Superparamagnetic Iron Oxide Nanoparticles (SPIONs) were synthesized and coated with pseudopolyrotaxanes (PPRs) and proposed as a novel hybrid nanostructure for medical imaging and drug delivery. PPRs were prepared by addition of α-cyclodextrin rings to functionalized polyethylene glycol (PEG) chain with hydrophobic triazine end-groups. Non-covalent interactions between SPIONs and PPRs led to the assembly of SPIONs@PRs hybrid nanomaterials. Measurements of the (1)H Nuclear Magnetic Resonance (NMR) relaxation times T(1) and T(2) allowed us to determine the NMR dispersion profiles. Comparison between our SPIONs@PRs hybrid nano-compound and the commercial SPION compound, Endorem, showed a higher transverse relaxivity for SPIONs@PRs. In vitro MRI experiments showed that our SPIONs@PRs produces better negative contrast compared to Endorem and can be considered as a novel MRI contrast agent.