I have gold NPs and I am looking for a reliable procedure how to conjugate SH-PEG-NH2 to gold nanoprticles
if you want to attach SH group TO AuNPs, it only need agitation and incubation. Because Au have direct affinity towards SH group
Imran Mahmood Khan Thank you so much. Yes I need to attached SH-PEG-NH2 to gold NPs but the amount of each one, I think is important
Hello Hanieh Montaseri I think this promising article will be useful to you. Read it carefully especially the attached procedure and if you need any further help, let me know. My Regards
Article A facile approach for the reduction of 4‑nitrophenol and deg...
Dear Mohammad Hegazy
Thank you so much for your advice.
I have synthesized 15 nm and 50 nm AuNPs and added different concentrations of SH-PEG-NH2 to a fixed concentration of each AuNPs. Then I centrifuged them to get the pellet. I also centrifuged the supernatant 2 more times and then resuspended the pellet in PBS. Regarding the 15 nm AuNPs, the absorbance decreased too much which I do not know that would be fine. But for 50 nm AuNPs, the color of solution after suspension in PBS turned to purple-grey which I supposed too much agglomeration and UV/Vis also confirmed it. Do you have any advice what I should do?
Thank you.
Hanieh
Dear John Clarkson
I would like to ask whether freeze thaw ligand exchnage can be also applied for AuNPs? It looks more applicable for AuNRs.
Thank you.
Hanieh
Dear Dr. Montaseri,
Based on your descriptions, you have faced with the aggregation of GNPs in the presence of thiolated PEG. I don't recommend the Freeze-thaw approach. I think it's necessary to reduce the concentration of the thiolated compound.
plz see the following paper as an example:
Scholz, F., Rüttinger, L., Heckmann, T., Freund, L., Gad, A. M., Fischer, T., ... & Söffing, H. H. (2020). Carboxyl functionalized gold nanorods for sensitive visual detection of biomolecules. Biosensors and Bioelectronics, 112324.
Dear Dr Tohid Mahmoudi
Thank you so much for your advice. The lowest concentration I used for 50 nm AuNPs is 1ng/ml, which even for this concentration it showed aggregation.
I will try to apply the paper you attached for me.
Dear John Clarkson
Thank you so much for your advice and the papers.
That looks easy and straightforward approach. I will try to perform the freeze thaw and will inform you if it could be successful.
As a rule of thumb:
The less efficiency of capping step the higher agg. of GNPs in PBS.
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