Amphiphilic starlike dextran wrapped superparamagnetic iron oxide nanoparticle clsuters as effective magnetic resonance imaging probes.

Starlike polymers have been widely used in various fields, such as tissue engineering, imaging, gene and drug delivery because of their unique structures and properties. Dextran has long been used as a temporary plasma substitute because of its excellent biocompatibility. In this study, starlike polysaccharide with multiple dextran arms was designed and developed by attaching dextran to a β-cyclodextrin core through click chemistry. Next, starlike dextran was modified with aliphatic chains and these amphiphilic polymers can self-assemble into nanoscale micelles in water, and their critical micelle concentration values (3.7 × 10(-8) M) are much lower comparing to its linear analogs (1.7 × 10(-7) M), resulting in more stable nanostructures in aqueous environment. These micelles can encapsulate multiple superparamagnetic iron oxide nanoparticles and forming clustering particle nanostructures in water, and the resulting nanocomposites have a high T(2) relaxivity of 436.8 Fe mm(-1) s(-1) under a 1.5T clinical magnetic resonance imaging (MRI) scanner. Further, dual functional probes were developed by loading both superparamagnetic iron oxide nanoparticles and small molecule anticancer drug doxorubicin into polymeric micelles. Multidrug-resistant breast cancer cells MCF-7/Adr treated with these probes can be characterized under MRI.