Theoretical and Experimental Bacterial Adherence on Chitosan Films with Varied Characteristics

This paper highlights the importance of chitosan's intrinsic parameters on its performance as a film. Fungal (FC) and crustacean (CSC) chitosans with similar molecular weight (400 kDa) and different deacetylation degrees (FC DDA = 84.2%; CSC DDA ≈ 75%) were utilized to elaborate eco-friendly and functional chitosan-based films (C-films). The physicochemical properties as well as bioactivities were evaluated. Results showed that DDA was positively correlated with the zeta potential of the film-forming solutions. Furthermore, the FC films showed a decrease in moisture and swelling levels by about 20%, accompanied by a slight drop in qualitative hydrophobicity. On the other hand, the antibacterial activity of FC film was significantly stronger against Gram-negative bacteria compared to CSC film. Additionally, the C-films considerably mitigated the adherence of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, where the percentage of the covered surface ranged from 0.5 to 24%. Conversely, Enterococcus faecalis was more resistant, with percentages of the covered surface higher than 50%. Nonetheless, disintegration in cell structure was noticed regarding the CSC film. Ultimately, the theoretical prediction of cell adherence was highly correlated with experimental results (r = -0.89). These promising results demonstrate that C-films with high DDA are excellent candidates for preventing biofilm formation.