2.7 Cell Experiment
The cytotoxicity of RCNs and DOX@RCNs was assessed by MTT assay. MCF-7 cells were inoculated in plated in 96-well plates for 24h at the standard cell culture system. MCF-7 cells were treated with culture medium containing different concentrations (0-200μg/mL) of RCNs (or DOX@RCNs) for 24h. Subsequently, 20μL MTT was added to each well and incubated with the cells for 3h. After that, the liquid in each hole was sucked out and 150μL DMSO was added, then the value of each hole at the optimal absorbance (490nm) was measured and compared using a microplate reader. When evaluating the effect of PTT on cells, the MCF-7 cells were firstly inoculated for 24h, then the RCNs (or DOX@RCNs) was added incubated with irradiation with NIR light (808nm, 2.5W/cm2) for 5 min, and the same method was used for measurement. In addition, in order to intuitively display the cell apoptosis promoted by nanomaterials, the experimental cells after 4 min irradiation were stained by DAPI and fluorescein-dUTP for 20 min, then taken photographs by confocal laser imaging systems.