Fig. 4

Morphology of non-periodic micro–nanostructures. a AFM image of polybromostyrene–polystyrene (PS/PBrS) with nanohills 95 nm high [79]. b Pyramid conceptual model. c Nanostructured (polylactic-co-glycolic acid) (PLGA) (feature dimensions ≅ 50–100 nm). Original magnification =  × 250; scale bar = 100 μm