(a) Effect of polymer concentration and core percentage on surface PEG brush density of polymeric core-shell NPs formed using FNP. (Reprinted with permission from Ref. [144]. 2018, American Chemical Society.) (b) Two-step FNC process preparing Eudragit-coated insulin-loaded HTCC/TPP nanocomplexes, and TEM images of nanocomplexes prepared by FNC, bulk mixing, or dropwise addition. (Reprinted with permission from Ref. [151]. 2019, American Chemical Society.) (c) Schematic of sequential FNC system for preparation of CPP/insulin NP (NP-A) core, hyaluronic acid-coated NPs (NP-B) and HPMCP-coated NP-B (MC); bottom: corresponding TEM images. (Reprinted with permission from Ref. [29]. 2018, Royal Society of Chemistry.)