Rational Design of Branched Au–Fe3O4 Janus Nanoparticles for Simultaneous Trimodal Imaging and Photothermal Therapy of Cancer Cells

Abstract We report a facile and simple hydrogen reduction method to fabricate PEGylated branched gold (Au)–iron oxide (Fe 3 O 4 ) Janus nanoparticles (JNPs). Note that the hydrogen induces the formation of Fe 3 O 4 during the synthesis process. Due to the strong absorption in the near‐infrared range, branched Au–Fe 3 O 4 JNPs showed a significant photothermal effect with a 40 % calculated photothermal transduction efficiency under a laser irradiation of 808 nm in vitro. Owing to their excellent optical and magnetic properties, branched Au–Fe 3 O 4 JNPs were demonstrated to be advantageous agents for triple‐modal magnetic resonance imaging (MRI)/photoacoustic imaging (PAI)/computed tomography (CT) in vitro. Therefore, the synthetic approach could be extended to prepare Au–metallic oxide JNPs for specific applications.