A novel method to in situ synthesis of magnetic poly(N-isopropylacrylamide-co-acrylic acid) nanogels

The monodisperse and magnetic Fe3O4/poly(N-isopropylacrylamide-co-acrylic acid) nanogels (Fe3O4/P(NIPAM-co-AA)) have been synthesized successfully by in situ oxidation. Firstly, N-isopropylacrylamide (NIPAM) and acrylic acid (AA) were used as monomers to synthesize P(NIPAM-co-AA) nanogels by emulsion precipitation polymerization in aqueous solution, followed by in situ oxidation of Fe2+ into Fe3O4 nanocrystals inside the network of the P(NIPAM-co-AA) nanogels. The resulting magnetic nanogels had a very good superparamagnetic property measured with vibrating sample magnetometer (VSM) with magnetization value of 2.7 emu g−1 and sensitive T2-weighted in vitro magnetic resonance imaging (MRI) with r2 relaxivity of approximately 439.23 mM−1 s−1. This work would provide the possibility of using the novel Fe3O4/P(NIPAM-co-AA) nanogels as MRI contrast agent.