Hi Mohd, you don't need to make an NHS ester to conjugate COOH groups to NH2 groups.

NHS esters are notoriously unstable.

If you Au surface has a COOH modified surface and you want to couple NH2 groups, just use EDC. The NHS ester step is a useless intermediate step that only reduces the coupling efficiency.

Mohd:

For both NHS and EDC chemistry, may be you should not do the reaction@such high Temp., you should cool done before doing the reaction.

Hi Dr Xiang,

I do plan to cool it down back to room temperature before doing the conjugation reaction. I'm just wondering if the high temperature treatment will damage the NHS functionality. Have you tried this before?

I couldn't find NHS heat stability studies from a quick Google search, so I would appreciate if anyone could direct me to the appropriate resources.

Thank you,

Afiq

Afiq

So the NHS functionality is on the surface?

If so, I will not want to heat up the surface.

NHS ester of carboxylic acid is reactive and unstable to moisture, esp @ higher Temp.

Guobing

Noted, thank you for your answer. I'll find other alternatives to my process.

Thank you!

Afiq