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. 2021 Oct 15;19:323. doi: 10.1186/s12951-021-01063-4

Fig. 4.

Fig. 4

Characterizations of PDA NPs. a Transmission electron microscopy (TEM) image, scale bar: 100 nm. b Particle size distribution analysis performed with dynamic light scattering (DLS). c Ultraviolet absorption spectrum of siRNA/PEI. d Infrared (FTIR) spectrum of siRNA/PEI@PDA and FA modified siRNA/PEI@PDA