Here, we report the development of probes for magnetic drug delivery. These probes consist of monodisperse superparamagnetic iron oxide nanoparticles (NPs) which cluster upon functionalization if the NP size does not exceed 6-7 nm. This clustering significantly affects drug uptake and release. However, as-synthesized iron oxide NPs are coated with oleic acid and hydrophobic. They need to be functionalized to make them water soluble and biocompatible. For this, we used an amphiphilic multiblock copolymer containing poly(ethylene glycol) and polytetrahydrofuran blocks (PEG<sub>600</sub>PTHF<sub>650</sub>). Upon functionalization, it is observed that 6 nm NPs form clusters, while 12 and 22 nm NPs remain individually dispersed. With these NPs we studied the uptake and release of Rhodamine B base, a hydrophobic molecule which mimics some hydrophobic drugs, and doxorubicin, an anticancer drug. The mechanism used to release the dye/drug is a change of hydrophilicity/hydrophobicity balance which imitates the passage through a cell wall. A dependence on the NP size and clustering was observed where clusters have more efficient uptake and release. Additionally, uptake and release has been found to have a dependence on the presence of a charge in a dye/drug molecule. The formation of clusters with 6 nm NPs allows for the clusters to be magnetically separated which is useful for efficient purification and drug delivery.

Superparamagnetic iron oxide nanoparticle clustering aided by multiblock amphiphilic copolymer increases drug uptake and release

256th National Meeting (2018)

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