Antimicrobial hydrogels composed of chitosan and sulfated polysaccharides of red microalgae

Hydrogels can serve as antimicrobial wound-dressing materials: they act as a physical barrier to bacterial penetration and maintain a moist environment, with improved biocompatibility and mechanical properties. In this research, hydrogels were developed using sulfated polysaccharides from three red microalgae (sea, brackish or fresh water) combined with chitosan (PS_{sea/brackish/fresh}-Chi hydrogels). We have chosen the PS_sea-Chi hydrogels for further studies since they were the stiffest and stable under physiological conditions. Zinc was added to the hydrogels to increase antimicrobial activity. Rheological characterizations of Zn-PS-hydrogels indicated that the stiffness and swelling of the hydrogels decreased with increasing zinc concentration, resulting from the charge-screening effects. SEM analysis showed that Zn-PS-Chi hydrogels were highly porous and zinc-release measurements suggested that all hydrogels shared similar release profiles. Agar diffusion tests suggested that the Zn-PS-Chi hydrogels exhibited a broad-spectrum of antimicrobial activities. The presented characteristics of the Zn-PS-Chi hydrogels highlight their potential use as wound dressings.