How to activate polystyrene with carboxyl group? Is there a simple (that is one that requires few and not very exotic reagents) chemical reaction to &quot;activate&quot; or &quot;functionalize&quot; the polystyrene of a simple microtitre plate?
In other words, I would like to add carboxyl groups to the surface of a common ELISA plate to then use ethyl-carbodiimide hydrochloride and N-hydroxysuccinimide to immobilize a target on the bottom of the well.
It is certainly possible to nitrate polystyrene powder with nitric &amp; sulfuric acid mixture and reduce the nitro groups to aniline with $\ce{SnCl2/HCl}$ as described in here1. How effective this would be for a microtitre plate I cannot say, but chemistry is an experimental subject.
Reference

Zhao, H. &amp; Guo, J. &amp; Bian, L. &amp; Wei, Z. &amp; Deng, K.. (2009). Synthesis of nitro and amino linear polystyrene. Hecheng Shuzhi Ji Suliao/China Synthetic Resin and Plastics. 26. 22-26. (link)