Construction of conjugated linoleic acid protection and controlled-release system based on thiolated arabinoxylan...

To achieve gastrointestinal stability of conjugated linoleic acid (CLA) and reduce its oxidative degradation, thiolated arabinoxylan (TAX) was synthesized in this study via an amidation reaction with L-cysteine. Subsequently, TAX was conjugated with CLA via an ester bond to form an amphiphilic TAX-C copolymer, which exhibited excellent dilution stability (critical micelle concentration of only 13.64 μg/mL). Furthermore, CLA was re-encapsulated into TAX-C by ultrasonication and solvent evaporation, denoted as TAX@C. Mechanistic studies revealed that the TAX@C micelle formation was driven by hydrophobic interactions, van der Waals forces, π-π stacking, and hydrogen bonding, as confirmed by Raman spectroscopy, fluorescence, and isothermal titration calorimetry. The study further indicated that TAX@C15 micelles were spherical (particle size of 391.85 nm), with CLA embedded in the hydrophobic core and TAX forming the hydrophilic shell. Compared with free CLA and non-thiolated AX@C15 micelles, TAX@C15 micelles significantly elevated the oxidative stability of CLA (peroxide value reduced to 3.28 mmol/kg). In vitro digestion demonstrated that CLA in TAX@C15 followed a non-Fickian diffusion model for sustained release, with a cumulative release of only 12.59% in simulated gastric fluid. On the other hand, rheological analyses suggested that thiolation significantly improved the mucoadhesive properties of the micelles through disulfide bond-mediated interactions with mucin, resulting in enhanced cohesiveness and deformation resistance. These results indicate that TAX@C15 conjugate micelles are an effective platform for the protection, and controlled release of hydrophobic bioactives.