…. The standard ratio used in the above protocol is : 1g of magnetic core particles, 2 ml TEOS, 20 ml of ethanol, 0.5 ml of 25% ammonia solution , 4 ml of water

???? My calculations give different ratios,  which ones are the correct ones please.

Also is it 22.5 grams of wet magnetic particles or dried?

Many thanks

David

[admin]

Hey David,

My sincere apology for completely having missed your question. Considering how long ago you wrote it, I hope you have successfully silica coated MNPs in the meantime.

Unfortunately I cannot answer your question concerning the odd ratio difference. To be honest looking at the protocol I am as befuddled by this as you are. However, I have forwarded the question to the part of the team who should be able to solve this mystery.

What I can tell you is that the 22.5 grams are wet. This amount is pretty much exactly what I was able to harvest from the full scale MNP protocol.

Best regards

Tim M

 

 

[Phil Oberacker]

Hi David,

you’re completely right! Thanks for pointing out the discrepancy! The correct ratio is the one given in the main protocol, not in the modifications paragraph. We published a more thorough version containing the correct ratios with bio-protocol (https://bio-protocol.org/e3394) and I just formated the protocol on the homepage accordingly. Sorry for the mislead!

As Tim mentioned correctly, the 22.5 g wet mass are wet beads, they are not dried.

I hope your synthesis worked anyway.
Best regards
Phil

[Author]

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