“…Their particle sizes are generally within the range of 10–100 nm, which can improve the physicochemical properties and enhance the solubility and permeability of drugs [ 2 , 3 ]. Compared with traditional oral administration, nanoparticle delivery systems have unique advantages [ 4 ]: (1) they improve the stability and solubility of the drug in the gastrointestinal tract [ 5 , 6 , 7 ]; (2) they promote the penetration and adhesion of the drug in the mucus layer of the gastrointestinal tract, which is beneficial for the drug to reach intestinal epithelial cells [ 8 , 9 , 10 , 11 ]; (3) the controllable release of the drug can be achieved to maintain a stable blood drug concentration [ 12 , 13 ]; (4) by carrying out the surface modification of the nanoparticles, the drug can be targeted for delivery and can be released at the treatment site [ 14 , 15 ]; (5) they can change the absorption mechanism of the gastrointestinal tract and promote drug absorption [ 16 , 17 , 18 ].…”