Fig. 3
a Temperature changes and b photothermal images of PGNSs, DM1-mPEG-PGNSs and DM1-mPEG/HER-PGNSs after NIR irradiation for 10 min; c Temperature change of PGNS in aqueous solution with a 808 nm laser (3 W cm−2), the irradiation lasted for 500 s then was shut off; d Plot of the cooling time versus –ln(θ) obtained from the cooling stage in c; e temperature increments of PGNSs, DM1-mPEG-PGNSs and DM1-mPEG/HER-PGNSs after nine repeated irradiations (black arrows indicate temperature before illumination and red arrow indicates temperature after illumination); f in vitro release of DM1 of free DM1, DM1-mPEG-PGNSs and DM1-mPEG/HER-PGNSs in phosphate-buffered saline 7.4 at 37 °C; g SK-BR-3 cell viability when exposed to PGNSs, DM1-mPEG-PGNSs, DM1-mPEG/HER-PGNSs and DM1-mPEG/HER-PGNSs + NIR after 24 h; h Different apoptosis cell counts after treating with different DM1 formulations; and i Western blot analysis of HSP70 in SK-BR-3 cells. (**p < 0.01, ***p < 0.001)