Au nanostars@PDA@Fe3O4-based multifunctional nanoprobe for integrated tumor diagnosis and photothermal therapy

• An Au nanostars@PDA@Fe 3 O 4 -based multifunctional nanoprobe was studied for integrated diagnosis and treatment of animal tumors. • The Au nanostars@PDA@Fe 3 O 4 structure has low photothermal conversion threshold and improved photothermal efficiency, which is promising for MRI, FL positioning, and photothermal treatment. • The composite bioprobe has impressive tumor targeting and biocompatibility. • Photothermal ablation of bulky solid tumors in a xenograft mouse model was achieved. A multifunctional nanoprobe (based on Au nanostars@PDA@Fe 3 O 4 ) is developed for tumor targeted imaging and targeted photothermal therapy. Au nanostars and Fe 3 O 4 are connected with polydopamine, and combined with antibody-FITC or antibody-quantum dots for in vitro or in vivo fluorescence labeling (FL), respectively, to form the composite nanoprobe. The shape and lattice structure of Au nanostars and Fe 3 O 4 were confirmed with TEM, HRTEM and XRD experiments. Compared with other Au nanoparticles@Fe 3 O 4 composite probes, the Au nanostars@PDA@Fe 3 O 4 structure has a low photothermal conversion threshold. Compared with the corresponding pure Au nanostars, the photothermal efficiency of the probe has increased by 50%, while maintaining 171% and 32% fluorescence enhancement in vitro and in vivo , respectively. Due to the charge transfer channel, the phonon emission of Au can go on in Fe 3 O 4 via the PDA linking. Under the precise guidance of multimodal imaging, the nanoprobe conducts homogeneous photothermal ablation of bulky solid tumors (~ 400 mm 3 ) in a xenograft mouse model. Animal model magnetic resonance imaging (MRI) results found that the MRI T2 signal intensity of the probe was 65% stronger than that of pure Fe 3 O 4 nanoparticles. These results suggest that this nanoplatform is promising for integrated tumor diagnosis and targeted cancer therapy.