Relation between structures and functions of gel-like nanoparticles with thermo-responsitiveness

To design nanoparticles of a stimuli-sensitive gel, we prepared a copolymer having both thermo-responsitiveness and reactivity. The copolymers were obtained by solution polymerization with N-isopropylacrylamide and N-methacryloxysuccinimide, and they were allowed to react with cystamine and were reduced to introduce sulfhydryl groups. The obtained polymers were precipitated to form nanoparticles by raising temperature, and then nanoparticles were cross-linked with disulfide bonds. The nanoparticle could be disrupted by the breakage of disulfide bonds when the reducing reagents were added. This behavior was related to the molecular size of reducing agents. Macromolecules like proteins could be incorporated into the particles to a higher degree than small molecules. This is because nanoparticles were gel-like and their cross-linking density was relatively low.