Fig. 3
![Fig. 3](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12951-018-0401-y/MediaObjects/12951_2018_401_Fig3_HTML.png)
Morphology of mRNA-loaded LPNs (a1, a2) and CS-PLGA NPs (b1, b2) visualized using SEM and TEM. a1, b1 SEM images show a smooth, spherical morphology of the mRNA-loaded nanoparticles and a2, b2 TEM images show the core–shell structure of the particles after staining with 0.5% (w/V) PTA