SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3705-5
Biodegradable metals (BMs) are designed to corrode gradually in physiological environments, yet this corrosion can compromise their mechanical integrity, potentially causing premature implant failure. For emerging zinc-based alloys, the corrosion-mechanical property relationship remains inadequately characterized. This study systematically investigated the long-term corrosion-associated mechanical behavior of hot-extruded Zn-Cu and Zn-Cu-Fe alloys, promising Zn-based bio-metals, in comparison with pure Zn, under immersion degradation in Hank's solution. Electrochemical impedance spectroscopy and mechanical testing revealed that the evolving corrosion profile governs mechanical performance. Alloying with Cu and Fe mitigated corrosion's detrimental effects: grain refinement reduced localized corrosion susceptibility, while finely dispersed second phases acted as cathodic sites, promoting uniform corrosion. Additionally, Cu and Fe facilitated the formation of protective corrosion product layers, suppressing further matrix attack. Consequently, the overall reduced corrosion, particularly localized corrosion, lowered stress concentration susceptibility, delaying mechanical decline and preserving structural integrity. These findings elucidate the degradation-mechanical property correlation in Zn-based bio-metals and underscore critical considerations for developing new bio-metals for clinical translation.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4158-6
Near-infrared piezochromic materials exhibiting luminescence responses are critical for mechanical sensors and storage devices. Covalent organic frameworks (COFs), as crystalline porous materials, combine structural adaptability with tunable photophysical properties, yet their piezochromic applications remain underexplored. Here, we report a series of donor-acceptor structured two-dimensional COFs (2D COFs) with bright red emission, all showing pronounced red-shifts spanning red to near-infrared regions. Notably, Py-BO-COF exhibits the largest piezochromic shift of 187 nm with a high sensitivity of 44.52 nm GPa−1, significantly surpassing Py-BT-COF, TPE-BO-COF, and most reported COF/MOF systems. Py-BO-COF also demonstrates fully reversible and repeatable emission switching over multiple cycles, maintaining excellent linearity without degradation. In situ spectroscopic analyses and theoretical simulations reveal that variations in piezochromic rates arise from differences in charge-transfer (CT) processes, while the pronounced red-shift in Py-BO-COF is associated with reduced interlayer distance and enhanced coplanarity. This study systematically establishes the structure-property relationship in piezochromic 2D COFs, offering strategic guidance for designing highly sensitive and reversible pressure-responsive materials, thereby advancing smart piezochromic systems.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-025-3493-x
Bacterial infections impose a substantial clinical burden, with antibiotic resistance diminishing the efficacy of conventional therapeutics. Photodynamic therapy (PDT) offers a noninvasive antibacterial modality, yet existing photosensitizers suffer from insufficient free radical generation and limited functionality. This study reports a π-conjugated viologen derivative, 3TPhDPyMeOTf, incorporating multiple thiophene units to extend visible-light absorption and multiple pyridine structures to promote radical formation. Experimental and theoretical analyses confirm broad-spectrum antibacterial activity in vitro and in vivo. At 0.5 μM, the photosensitizer achieves over 60% eradication of Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA). In an MRSA-infected wound model, it accelerates healing with 93% efficacy within 12 days, significantly exceeding controls. The compound also exhibits excellent bacterial membrane staining, enabling bacterial imaging. This molecular design addresses the dual bottlenecks of weak visible-light absorption and inefficient radical generation in viologen-based photosensitizers, providing a promising strategy for potent PDT agents.