The study of natural materials inspires sustainable innovations, with biomimetics excelling in surface modification. Polydopamine (PDA) offers a promising approach for modifying cellulose nanocrystals (CNC), enhancing their compatibility with hydrophobic polymers by improving interfacial adhesion. In this work, the modification of CNC with PDA (CNC@PDA) significantly enhanced the compatibility between the nanocargoes and the cellulose acetate (CA) matrix. The CNC@PDA complex formation was suggested through a combination of FTIR analysis, particle size distribution measurements and ζ-potential analysis. However, the exact mechanism behind dopamine polymerization on the surface of CNC remains a subject of ongoing debate among researchers due to its complexity. This study hypothesized the formation of modified CNC through this process. Furthermore, this study provided a satisfactory investigation of the antimicrobial activity of CNC@PDA in response to bacterial strains (E. coli, P. aeruginosa, S. aureus and L. plantarum) in view of the hypothesis of the possible generation of reactive oxygen species (ROS). Additionally, the incorporation of CNC@PDA CA films was analyzed to assess its effect as a mechanical reinforcement agent. The results showed an improvement in mechanical properties, with the 1% CNC@PDA film exhibiting the best balance between tensile strength and flexibility.

Environmental pollution and food safety are both issues of global concern. In this sense, sustainable and antimicrobial nanocomposites based on cellulose/poly (vinyl alcohol) blend incorporated with natamycin and cellulose nanocrystals (CNC) were manufactured and characterized. The developed films were evaluated according to their mechanical and optical properties, and their barrier to oxygen and water vapor permeation. The antimycotic activity was evaluated in vitro against fungi and yeasts. The film’s potential to act as an active packaging for Minas cheese preservation was also assessed. The incorporation of CNC increased the films’ tensile strength; however, it did not influence the barrier properties to water vapor (4.12 × 10⁻⁷ g·cm.m⁻¹·h⁻¹·Pa⁻¹) and oxygen (3.64 × 10⁻¹³ g·cm·m⁻¹·h⁻¹·Pa⁻¹). The incorporation of natamycin, on the other hand, resulted in films that were more opaque (around 24%) and of a yellowish color. The active nanocomposites developed showed antimicrobial effects against all analyzed fungi and yeasts (approximately 35 mm of inhibition zone) and were able to control the growth of S. cerevisiae in cheese, reducing a log cycle until the 12th day of storage. Since they performed well in vitro and on food, it was concluded that the films showed potential to be applied in Minas cheese preservation.