Dear Ricky Dua, not a simple addition, dopamine should be reacted with the polymer chains, as a substitute side group. My Regards

As above, you must graft dopamine on the chitosan backbone, simple adding is meaningless. Catechol groups could provide adhesive property, but polydopamine would lose most catechol groups when polymerization. As a result, polydopamine could adhere locally to the site where it polymerized. After polymerization, polydopamine is not adhesive. So you must protect catechol groups from oxidation to ensure the adhesive property of hydrogels, and catechol groups should be linked to polymer backbone with strong interaction like covalent bonds.

Tong Zongrui, do you mean by protecting the hydroxy group of the catechol with the methyl or boc group?

Hi;

The adhesive properties of the PVA/chitosan mixture are highly dependent on the degree of dopamine substitution. Please check the following document:

With my best regards

Tong Zongrui do you have any experience on grafting dopamine to polymers? I have just tried the reaction using EDC/NHS chemistry (as I usually do for tyramine), but bubbling N2 into the solution. However, I experienced issues as the reaction solution turned dark green in dialysis, so I guess it oxidized. Any suggestions?

Kind regards

Dear all, the most common way is to protect the hydroxyles via methylenation ring closure, i.e., methylenedioxy-. My Regards

Try precipitate the product then solve them to purify before dialysis, so as to shorten dialysis time. Then, seal the container (breaker or else) with PE film or parafilm, and exclude the air with nitrogen. Francesca Perin

Thank you for your kind answer! I figured out the grey/green colour came from unreacted dopamine producing polydopamine, which can be prevented by performing dialysis in acidified distilled water.