Nanozymes are nanomaterial-based artificial enzymes.

Immuno-positron emission tomography (immunoPET) is a paradigmshifting molecular imaging modality combining the superior targeting specificity of monoclonal antibody (mAb) and the inherent sensitivity of PET technique. A variety of radionuclides and mAbs have been exploited to develop immunoPET probes, which has been driven by the development and optimization of radiochemistry and conjugation strategies. In addition, tumor-targeting vectors with a short circulation time (e.g., Nanobody) or with an enhanced binding affinity (e.g., bispecific antibody) are being used to design novel immunoPET probes. Accordingly, several immunoPET probes, such as 89 Zr-Df-pertuzumab and 89 Zr-atezolizumab, have been successfully translated for clinical use. By noninvasively and dynamically revealing the expression of heterogeneous tumor antigens, immunoPET imaging is gradually changing the theranostic landscape of several types of malignancies. ImmunoPET is the method of choice for imaging specific tumor markers, immune cells, immune checkpoints, and inflammatory processes. Furthermore, the integration of immunoPET imaging in antibody drug development is of substantial significance because it provides pivotal information regarding antibody targeting abilities and distribution profiles. Herein, we present the latest immunoPET imaging strategies and their preclinical and clinical applications. We also emphasize current conjugation strategies that can be leveraged to develop next-generation immunoPET probes. Lastly, we discuss practical considerations to tune the development and translation of immunoPET imaging strategies.

The mononuclear phagocyte system (MPS, e.g., liver and spleen) is often treated as a 'blackbox' by nano-researchers in translating nanomedicines. Often, most of the injected nanomaterials are sequestered by the MPS, preventing their delivery to the desired disease areas. Here, we exploit this imperfection by applying nano-antioxidants with preferential liver uptake to directly prevent hepatic ischemia-reperfusion injury (IRI), which is a reactive oxygen species (ROS)related disease. Ceria nanoparticles (NPs) were selected as a representative nano-antioxidant and detailed mechanism of preventing IRI was investigated. We found that ceria NPs effectively alleviated the clinical symptoms of hepatic IRI by scavenging ROS, inhibiting activation of Kupffer cells and monocyte/macrophage cells. The released pro-inflammatory cytokines were then significantly reduced and the recruitment and infiltration of neutrophils were minimized, which suppressed subsequent inflammatory reaction involved in the liver. The protective effect of nanoantioxidants against hepatic IRI in living animals and the revealed mechanism herein suggests their future use for the treatment of hepatic IRI in the clinic.