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Topic: Stubborn citrate-capped nanoparticles don't want to change phases  (Read 4176 times)

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Offline Bublik

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Stubborn citrate-capped nanoparticles don't want to change phases
« on: September 07, 2016, 10:15:12 AM »
Hey guys,

I'm trying to switch the caps of my gold nanoparticles to from an aqueous citrate-capped solution to an organic thiol-capped solution. I've tried various ways to do this, all of which being variations of mixing the Ct-capped nanoparticles with the desired thiol in an organic solvent, with the idea that the thiol has a higher affinity for the gold and will displace the citrate, resulting in the desired thiol-capped hydrophobic nanoparticles in the organic layer. The Ct-capped nanoparticles range in diameters from ~6 to 24nm.

This procedure is described in countless papers and it just doesn't work that easily. Does anybody have any experience/advice/suggestions for this? I've tried using some phase transfer catalysts, different variations of equivalencies and solvents, and still to no avail.

Offline ididnotgettheidiwant

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Re: Stubborn citrate-capped nanoparticles don't want to change phases
« Reply #1 on: March 06, 2018, 10:57:42 AM »
Hi,

Did you solve this problem? I'm having a similar issue and would love to hear how you solved it.

Thanks!

Offline wildfyr

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Re: Stubborn citrate-capped nanoparticles don't want to change phases
« Reply #2 on: March 06, 2018, 12:49:40 PM »
Try heating it up a bit or adding a little weak base.

Offline wildfyr

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Re: Stubborn citrate-capped nanoparticles don't want to change phases
« Reply #3 on: March 06, 2018, 01:49:27 PM »
Ididnot, would you care to share the identity of the thiol?

Offline ididnotgettheidiwant

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Re: Stubborn citrate-capped nanoparticles don't want to change phases
« Reply #4 on: March 06, 2018, 03:29:50 PM »
Mercaptoacetic acid. Thanks for your suggestions!

Offline wildfyr

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Re: Stubborn citrate-capped nanoparticles don't want to change phases
« Reply #5 on: March 06, 2018, 04:57:28 PM »
This paper seems highly relevant https://pubs.acs.org/doi/pdf/10.1021/la504000v. It doesn't just stir in mercaptoacetic acid to the citrate capped NPs.

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