Photocatalytic CO-releasing spray hydrogel for in situ postoperative cancer treatment

The high invasiveness and metastatic potential of breast cancer increase the risk of postoperative recurrence. To address this issue, a composite hydrogel drug delivery system based on sodium alginate (SA) has been developed for the in situ release of carbon monoxide (CO) at the tumor resection site. This system aims to enhance the effectiveness of chemotherapy and improve the clearance of residual tumor cells after surgery, thereby preventing tumor recurrence and metastasis. A gold nanoparticle-modified g-C₃N₄ nanophotocatalyst (C₃N₄/Au) has been designed to convert CO₂ within the tumor into CO under visible light irradiation. The C₃N₄/Au is loaded into an SA hydrogel and applied to the postoperative incision in a spray form. The rapid crosslinking reaction between SA and Ca²⁺ forms a network structure, enabling precise drug delivery. CO is generated in situ in the postoperative tumor tissue under light stimulation and is combined with folic acid (FA) modified doxorubicin (DOX) micelles (FA@DM) to achieve effective synergy between CO therapy and chemotherapy. The composite hydrogel drug delivery system not only increases the concentration of CO within the tumor and reduces systemic toxicity but also enhances the effectiveness of chemotherapy by increasing oxidative stress within tumor cells. It provides a new and safe strategy for efficient and precise postoperative tumor treatment, reducing the risk of tumor recurrence and metastasis.