I have nanoparticles with amino group and I want to cover it with Biotin. I found some papers and all of them say that before the reaction they ahve to modify Biotin with NHS. I wanna know the exact reason for that as i guess its possible to perform a direct reaction between Biotin and primary amine to form amide.
Dear Alexey Tarabarov ,
Carboxylic acids are poor electrophils, so the direct reaction with primary amines to yield amides is highly inefficient. Transforming the COOH group into a more reactive species solves this issue.
This is the purpose of NHS. Usually, you start by reacting the COOH-containing molecule with a diimide (such as DCC or EDC), and the resulting product is mixed with NHS. The final product is an active ester more susceptible to nucleophilic attacks. See the image attached.
Hope you find it helpful.
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