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

Abstract

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.