The tumor microenvironment (TME) is characterized by elevated glutathione (GSH) levels and hypoxia, two interrelated pathological features that synergistically contribute to radioresistance. Conventional nanozymes, however, are constrained by intrinsically low catalytic efficiency, limited functional versatility, and inadequate biocompatibility, key limitations that collectively hinder their clinical translation. To overcome these barriers, we developed a hyaluronic acid-modified Pt@MnO2-Au-HA nanozyme with a well-defined core–shell–satellite architecture: a platinum (Pt) core, a conformal MnO2 interlayer, and spatially controlled gold (Au) nanoparticle satellites. Following intravenous administration, Pt@MnO2-Au-HA selectively targets proinflammatory macrophages in the tumor microenvironment via hyaluronic acid–mediated CD44 receptor recognition. Within the tumor, endogenously overexpressed hydrogen peroxide (H2O2) is catalytically decomposed into oxygen (O2) by the MnO2 component, which exhibits intrinsic catalase (CAT)-like activity. This O2 generation serves as an endogenous oxygen source to enhance glucose depletion via the glucose oxidase (GOx)-like activity of the Au component, thereby enabling starvation therapy. Concurrently, elevated intratumoral GSH induces the reductive dissolution of MnO2, resulting in both GSH consumption and controlled release of the Pt core. The liberated Pt nanoparticles further exert CAT-like activity to convert H2O2 into O2, effectively alleviating tumor hypoxia and synergistically amplifying radiotherapy efficacy through enhanced radiosensitization.
Radiation-induced skin injury (RISI) is one of the most common forms of tissue damage associated with radiotherapy and radiation exposure, facing a significant clinical challenge. Although natural products possess potent antioxidant and anti–inflammatory activities for radiation damage repair, their practical application is often limited by poor stability and low bioavailability. In this study, we constructed a natural product-derived self-assembled nanoparticle system (BRNPs) using resveratrol (Res) and berberine (BBR) to enhance cellular uptake and biocompatibility. A combined therapeutic system (BRNPs/SiO2 mixture) was developed for the treatment of RISI by combining BRNPs with SiO2 nanoparticles (SiO2 NPs). BRNPs/SiO2 mixture effectively scavenged intracellular ROS, reduced DNA damage and induced macrophage polarization toward the pro-regenerative M2 phenotype in vitro. In addition, this system markedly enhanced the cell migration of irradiated fibroblasts, endothelial tube formation and angiogenesis in vitro, thereby attenuating radiation-induced injury, accelerating wound healing and restoring skin barrier function in irradiated tissues of the RISI mouse model in vivo. These findings exhibited effective treatment of RISI via a combined strategy combining natural product-based nanomedicine and inorganic material.
Refractory high entropy alloys are known for their poor room temperature compressive formability, high temperature oxidation resistance and density while exhibiting substantial strength at room and elevated temperatures. In line with that, a low density Nb70Ti15Mo2W1.5Ta0.5Al10Cr1 complex lean alloy (Cr-1 CLA) is presented in the current work which exhibited excellent room temperature compressive strength-formability synergy while undergoing very controlled isothermal oxidation at 1000°C for 24 hrs exposure. This controlled oxidation in Cr-1 CLA is attributed to the formation of less permeable complex Nb-rich oxide layers (containing Al and Cr) at the surface thereby limiting the weight gain to 43.48 mg/cm2 upon exposure at 1000°C for 24 hrs. The improved compressive strength-formability synergy is a result of sustained work hardening at RT owing to two phase strengthening dominated deformation. Thus, the design of Cr-1 CLA opens a new pathway for realizing the light-weight refractory complex alloys overcoming the conventional oxidation concerns when exposed to higher temperature applications.
