Multi-spectroscopy and coarse-grained model reveal self-assembly mechanisms of glycosylated flaxseed protein-ethyl cellulose nanoparticles to enhance curcumin bioaccessibility.

Flaxseed protein (FP) has great potential as a food-grade nanocarrier for bioactive compounds. However, its insufficient stability severely limits its practical application in food systems. To address this limitation, FP was glycosylated (gFP) and complexed with ethyl cellulose (EC) to construct composite nanoparticles (gFP-ECNP). Multi-spectroscopic analyses suggested that EC altered the local tertiary microenvironment of gFP and induced modest conformational adjustments, resulting in reduced particle size and improved dispersibility; gFP-EC0.5NP (prepared with 0.5% (w/v) EC) had the smallest size (111.37 nm). Interaction-force measurements suggested that hydrophobic interactions were the dominant driving force for establishing a compact, stable architecture. Coarse-grained molecular dynamics simulations qualitatively visualized the intermolecular association and co-aggregation of gFP and EC during nanoparticle formation. Additionally, gFP-ECNP maintained good colloidal stability across varied pH, temperature, and NaCl. Upon curcumin (Cur) loading, Cur-gFP-EC0.5NP maintained a relatively small particle size (136.77 nm), achieved a high encapsulation efficiency of 93.75%, exhibited delayed Cur release during simulated gastrointestinal digestion, and showed improved Cur retention under UV irradiation and during storage, while achieving a simulated gastrointestinal bioaccessibility of 52.43%. Overall, this study provides mechanistic insight and practical guidance for the design of stable protein-based nanocarriers for hydrophobic bioactives.