Supramolecular-based PEGylated magnetic hybrid vesicles with ultra-high transverse relaxivity

Abstract

Magnetic vesicles have attracted great attention due to their excellent magnetic properties and wide potentials for application in magnetic resonance imaging. In the present study, we designed and synthesized a new kind of supramolecular-based PEGylated magnetic hybrid vesicles (SPMHVs) that works as a T2-weighted MR contrast agent with ultra-high transverse relaxivity up to 641.7mM−1s−1. The construction of SPMHVs was achieved by self-assembly of the newly synthesized supramolecular-based amphiphilic pseudo-block copolymer polyrotaxane-poly (acrylic acid; PR-PAA) and hydrophobic magnetite nanoparticles, followed by cross-linking with organosilica of 3-mercaptopropyltrimethoxysilane (MPTMS) and poly (ethylene glycol; PEG) modification. Interestingly, the morphology of SPMHVs can be tuned between vesicles and micelles by changing the initial Fe3O4 concentrations in the oil phase (or the Fe3O4 loading amount). A sample of SPMHVs-30 nanoparticles obtained with initial magnetite concentration of 3.0mg/ml in the oil phase especially displayed well-defined vesicular morphology, relatively small particle sizes (<100nm) and excellent colloidal stability under biological conditions. More importantly, the in vivo MR imaging testing results demonstrate that the SPMHVs-30 displayed significantly enhanced T2-weighted contrast imaging performance with passive targeting behavior via permeability and retention (EPR) effects, further demonstrating the promising MR imaging potential of these agents.