Structural characterization of glycosylated flaxseed protein and its potential as a nanoparticle delivery system

Flaxseed protein (FP) has attracted considerable interest due to its well-balanced amino acid profile; however, its application as a nanocarrier is hindered by inherently poor functional properties. To overcome this limitation, mannose-grafted FP (M-gFP) was synthesized through the Maillard reaction, and the impact of the glycation extent on its structural conformation and subsequent self-assembly behavior was systematically investigated. The results indicated that M-gFP had good potential for the preparation of nanocarriers. Multi-spectroscopic analyses revealed that mannose grafting reduced the α-helix content and disrupted the internal spatial order of native FP. This structural alteration enhanced molecular flexibility and significantly improved protein solubility, thereby facilitating its self-assembly into highly dispersible nanoparticles (NPs). Notably, M-gFP₁ facilitated favorable structural rearrangement, yielding the most compact NPs (154.17 nm) with enhanced viscoelastic characteristics. This nanoscale architecture achieved high curcumin encapsulation efficiency (83.96%) and loading capacity (1.65%), while exhibiting improved stability across diverse pH, thermal, and ionic environments. Bioaccessibility assays further suggested that M-gFP NPs helped protect the payload during simulated gastric digestion and improved curcumin bioaccessibility in the intestinal phase (41.51%). In summary, self-assembled M-gFP NPs, as delivery carriers for hydrophobic bioactive substances, can broaden the application prospects of flaxseed protein in biotechnological delivery systems.