1H NMR, 1H nuclear magnetic resonance; Biodistribution; Caenorhabditis elegans; DAPI, 4ʹ,6-diamidino-2-phenylindole; Deff, effective diffusion coefficient; EDC, N-(3-di-methylaminopropyl)-Nʹ-ethylcarbodiimide; Epithelium; FT-IR, Fourier transform infrared spectroscopy; FUdR, 5-fluoro-2'-deoxyuridine; GIT, gastrointestinal tract; H2DCF-DA, 2,7'-dichlorodihydro fluorescein diacetate; HPLC, high-performance liquid chromatography; I, insulin; IIS, insulin/IGF-1 signaling; Insulin; Lifespan; MSD, mean square displacement; Mucus-permeating; NGM, nematode growth medium; NPs, nanoparticles; Nanoparticles; ORL, orlistat; Oral delivery; PBST, phosphate-buffered saline with triton; PDI, polydispersity index; PEG, poly(ethylene glycol); PPA, PEG-poly(anhydride) conjugate; PPA-NPs, PEG-poly(anhydride)-coated zein nanoparticles; ROS; ROS, reactive oxygen species; SEM, scanning electron microscopy; SOD, superoxide dismutase; THF, tetrahydrofuran; Zein