Layer-by-layer deposition of magnetic microgel films on plastic surfaces for the preparation of magnetic resonance visibility enhancing coatings

Magnetic resonance visibility enhancing coatings comprising layer-by-layer assembled multilayer films of magnetic microgels and poly(sodium 4-styrenesulfonate) (PSS) were successfully fabricated on hydrophobic plastic surfaces based on electrostatic interaction as the driving force. The magnetic microgels, which were chemically cross-linked poly(allylamine hydrochloride) (PAH) and dextran (PAH-D) encapsulated with superparamagnetic Fe₃O₄ nanoparticles (NPs) acted as the magnetic resonance imaging (MRI) contrast agents in the multilayer films. The magnetic film deposition is initiated with the deposition of the PAH-D microgels because of their strong affinity toward plastic surfaces and so complicated steps for plastic surface modification are avoided. The as-prepared multilayer films of magnetic microgels are stable and have satisfactory adhesion with the underlying plastic surface. The plastic substrates deposited with multilayer films of magnetic microgels are capable of being clearly visualized in vitro by MRI equipment. The easy fabrication of MR emitting coatings on hydrophobic plastic surfaces combined with the capability of the LbL assembly technique for film deposition on substrates of irregular shapes provides a facile way to deposit magnetic resonance visibility enhancing coatings on plastic intervention tools for their application in MRI-guided therapy.