Search

Ultra‐high field (UHF) magnetic resonance imaging (MRI) has emerged as a focal point of interest in the field of cancer diagnosis. Despite the ability of current paramagnetic or superparamagnetic smart MRI contrast agents to selectively enhance tumor signals in low‐field MRI, their effectiveness at UHF remains inadequate due to inherent magnetism. Here, we report a ligand‐mediated magnetism‐conversion nanoprobe (MCNP) composed of 3‐mercaptopropionic acid ligand‐coated silver‐gadolinium bimetallic nanoparticles. The MCNP exhibits a pH‐dependent magnetism conversion from ferromagnetism to diamagnetism, facilitating tunable nanomagnetism for pH‐activatable UHF MRI. Under neutral pH, the thiolate (−S−) ligands lead to short τ′m and increased magnetization of the MCNPs. Conversely, in the acidic tumor microenvironment, the thiolate ligands are protonated and transform into thiol (−SH) ligands, resulting in prolonged τ′m and decreased magnetization of the MCNP, thereby enhancing longitudinal relaxivity (r1) values at UHF MRI. Notably, under a 9 T MRI field, the pH‐sensitive changes in Ag−S binding affinity of the MCNP lead to a remarkable (>10‐fold) r1 increase in an acidic medium (pH 5.0). In vivo studies demonstrate the capability of MCNPs to amplify MRI signal of hepatic tumors, suggesting their potential as a next‐generation UHF‐tailored smart MRI contrast agent. [ABSTRACT FROM AUTHOR]

Cancer therapeutic vaccines are powerful tools for immune system activation and eliciting protective responses against tumors. However, their efficacy has often been hindered by weak and slow immune responses. Here, the authors introduce an immunization strategy employing senescent erythrocytes to facilitate the accumulation of immunomodulatory zinc‐Alum/ovalbumin (ZAlum/OVA) nanovaccines within both the spleen and solid tumors by temporarily saturating liver macrophages. This approach sets the stage for boosted cancer metalloimmunotherapy through a cascade immune activation. The accumulation of ZAlum/OVA nanovaccines in the spleen substantially enhances autophagy‐dependent antigen presentation in dendritic cells, rapidly initiating OVA‐specific T‐cell responses against solid tumors. Concurrently, ZAlum/OVA nanovaccines accumulated in the tumor microenvironment trigger immunogenic cell death, leading to the induction of individualized tumor‐associated antigen‐specific T cell responses and increased T cell infiltration. This erythrocyte‐assisted cascade immune activation using ZAlum/OVA nanovaccines results in rapid and robust antitumor immunity induction, holding great potential for clinical cancer metalloimmunotherapy. [ABSTRACT FROM AUTHOR]