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Additional file 1: Fig. S1. FT-IR spectra of Fe3O4 and Fe3O4-MPS nanoparticles. Fig. S2. TEM images of Fe3O4@PCBMA-SIM nanoparticles (A); SEM images of Fe3O4@PCBMA-SIM nanoparticles (B). Fig. S3. DLS diameters of Fe3O4@PCBMA-SIM nanoparticles dispersed in water, PBS, bovine serum albumin (BSA) and Dulbecco’s Modified Eagle Medium (DMEM). Fig. S4. The degradation property of Fe3O4 nanoparticles dispersed in different concentrations of GSH (0 mM and 10 mM) and pH values (5.0, 6.5 and 7.4). Fig. S5. Cell viability of ferrous sulfate to MDA-MB-231 cells. Fig. S6. Cell viability of ferrous sulfate to MCF-7 cells. Fig. S7. Biodistribution of Fe3O4 and Fe3O4 @PCBMA nanoparticles after 12 h injection. Fig. S8. Biodistribution of Fe3O4 and Fe3O4 @PCBMA nanoparticles after 48 h injection. Fig. S9. TUNEL staining of tumor tissues. Scale bars was 20 μm. Fig. S10. Whole blood panel analysis of nanoparticle-treated mice at 24 h post-injection.

Liren Zhang, Peng Yang, Ranran Guo, Jiaxin Sun, Ruihong Xie, Wuli Yang State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433, People’s Republic of ChinaCorrespondence: Wuli YangState Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433, People’s Republic of ChinaTel +86-021-31242385Email wlyang@fudan.edu.cnBackground: Chemo-photothermal therapy has attracted intensive attention because of its low side effects and better therapeutic efficiency. Although many photothermal agents have been loaded with chemotherapeutic drugs for chemo-photothermal therapy, their applications are limited by complex synthetic protocols and long-term safety. Therefore, there is significant clinical value in the development of a simple system of biocompatible and biodegradable photothermal nanomaterials with high payloads of chemotherapeutic drugs for chemo-photothermal synergistic therapy.Materials and methods: In this study, PEG-modified polydopamine nanoparticles with mesoporous structure (MPDA-PEG) were successfully obtained by an emulsion-induced interface assembly strategy. Subsequently, paclitaxel (PTX) dissolved in acetone was loaded into the mesoporous channels of MPDA-PEG nanoparticles by solution absorption method. A PTX-loaded MPDA-PEG (MPDA-PEG-PTX) nanoplatform for combination of photothermal therapy (PTT) and chemotherapy was developed.Results: The synthesized MPDA-PEG nanoparticles had a great photothermal effect under near-infrared (NIR) laser irradiation and exhibited an enhanced photothermal effect with the increase of particle size. Meanwhile, MPDA-PEG nanoparticles also had a high payload of PTX, and the PTX release could be greatly accelerated by elevated temperature from photothermal effect. In MTT cytotoxicity assay, A549 cells incubated with MPDA-PEG-PTX under NIR laser irradiation (PTT + chemotherapy group) exhibited better therapeutic effect than single chemotherapy (MPDA-PEG-PTX group) and PTT (MPDA-PEG + Laser group). The synergistic therapeutic effect of MPDA-PEG-PTX with NIR laser irradiation in vivo was further investigated under the guidance of photoacoustic imaging (PAI), tumors of nude mice treated with MPDA-PEG-PTX with NIR laser irradiation were completely eliminated with minimal side effect.Conclusion: The MPDA-PEG-PTX nanoplatform is a simple and effective platform which can completely inhibit tumor growth with minimal side effects under NIR irradiation, and it exhibits better therapeutic effect than single chemotherapy and PTT.Keywords: photothermal therapy, polydopamine, mesoporous nanoparticle, chemotherapy, paclitaxel