Antibacterial, ROS scavenging and angiogenesis promoting -Polylysine/gelatin based hydrogel containing CTLP to regulate macrophages for pressure ulcer healing

Pressure ulcers (PUs) have emerged as a substantial burden on individuals and society. The introduction of innovative dressings that facilitate the healing of pressure ulcer wounds represents a cost-effective alternative for treatment. In this study, the emphasis is on the preparation of Carthamus tinctorius L. polysaccharide (CTLP) as hydrogel microspheres (MPs), which are then encapsulated within a hydrogel matrix crosslinked with phenylboronic acid gelatin (Gelatin-PBA) and epsilon-polylysine-grafted catechol (epsilon-PL-Cat) to enable sustained release for promoting pressure ulcer healing. The presented Gelatin-PBA/epsilon-PL-Cat (GPL)/CTLP-MPs hydrogel demonstrated outstanding self-healing properties. In addition, in vitro experiments revealed that the hydrogel exhibited remarkable antibacterial activity, excellent biocompatibility. And it showed the capacity to promote vascular formation, effectively scavenge reactive oxygen species, and facilitate macrophage polarization from the M1 to M2 phenotype. In vivo wound healing of mice PUs indicated that the prepared GPL/CTLP-MPs hydrogel effectively accelerated the formation of granulation tissue and facilitated the healing of the wounds. In summary, in vivo and in vitro experiments consistently highlight the therapeutic potential of GPL/CTLP-MPs hydrogel in facilitating the healing process of PUs.