Selective magnetic particle imaging of CD44 expressing cells using iron oxide nanoprobes functionalized with chemically modified hyaluronan.

Hyaluronan (HA) is a naturally occurring biocompatible and non-immunogenic linear anionic glycosaminoglycan. In an attempt to enhance the selective binding of HA to the cluster of differentiation 44 (CD44), we recently identified a novel chemically modified HA derivative (referred to as G2HA) with improved affinity to CD44 compared to the native HA polymer. In this study, we aimed at conjugating G2HA to iron oxide nanoparticles (IONPs) and assessing the uptake of the G2HA-IONP nanocomposite by CD44 expressing cells, namely 4T1 breast cancer cells. In addition, the utility of G2HA-IONPs as efficient contrast agents for Magnetic Particle Imaging (MPI) was studied. The IONPs were synthesized by the thermal decomposition method, and G2HA was conjugated to the nanoparticles by the ligand exchange method. HA-IONPs were prepared similarly for comparison. The uptake of G2HA-IONPs by 4T1 breast cancer cells was HA-receptor dependent, and higher than that of HA-IONPs at the same iron concentration as validated in multiple assays. The cell viability assay verified that G2HA-IONPs were biocompatible at the highest tested dose. The suitability of G2HA-IONPs as MPI contrast agents was tested. MPI of cells that received the nanoparticles demonstrated that the improved uptake of G2HA-IONPs translated into more intense signals, with a 2.4-fold MPI signal enhancement compared to those from cells that received HA-IONPs. Overall, the findings of this study validated the role of the modified HA derivative (G2HA) in enhancing the uptake of iron oxide nanoparticles and asserted the potential applicability of the developed G2HA-IONPs for selective imaging of CD44-expressing cells and as a potential vehicle for drug delivery.