Encapsulation of liquid metal nanoparticles inside metal–organic frameworks for hydrogel-integrated dual functional biotherapy

Liquid metals represent emerging functional materials for many applications, yet their chemistries for surface/interface engineering and composite development have remained elusive. Here, we present a nanocomposite material featured by a liquid metal core encapsulated in a zeolitic-imidazolate framework shell. An initial functionalization step of liquid metal nanoparticles with amphiphilic surfactant molecules allows on-demand manipulation of the interparticle assembly between liquid metals and metal–organic frameworks, yielding a supraparticle-like composite material with multilevel surface structure and synergistic multifunctionality. The resulting supraparticles are employed as light-activable nanofillers in an alginate-based hydrogel, which displays good injectability, physiologically responsive sol–gel transformation, stable photothermal performance, and controllable zinc ion release. A temperature increase of 31.0 °C is achieved with the composite hydrogel after laser irradiation for 10 min (808 nm laser, 1.5 W/cm2). The composite hydrogel then serves as safe, biodegradable (65.2 % degradation 14 days post implantation), dual functional antitumor and antibacterial biomedicine in an epidermal tumor model and an abscess model. Tumor cells/bacteria seeded on mice are completely (∼100 %) eradicated after a single treatment with laser-activated composite hydrogel. This study offers a pioneering road map for the design and fabrication of liquid metal/metal–organic framework composites, which is expected to trigger broad innovations in liquid metal nanotechnologies not limited to nano/biomedicine.