Formation of hydrogels based on chitosan/alginate for the delivery of lysozyme and their antibacterial activity

- Hydrogels based on chitosan/sodium alginate were prepared and characterized.
- The relative activity of the lysozyme released showed a slight decrease.
- The antibacterial activity of hydrogel loaded with lysozyme was improved.
- The death of S. aureus caused by lysozyme hydrogel was due to disruption of the basement membrane.

Novel hydrogels based on chitosan/sodium alginate (CS-ALG) were prepared to deliver and protect lysozyme while eliminating food-borne microorganisms. These hydrogels were characterized according to the zeta potential, optical microscopy, scanning electron microscopy (SEM), UV-visible spectroscopy (UV-vis), fourier transform infrared (FT-IR), and small-angle X-ray scattering (SAXS). The results demonstrated that the resultant hydrogels were negatively charged and spherical in shape. In addition, the maximum swelling ratio was 45.66 ± 7.62 for CS-ALG hydrogels loaded with lysozyme. The relative activity of the released lysozyme was 87.72 ± 3.96%, indicating that CS-ALG hydrogels are promising matrices for enzyme loading and adsorption. Furthermore, a 100% bacterial clearance rate of CS/ALG loaded with lysozyme was observed to correspond to the superposition effect stimulated by CS and lysozyme, which improved the antibacterial activity against E. coli and S. aureus compared to CS/ALG, suggesting its potential use in the food industry as well as other applications.