Preparation and characterization of a novel antibacterial hydrogel based on thiolated ovalbumin/gelatin with silver ions

Hydrogels synthesized from natural proteins have better biocompatibility than polymer hydrogels. In this paper, the hydrogels (referred to as tOVA/tGel@Ag) was developed using coordinative crosslinking of thiolated ovalbumin (tOVA) and thiolated gelatin (tGel) with silver nitrate. After thiolation with Traut's reagent, the free sulfhydryl group content of ovalbumin increased from 1.5 mu mol/g to 68.6 mu mol/g, and the molecular weight (MW) increased from 44.5 kDa to around 50 kDa. Then, the physicochemical and rheological properties of hydrogels with different tOVA/tGel ratios (10:0, 7:3, 5:5, 3:7, and 0:10) were analyzed. With the decrease in the proportion of tOVA/tGel, the scanning electron microscope (SEM) showed that the network structure of hydrogel became more uniform and denser. Meanwhile, microrheological analysis displayed that the gel properties had been improved, which coincidently confirmed a better water-holding performance. During the antibacterial experiment, the diameter of the bacteriostatic ring of tOVA/tGel@Ag hydrogels against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) could reach 10.8 mm and 10.3 mm respectively, indicating their significant antibacterial properties. In summary, hydrogel prepared with thiolated proteins exhibited a good threedimensional (3D) network structure with the help of silver ions, which was expected to play an important role in the field of food and medicine as antibacterial materials.