SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3779-1
Comprehensive mechanical properties, including hardness (H), elastic modulus (E), fracture toughness (KC), and wear resistance, are essential for oxide ceramics used in demanding environments. This work employs nanoindentation to evaluate these properties for RE3TaO7 (RE=La, Sm, Eu, Gd, Dy, Lu) and identifies the optimal calculation method for KC in brittle oxide ceramics. The ratio of indentation crack length to half-diagonal (l/α) is a key parameter: Eq. (3) is suitable when l/α < 1, while Eq. (4) applies when l/α > 1. The indentation energy method is invalid for brittle ceramics due to crack formation at high loads. RE3TaO7 oxides exhibit H of 5.8–14.9 GPa, E of 127.5–247.8 GPa, and KC of 1.0–2.0 MPa·m1/2, surpassing RE2Zr2O7 (KC 1.0–1.5 MPa·m1/2). Wear resistance, indicated by MDP, ranges from 0.55 to 0.67, outperforming RE2Zr2O7. The superior fracture toughness is attributed to weberite structure with crack deflection and tortuous propagation, contrasted with pyrochlore's straight cracks. These findings provide accurate nanoindentation-based methods for assessing mechanical properties of brittle oxide ceramics, facilitating material discovery and optimization for thermal barrier coatings and other high-temperature applications.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-024-3281-x
Carbon monoxide (CO) therapy has emerged as a promising approach in cancer treatment. Selecting suitable nanocarriers for delivering manganese carbonyl (MnCO), a CO donor, while simultaneously regulating CO release and compensating for hydrogen peroxide (H2O2) and acidity in the tumor microenvironment is crucial for enhancing the effectiveness of CO therapy. In this study, a tumor microenvironment-responsive core-shell structured cascade nanoreactor was designed and synthesized using mesoporous polydopamine (MPDA) as a nanocarrier, followed by loading of MnCO and glucose oxidase-encapsulated zeolite imidazolate framework-8 (GOx@ZIF-8) nanoparticles. Upon entering cancer cells, the protective shell of GOx@ZIF-8 degrades in response to the acidic tumor environment, releasing GOx. GOx catalyzes the conversion of endogenous glucose into gluconic acid and H2O2, accelerating energy starvation in tumor cells. This process, in turn, promotes the reaction between MnCO and H2O2, resulting in in-situ amplified release of CO. Additionally, the excellent photothermal properties of MPDA enable photothermal therapy. This comprehensive antitumor strategy represents a promising advancement in the field of CO-based cancer therapy.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-025-3619-1
Inflammation and ischemic microenvironments represent significant challenges in cardiac repair. To address these issues, a series of dual-dynamically crosslinked alginate-based hydrogels (SA-PBA/E/Sr) containing strontium ions (Sr2+) and epigallocatechin gallate (EGCG) were developed, demonstrating microenvironment modulation and angiogenic capabilities in the myocardial infarction (MI) microenvironment. In the SA-PBA/E/Sr hydrogel system, alginate modified with aminophenylboronic acid (PBA) was synthesized to form boronic acid ester bonds with EGCG and an ionic coordination network with Sr2+ ions. The resulting hydrogel exhibits excellent injectability due to its dual-dynamically crosslinked structure, with its formation and mechanical properties being tunably modulated by the PBA substitution degree, EGCG concentration, and Sr2+ content. The incorporation of EGCG enables the hydrogel to efficiently scavenge reactive oxygen species (ROS) and mitigate oxidative stress-induced cellular damage under hypoxia. Furthermore, the introduction of Sr2+ significantly enhances the migratory capacity of endothelial cells, a critical factor in angiogenesis. In vivo experiments revealed that the injection of SA-PBA/E/Sr hydrogel into the infarcted myocardium of Sprague-Dawley (SD) rats led to reduced ROS levels, alleviated inflammatory responses, suppression of pro-inflammatory M1 macrophage expression, enhancement of anti-inflammatory M2 macrophage expression, and accelerated neovascularization in the damaged tissue. Echocardiographic and histological analyses demonstrated a remarkable increase in ejection fraction and a decreased infarct size, collectively indicating significant cardiac functional recovery.