Water-soluble hydrogel nanoparticles have been synthesized by the incorporation of the stimuli-sensitive monomer of N-isopropylacrylamide (NIPAM) to a catalytic, molecularly imprinted system. The unique properties of pNIPAM copolymerized with cationic and anionic polymers offers a homogenously biocompatible catalytic system with switchable response to pH change. The maximum catalytic efficiency can thus be significantly increased.