2.2 Characterization
The microstructure and morphology of the prepared samples were observed by transmission electron microscopy (TEM, SU8220, Hitachi, Japan). The surface groups of RCNs and DOX@RCNs were characterized by FT-IR spectrometer (Spectrum 3™, PerkinElmer, America). The absorbance was measured by UV-vis-NIR spectrophotometer (LAMBDA365, PerkinElmer, America). The specific surface area was measured by surface comparator (ASAP2460, Micromeritics, America). The temperature of the solutions was recorded by a thermal imaging camera (FLIR ONE Pro, Wilsonville, OR). Confocal microscopy photos were taken by an Olympus BX51 fluorescence microscope (Olympus, Tokyo, Japan).