Fig. 2

Characterization of NPs. Size distribution and TEM images of A PN, B PRN and C PGN; scale bars: 100 nm. D ζ potential change of NPs in phosphate-buffered saline (PBS, pH 7.4 and pH 6.5) for 4 h. E Stability of three kinds of NPs in PBS (pH 7.4) at different time points. F Fluorescence resonance energy transfer (FRET) spectra of PGN at different times after incubation with ATG4B. Excitation wavelength: 490 nm. G Fluorescence resonance energy transfer (FRET) spectra of PRN after different times of incubation with ATG4B. Excitation wavelength: 490 nm.