Yi-Chun Yeh

MOF nanozymes couple programmable enzyme-mimetic catalysis with multimodal sensing, enabling sensitive and selective point-of-care biosensing.

Numerical simulations are performed to investigate the propagation, flow structure, and runout of turbidity currents in regimes where buoyancy-driven dynamics interact with finite settling effects. A Lagrangian particle-tracking framework is used to represent the evolving density field and its coupling with the carrier flow, enabling detailed analysis of current dynamics across multiple flow regimes. We first examine the temporal evolution of turbidity currents, which exhibit distinct slumping, propagation, and dissipation stages. The role of finite settling is shown to modulate density stratification and, in turn, the efficiency of momentum transfer within the current. We then analyse flow structure and deposition-induced feedbacks on the current dynamics. Transverse variations in the flow and deposition pattern are associated with lobe-and-cleft structures, while longitudinal variations arise from vortex detachment and decay. Finally, we propose a new scaling law for turbidity-current propagation speed and runout length that incorporates the combined effects of buoyancy forcing and settling-induced density evolution. The numerical results show close agreement with the proposed scaling, supporting its applicability to a wide class of particle-laden density currents. These results provide new insight into the dynamics of turbidity currents as geophysical density currents and contribute to improved predictive frameworks for buoyancy-driven flows in natural environments.

Metal–organic frameworks (MOFs) represent a category of crystalline porous materials that have attracted considerable interest owing to their structural flexibility and capacity to undergo reversible transformations in response to external stimuli. This review examines the underlying mechanisms that facilitate these structural changes, the various types of stimuli capable of inducing them, and the wide-ranging applications that capitalize on these dynamic properties. The discussion elucidates that the flexibility inherent in MOFs derives from several factors, including the characteristics of the metal cluster, the coordination geometry, the rigidity or flexibility of the organic linkers, and the overall topology of the framework. It is emphasized that minor alterations in these molecular-level attributes can result in significant variations in the structural behavior of MOFs, encompassing phenomena such as breathing, gate opening, and both negative and positive thermal expansion. Moreover, the review explores the experimental and computational methodologies employed to investigate MOF flexibility, incorporating in situ characterization techniques and molecular modeling approaches. It highlights how the interplay between framework design, guest interactions, and defect engineering can be strategically utilized to develop stimuli-responsive MOFs with customized functionalities suitable for applications in areas such as gas separation, gas storage, and sensing. In conclusion, the review underscores the importance of comprehending and manipulating structural transformations in MOFs, a consideration that has emerged as a key element in contemporary materials science and engineering.

Endotoxin detection is paramount for monitoring bacterial contamination in food, pharmaceuticals, and clinical diagnostics. The limulus amebocyte lysate (LAL) test, which relies on horseshoe crab blood, has long been the gold standard for endotoxin detection. However, the widespread adoption of this method is constrained by ethical concerns and the high costs associated with harvesting endangered species. Although nanozyme-based colorimetric methods present a more cost-effective and straightforward alternative, their application is limited by suboptimal selectivity and sensitivity. In this study, we report the synthesis and rigorous characterization of the bimetallic PCN-242 (Fe₂Co) metal–organic framework (MOF), synthesized using 2-amino terephthalic acid and a pre-synthesized [Fe₂Co(μ₃-O)(CH₃COO)₆] cluster. Steady-state kinetic analyses revealed that PCN-242 (Fe₂Co) MOF exhibits a significantly higher affinity for hydrogen peroxide (H₂O₂) compared to horseradish peroxidase (HRP) and other iron-based MOFs. The development of a PCN-242 (Fe₂Co)-based colorimetric sensor demonstrated a low limit of detection (LOD) of 1.36 μg mL⁻¹ for endotoxins, with excellent selectivity and reproducibility, thereby enabling effective detection of bacterial endotoxins. Recognizing the potential of the PCN-242 (Fe₂Co) MOF beyond endotoxin detection, we explored its utility in glucose biosensing. Moreover, incorporating glucose oxidase (GOx) into the PCN-242 (Fe₂Co) MOF framework further enhanced its peroxidase-like catalytic activity. This integration enabled sensitive glucose detection, achieving LODs of 4.24 μM for glucose and 2.2 μM for H₂O₂ within a linear range of 1 to 150 μM. The dual functionality of PCN-242 (Fe₂Co) MOF as a peroxidase mimic and biosensor platform highlights its potential for advanced catalytic and diagnostic applications, offering a versatile and ethical alternative to conventional methods.

Green-synthesized Cu-PyC NH₄⁺ MOF nanozyme demonstrates selective catecholase activity, distinct from typical oxidase nanozymes, enabling epigallocatechin gallate detection in tea samples.