To accomplish effective cancer imaging and integrated therapy, the multifunctional nanotheranostic Fe3O4-MTX@HBc core-shell nanoparticles (NPs) were designed. A straightforward method was demonstrated for efficient encapsulation of magnetic NPs into the engineered virus-like particles (VLPs) through the affinity of histidine tags for the methotrexate (MTX)-Ni2+ chelate. HBc144-His VLPs shell could protect Fe3O4-MTX NPs from the recognition by the reticuloendothelial system as well as could increase their cellular uptake efficiency. Through our well-designed tactic, the photothermal efficiency of Fe3O4 NPs were obviously improved in vitro and in vivo upon near-infrared (NIR) laser irradiation. Moreover, Magnetic resonance imaging (MRI) results showed that the Fe3O4-MTX@HBc core-shell NPs were reliable T2-type MRI contrast agents for tumor imaging. Hence the Fe3O4-MTX@HBc core-shell NPs may act as a promising theranostic platform for multimodal cancer treatment.

No abstract

The tumor microenvironment typically possesses immunosuppressive properties that hinder the effectiveness of antitumor immune responses, even in the context of immunotherapies. However, it is observed that pathogenic microorganisms can trigger strong immune responses during infection, offering a potential means to counteract the immunosuppressive environment of tumors. In this study, a protein nanocage called CpG@HBc nanocages (NCs) is developed, which mimics the structure of the hepatitis B virus and combines with an immunostimulatory component known as cytosine phosphoguanosine oligonucleotide (CpG). By delivering these immunostimulatory agents, CpG@HBc NCs are able to effectively reverse the suppressive tumor microenvironment, resulting in the inhibition of poorly immunogenic tumors in mice. Through high‐dimensional mass cytometry (CyTOF) analysis, remarkable alterations in immune responses is observed induced by CpG@HBc. Treatment with immunogenic CpG@HBc NCs, along with co‐injection of an OX40 agonist, sensitized colorectal cancer tumors to T cell immune responses, resulting in significant impairment of tumor growth and robust immune activation. Furthermore, CpG@HBc NCs induced long‐term antitumor immunological memory, protecting tumor‐cured mice from tumor rechallenge. Overall, these findings highlight the potential of a virus‐inspired protein nanocage to mimic anti‐viral immunity and offer a unique therapeutic approach for cancer immunotherapy.