Chitooligosaccharide-europium (III) functional micron complex with visualized inflammation monitoring, immunomodulation and pro-vascularization activities for effective wound healing of pressure ulcers injury

Ischaemia and inflammation can hinder the wound healing process in pressure ulcer (PU) injuries. Direct monitoring of the healing status and multi-stage adaptive repair have not been realised in the PU treatment. This study proposes a method to monitor the status of wound healing, while being able to modulate the inflammation and promote vascularization for effective healing of PU injuries, using a complex of chitooligosaccharides (COS) and europium ions (Eu3+). The COS-Eu complex was prepared via one-pot coordination, and its morphology, structure, physicochemical, and fluorescence properties were studied. The results indicate that the COS-Eu complex not only monitors wound healing through fluorescence changes, but also modulates inflammation and promotes vascularization, which were verified both in vitro and in vivo. Noticeably, the COS-Eu complex could shift M1 macrophages to M2 macrophages, demonstrating anti-inflammatory activity. Furthermore, it played a synergistic role with Eu to promote vascularization and tissue regeneration. This simple construction of COS-Eu complex enabled visual monitoring and multi-stage adaptive wound repair, providing a comprehensive solution for PU injury with integrated treatment and monitoring throughout the healing process. (C) 2021 Elsevier Ltd. All rights reserved.