Cruciferin coating improves the stability of chitosan nanoparticles at low pH

Encapsulation is an emerging technique to improve the solubility, permeability and bioavailability of bioactive compounds. Cruciferin, a major canola protein, has the potential to protect chitosan-based delivery systems under the gastric conditions due to its resistance to gastric digestion. Positively charged spherical nanoparticles with an average size of 165 nm were prepared. Two water-soluble and -insoluble model compounds (brilliant blue and β-carotene) were encapsulated. The characteristic studies of the particles showed that the chitosan-based core was coated by a cruciferin layer mainly through hydrogen bonding based on FTIR, DSC, surface hydrophobicity, dissociating and intrinsic fluorescence studies. The particles did not show toxicity to Caco-2 cells and their cellular uptake was observed using confocal microscopy. Release studies showed that the particles were resistant to simulated gastric and intestinal fluids and released less than 20% of the encapsulated compounds. Our results suggested that the particles are promising carriers for encapsulation of heat, pH and protease-degradable hydrophilic and hydrophobic bioactive compounds.