Nova nanosem450

A UV/VIS/NIR Spectrophotometer (UV3600; Shimadzu, Japan) was used to acquire the optical absorption spectra (optical density vs. wavelength) of the INDs and the ink alone. The morphological and structural characterization and size of INDs were observed by a scanning electron microscope (SEM, FEI Nova NanoSEM450; USA) and an optical microscope (Olympus CKX41; CANADA). The size distribution and zeta potential of INDs were measured by a Laser Particle Size Analyzer System (Zeta SIZER3000HS; Malvern, USA).

The morphology of Ta@CaAlg microspheres was studied using an inverted microscope (TH4-200, Olympus), a field-emission scanning electron microscope (SEM, Nova NanoSEM 450) and a transmission electron microscope (TEM, JEM-100CX Ⅱ). The average diameter of Ta@CaAlg microspheres were measured and calculated using Image J (National Institutes of Health (NIH), USA) based on more than 200 microspheres from at least five microscope images. Thermal gravimetric analysis (TGA) was conducted on a Pyris1 TGA (PerkinElmer) instrument. Fluorescence microscopy images were observed using a fluorescence microscope (Olympus FV500). The X-ray imaging ability of Ta@CaAlg microspheres was evaluated in vitro with an IVIS Lumina XR system (Caliper Life Sciences, Hopkinton, USA).