Analysis results of PLN encapsulating drug (i.e., calcein as a model drug): a) collection vials from a size-exclusion gel chromatography column (from left to right collected, flow rate 0.25 mL/min), demonstrating that calcein encapsulated in PLN was well separated from free calcein (0.5 mL of 7,8, and 9 samples from 5 mL sample solution were transferred to demonstrate the effects); b) particle size analysis by DLS, showing a monodisperse particle size distribution; and c) UV/Vis spectra of PLN encapsulating calcein and 99mTc-PLN that are different from free calcein.