PLA nanoparticles loaded with thymol to improve its incorporation into gelatine films

Thymol is an active agent with remarkable antimicrobial properties but with low solubility in water and is able to exert a negative effect on the mechanical properties of protein-based films. Furthermore, it is highly volatile and during the drying of the film-forming solution it may be lost through evaporation, a question that has barely been studied. In a previous investigation, the encapsulation of thymol using PLA was optimized, and, in the present study, these PLA nanoparticles are incorporated into gelatine films to assess their effect on the film properties and thymol evaporation during the drying of the film-forming solution. At the thymol concentrations tested, all the free thymol was completely evaporated during the drying of the film-forming solution, while a part of the thymol encapsulated in PLA nanoparticles remained in the gelatine film matrix. The gelatine films with PLA-thymol nanoparticles showed high transparency, a homogeneous microstructure and antimicrobial properties.