Injectable and Wet-Adhesive Coacervate with Enhanced Photothermal Properties for Localized Tumor Treatment

Photothermal therapy (PTT) has attracted increasing attention in tumor treatment due to its high spatiotemporal selectivity and low systemic toxicity. However, their clinical outcomes are severely limited by the rapid attenuation of the photothermal effect in vivo . Herein, we designed a photothermal coacervate through dual metal coordination interactions among carboxymethyl Poria cocos polysaccharide, tannic acid (TA), and ferric ion (Fe 3+ ). The excellent fluidity, wettability, and wet-adhesive properties of the photothermal coacervate enable its efficient coverage and adhesion to tumor tissues, thereby facilitating the sustained retention at the tumor site. Compared with the TA-Fe 3+ complex, the coacervate exhibits superior photothermal performance due to the denser macromolecular networks induced by coacervation, thereby showing higher inhibition rates against bacteria and tumor cells under near-infrared irradiation. The coacervate shows significant in vivo antitumor efficacy due to its sustained photothermal and cytotoxic effects at the tumor site. This work not only offers valuable insights into the design of functional coacervate-based biomaterials but also proposes a highly efficient PTT strategy for localized tumor treatment.