Synthesis of Stable Magnetic Polyaniline Nanohybrids with Pyrene as a Cross-Linker for Simultaneous Diagnosis by Magnetic Resonance Imaging and Photothermal Therapy

We have developed pyrene-modified magnetic polyaniline nanoparticles (MPANs), a hybridization of MnFe₂O₄ magnetic nanoparticles (MNPs) and polyaniline (PANI) with pyrene as a cross-linker, for diagnosis by simultaneous magnetic resonance (MR) imaging and photothermal therapy. In general, the strong affinity between PANI molecules, owing to interchain hydrogen bonding and the π-π interactions mediated by their aromatic composition, hinders the successful synthesis of complexes of PANI with inorganic materials. To overcome this obstacle, we used pyrene as a cross-linker to synthesize a stable complex of PANI with MNPs. We first modified the hydrophobic MNPs with pyrene through a hydrophobic interaction and then formed a complex with PANI. The pyrene-induced π-π interactions between the pyrene molecules on the MNPs and PANI reduced the affinity between the PANI molecules, and the strong affinity between the PANI molecules and MNPs rendered stable nanocomplexes of MPANs. Finally, Cetuximab-conjugated MPANs were fully tested for simultaneous diagnosis by magnetic resonance imaging (MRI) from superparamagnetic MnFe₂O₄ and photothermal ablation therapy from the near-infrared absorbing characteristics of PANI in epidermal growth factor receptor (EGFR) overexpressed cancer cells (A-431 cells) in vitro.