Scheme 1. The schematic diagram briefly illuminates the preparation of ICG-Dox/DNA@CaP nanocomposites and the delivery, and release mechanism of loaded therapeutic agents.

Fig. 1. Physicochemical characteristics of CaP nanocomposites. (a) Representative TEM images of CaP nanocomposites, scale bar = 20 nm; (b) Hydrodynamic size and ζ-potential of all CaP nanocomposites; (c) The loading ratio percentage of Dox to DNA, and the loading efficiency of Dox/DNA complexes in CaP; (d) Fluorescence and (e) absorbance spectrum of CaP composites and their components, where the equivalent Dox and ICG concentration was 2 and 10 μg/ml, respectively; (f) Photothermal profile of CaP nanocomposites and free ICG at the equivalent concentration of 10 μg/ml under 808 nm laser irradiation (5 min, 1.5 W/cm2).

Fig. 2. Release characteristics of Dox/DNA complexes. Dox release profile from Dox/DNA complexes at 37 °C (a) in pH 5.0 and 7.4 buffers; (b) in the presence of DNase I; (c) in DMEM, DMEM containing 10 % FBS, MCF-7 cell lysate and the HEPES buffer used for cell lysate preparation.

Fig. 3. Release characteristics of DNA, ICG and Dox from CaP nanocomposites. (a) DNA and (b) ICG release profile from CaP nanocomposites in pH 6.0 and 7.4 buffers at 37 °C; (c) Dox release profile from CaP nanocomposites incubated in HAc-NaAc buffer containing DNase I (pH 6.0) and DMEM containing 10 % FBS (pH 7.4) at 37 °C.

Fig. 4. Flow cytometry analysis of MCF-7 cells incubated with Cy5-DNA@CaP nanocomposites. (a) Time-dependent cellular uptake at 50 nM of Cy5-DNA; (b) Dose-dependent cellular uptake for 4 h.

Fig. 5. Confocal images about uptake of ICG-Dox/DNA@CaP nanocomposites by MCF-7 cells.

Fig. 6. Cytotoxicity of CaP nanocomposites in single and combined modes on MCF-7 cells. (a) Cell viability of MCF-7 cells after treatment with free Dox, Dox/DNA complexes, and Dox/DNA@CaP nanocomposites, (b) without and (c) with 808 nm laser irradiation (5 min, 1.5 W/cm2). D, I and I + D represents Dox@CaP, ICG@CaP, and ICG-Dox/DNA@CaP, respectively.