Alginate sponge assisted instantize liquid metal nanocomposite for photothermo-chemotherapy

Ga-based liquid metals nanoparticles (LMPs), which exhibit both fluidity and metallicity, together with unique physicochemical properties, are emerging as next-generation functional materials in broad biomedical applications. However, various negative effects accompanying with the storage and utilization of LMPs, including spontaneous coalescence, aggregation and oxidation, insufficient dissolution, as well as instability in aqueous solutions, severely hinder their further clinical translation. Here, we proposed a concept of instantize LMPs composite material based on a spongy structural scaffold encapsulating strategy, and synthesized in-situ cross-linked Ga-alginate microgels (ALGa microgels) loaded composite sponge (ALGa sponge) by a facile sonochemical method. Strikingly, it was found that the fast-dissolving spongy structural scaffolds could not only effectively overcome the instability of oxidizable LMPs for long-term preservation in an air environment at room temperature, but also ensure instant dissolution and colloidal stabilization for convenient and efficient utilization in aqueous solution. Simultaneously, the encapsulated ALGa microgels exhibited complementary advantages of in situ cross-linked microgel shells (enhancing water stability, improving biosafety, and drug loading/stimulus-responsive releasing capacity) and internal LMPs cores (radiopacity cellular internalization, and photothermal effect). Moreover, the in vitro and in vivo studies demonstrated that the developed ALGa sponge could enable synergistic phototherapy/chemotherapy under near-infrared laser irradiation, thereby effectively eliminating cancer cells and significantly inhibiting tumor growth. Overall, this pattern provides the possibility for the convenient preparation of multifunctional instantize LMPs composite material, which exhibits great potential to elevate the overall therapeutic performance of photothermal/chemotherapy.