A facile strategy to fabricate gold nanorod@polyacrylic acid/calcium phosphate（Au NR@-PAA/Ca P） yolk–shell nanoparticles（NPs） composed with a PAA/Ca P shell and an Au NR yolk is reported. The asobtained Au NR@PAA/Ca P yolk–shell NPs possess ultrahigh doxorubicin（DOX） loading capability（1 mg DOX/mg NPs）, superior photothermal conversion property（26%）and p H/near-infrared（NIR） dual-responsive drug delivery performance. The released DOX continuously increased due to the damage of the Ca P shell at low p H values. When the DOX-loaded Au NR@PAA/Ca P yolk–shell NPs wereexposed to NIR irradiation, a burst-like drug release occurs owing to the heat produced by the Au NRs. Furthermore,Au NR@PAA/Ca P yolk–shell NPs are successfully employed for synergic dual-mode X-ray computed tomography/photoacoustic imaging and chemo-photothermal cancer therapy. Therefore, this work brings new insights for the synthesis of multifunctional nanomaterials and extends theranostic applications.

We report a facile and simple hydrogen reduction method to fabricate PEGylated branched gold (Au)-iron oxide (Fe3O4) Janus nanoparticles (JNPs). Note that the hydrogen induces the formation of Fe3O4 during the synthesis process. Due to the strong absorption in the near-infrared range, branched Au-Fe3O4 JNPs showed a significant photothermal effect with a 40% calculated photothermal transduction efficiency under a laser irradiation of 808nm in vitro. Owing to their excellent optical and magnetic properties, branched Au-Fe3O4 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.