Double-camouflaged tellurium nanoparticles for enhanced photothermal immunotherapy of tumor

The photothermal conversion properties of tellurium (Te) nanoparticles have been extensively investigated, rendering them a promising candidate for tumor photothermal therapy. However, there is still room for improvement in the development of efficient Te-based drug delivery systems. Here, Te nanoparticles are mineralized with bioactive molecules within attenuated Salmonella (S-Te), which are subsequently taken up by macrophages (RAW264.7) to construct a double-camouflaged delivery platform (RS-Te). Remarkably, RS-Te retains superior photothermal properties under near-infrared irradiation. The mineralization process eliminates bacterial proliferation potential, thereby mitigating the risk of excessive bacterial growth in vivo . Furthermore, the uptake of bacteria by macrophages not only polarizes them into M1 macrophages to induce an anti-tumor immune response but also circumvents any adverse effects caused by complex antigens on the bacterial surface. The results show that RS-Te can effectively accumulate and retain in tumors. RS-Te-mediated photothermal immunotherapy largely promotes the maturation of dendritic cells and priming of cytotoxic T cells induced by near-infrared laser irradiation. Moreover, RS-Te can switch the activation of macrophages from an immunosuppressive M2 phenotype to a more inflammatory M1 state. The double-camouflaged delivery system may offer highly efficient and safe cancer treatment.