a FT-IR spectra of T HCl (a), Eudragit® RS100 (b), T HCl/Eudragit® RS100 physical mixture (1:1) (c), and freeze-dried F5 NP suspension (d). b FT-IR spectra of T HCl (a), chitosan (b), T HCl/chitosan physical mixture (1:1) (c), and freeze-dried F14 NP suspension (d)