In situ synthesis of magnetic poly(N-tert-butyl acrylamide-co-acrylic acid)/Fe3O4 nanogels for magnetic resonance imaging

Abstract

Poly(N-tert-butylacrylamide-co-acrylic acid)/Fe₃O₄ (P(TBA-co-AA)/Fe₃O₄) nanogels have been synthesized successfully by two steps: firstly, poly(N-tert-butylacrylamide-co-acrylic acid) (P(TBA-co-AA)) nanogels were synthesized through emulsion precipitation polymerization by using N-tert-butylacrylamide (TBA) and acrylic acid (AA) as reactive monomers; then P(TBA-co-AA)/Fe₃O₄ nanogels were synthesized by in situ oxidation of Fe²⁺ into Fe₃O₄ nanoparticles inside the networks of the P(TBA-co-AA) nanogels. The prepared P(TBA-co-AA)/Fe₃O₄ nanogels were about 70 nm in dry state, and 118.9 nm in aqueous solution with a low polydispersity index (PDI) of 0.124. The small size and low PDI of the magnetic nanogels could be applied in living body. Besides, the nanogels had good superparamagnetic property, and high r₂ relaxivity value of about 512.01 mM⁻¹ s⁻¹. These magnetic properties endowed the nanogels with a new ability to be applied in T₂-style imaging. In short, this work would provide the possibility of using the P(TBA-co-AA)/Fe₃O₄ nanogels as contrast agents for high resolution of magnetic resonance imaging (MRI).