Development of self-healing gelatin films based on polyethyleneimine with SiO₂ nanoparticles as functional fillers for active/smart food packaging

Given the growing demand for sustainable and smart packaging, the development of self-healing materials offers a promising strategy to enhance the durability and functionality of food packaging systems. In this study, a self-healing gelatin-based film was developed using polyethyleneimine (PEI) as the primary self-healing agent, while SiO₂ nanoparticles were incorporated as functional fillers to improve mechanical, barrier, and antioxidant properties. Initially, SiO₂ nanoparticles were coated with PEI (forming PEI/SiO₂NP) and then incorporated into a gelatin (GEL) solution to prepare the films (Gel/PEI/SiO₂NP). Fourier transform infrared spectroscopy (FTIR) analysis revealed an increase in the intensity of the NH, OH, and CN vibrations in the amide III band of the healed Gel/PEI/SiO₂NP film, indicating their key role in the self-healing process. Field emission scanning electron microscopy (FE-SEM) confirmed that PEI effectively promotes self-healing properties in the gelatin film. The antioxidant properties, assessed through the DPPH free radical scavenging method, demonstrated that the incorporation of SiO₂ nanoparticles significantly enhances the antioxidant capacity of the films. The addition of PEI and PEI/SiO₂NP increased the swelling ratio while reducing water vapor permeability, thickness, moisture content, and shrinkage. Mechanical analysis showed that the incorporation of PEI and PEI/SiO₂NP significantly improved tensile strength and elongation at break. Overall, the resulting film is suitable for packaging food products prone to physical damage, as its self-healing ability helps prevent further deterioration. Additionally, its strong antioxidant and antibacterial properties make it a promising candidate for active food packaging applications.