was performed using a JEM-2100F electron microscope at a working voltage
of 200 kV. A UV-3101PC Shimadzu spectrometer was used to measure the
UV–vis spectra. A Zetasizer Nanoseries instrument (Nano ZS90)
was used to measure the zeta potential and size distribution. An FV
1000 camera (Olympus) was used to collect CLSM images. An ultrasonic
transducer (Chattanooga Co., USA) was used in all experiments. A Bruker
EMX electron paramagnetic resonance system was used for the ESR.