Molecular interaction of cyclodextrins with cellulose nanocrystals: A new venue for improving the functional properties of Pickering emulsions

The design of functional delivery systems is essential for storing and releasing active components. Inspired by the structure of Nepenthes mirabilis, cellulose nanocrystals (CNC) cooperate with cyclic alpha-cyclodextrins (alpha-CD), beta-cyclodextrins (beta-CD), and gamma-cyclodextrins (gamma-CD) to form nanocomposites at different mass ratios for the delivery the Mosla chinensis essential oils (EO)-loaded Pickering emulsions (PE), respectively. Characterization methods including FT-IR, TG, XPS, AFM, XRD, and three-phase contact angle were used to analyze the structure of the nanocomposites. The molecular docking and molecular dynamic simulation results revealed that the most hydrogen bonds were formed between beta-CD and CNC, but the tendency for gamma-CD and CNC to bond with hydrogen bonds was stronger in the molecular dynamic simulation. Subsequently, the physicochemical properties of emulsions stabilized by CNC/CDs nanocomposites were characterized through particle size, potential, microstructure, long-term stability, rheology, and aqueous phase distribution indexes. The results showed that the different mass ratios CNC/alpha-CD and CNC/beta-CD nanocomposites stabilized PE had smaller droplet scales and better stability. While CNC/gamma-CD nanocomposites had a negative effect on the emulsion. The in vitro release results showed that the emulsions stabilized by CNC/CDs nanocomposites had a slow-release rate for EO by diffusion. The simulated gastrointestinal release showed that CNC/beta-CD-PE had the highest bioavailability. Moreover, CNC/beta-CD-PE reduced the minimal inhibitory concentration of EO by a mechanism that disrupts the membrane structure of bacteria. Therefore, the introduction of beta-CD may be an effective alternative in regulating the physical properties, function, and stabilization of CNC-based PE. These findings provide a scientific basis for the rational structural design of delivery systems for the encapsulated aroma molecules.