Chitosan, alginate, and carboxymethyl cellulose-based film for a controlled release of indocyanine green for antibiofilm applications

• Polysaccharide films controlling indocyanine green (ICG) aggregation and release • Modulation of polysaccharide porous structure and ICG aggregate formation through dye concentration • ICG-polymer interactions and aggregation state affect film organization and dye release behavior • ICG release combines a time-dependent diffusion and a swelling-diffusion mechanism at higher dye concentrations • ICG-enriched polysaccharide films have enhanced antibiofilm activity against Gram-positive bacteria Biofilms on medical devices and wounds significantly contribute to chronic infections in healthcare, as they are highly resistant and difficult to remove, endangering human life and health. Searching for a suitable system to counteract this issue, here we enriched a chitosan (CS), sodium alginate (SA), and carboxymethylcellulose (CMC) film with the indocyanine green (ICG) dye as an antibiofilm drug delivery system. These films retained their structural integrity, showing a homogenous dye distribution. Modulating the ICG concentration enabled obtaining different aggregates, whose stability and release kinetics were evaluated in a phosphate-buffered saline (PBS) solution. A portion of ICG remains trapped in the polymer matrix as a local reservoir, and its release was concentration-dependent, with lower or higher concentrations promoting the monomeric ICG or the preferred J-type aggregate. Infrared spectroscopy elucidated non-covalent interactions between the dye and polysaccharide matrix. X-ray diffraction revealed that low and high ICG concentrations improved film crystallinity, while an intermediate concentration preserved the amorphous structure. The dye enhanced film stability by reducing solubility and moisture uptake. We also modeled the ICG release, which followed Higuchi’s diffusion-controlled model, with increasing concentrations enhancing aggregate diffusion. Lastly, ICG-enriched films effectively inhibited Staphylococcus aureus biofilm formation, demonstrating their potential as antimicrobial coatings. Polysaccharide-based films containing chitosan (CS), sodium alginate (SA), and carboxymethylcellulose (CMC) were obtained by solvent-casting of aqueous dispersions and subsequently enriched with indocyanine green (ICG) dye as a therapeutic agent by immersion. The effect of ICG on the film structure and properties was explored by using increasing dye concentration. Various micro and macroscopic features of the obtained films were determined, alongside the interactions between polysaccharide and ICG, films’ ability to release it over time, its conformation, and films’ antimicrobial potential.