Currently, the development of advanced 2D nanomaterials has become an interdisciplinary subject with extensive studies due to their extraordinary physicochemical performances. Beyond graphene, the emerging 2D‐material‐derived electrocatalysts (2D‐ECs) have aroused great attention as one of the best candidates for heterogeneous electrocatalysis. The tunable physicochemical compositions and characteristics of 2D‐ECs enable rational structural engineering at the molecular/atomic levels to meet the requirements of different catalytic applications. Due to the lack of instructive and comprehensive reviews, here, the most recent advances in the nanostructure and catalytic center design and the corresponding structure–function relationships of emerging 2D‐ECs are systematically summarized. First, the synthetic pathways and state‐of‐the‐art strategies in the multifaceted structural engineering and catalytic center design of 2D‐ECs to promote their electrocatalytic activities, such as size and thickness, phase and strain engineering, heterojunctions, heteroatom doping, and defect engineering, are emphasized. Then, the representative applications of 2D‐ECs in electrocatalytic fields are depicted and summarized in detail. Finally, the current breakthroughs and primary challenges are highlighted and future directions to guide the perspectives for developing 2D‐ECs as highly efficient electrocatalytic nanoplatforms are clarified. This review provides a comprehensive understanding to engineer 2D‐ECs and may inspire many novel attempts and new catalytic applications across broad fields.
The microenvironments with high reactive-oxygen-species (ROS) levels, inflammatory responses, and oxidative-stress effects in diabetic ulcer wounds, leading to poor proliferation and differentiation of stem cells, severely inhibit their efficient healing. Here, to overcome the unbalanced multielectron reactions in ROS catalysis, we develop a cobalt selenide-based biocatalyst with an amorphous Ru@CoSe nanolayer for ultrafast and broadspectrum catalytic ROS-elimination. Owing to the enriched electrons and more unoccupied orbitals of Ru atoms, the amorphous Ru@CoSe nanolayer-equipped biocatalyst displays excellent catalase-like kinetics (maximal reaction velocity, 23.05 μM s −1 ; turnover number, 2.00 s −1 ), which exceeds most of the currently reported metal compounds. The theoretical studies show that Ru atoms act as "regulators" to tune the electronic state of the Co sites and modulate the interaction of oxygen intermediates, thus improving the reversible redox properties of active sites. Consequently, the Ru@CoSe can efficiently rescue the proliferation of mesenchymal stem cells and maintain their angiogenic potential in the oxidative stress environment. In vivo experiments reveal the superior ROS-elimination ability of Ru@CoSe on the inflammatory diabetic wound. This study offers an effective nanomedicine for catalytic ROS-scavenging and ultrafast healing of inflammatory wounds and also provides a strategy to design biocatalytic metal compounds via bringing amorphous catalytic structures.
Owing to their rich surface chemistry, high conductivity, tunable bandgap, and thermal stability, structured 2D transition‐metal carbides, nitrides, and carbonitrides (MXenes) with modulated atomic environments have emerged as efficient electrochemical energy conversion systems in the past decade. Herein, the most recent advances in the engineering of tunable structured MXenes as a powerful new platform for electrocatalytic energy conversion are comprehensively summarized. First, the state‐of‐the‐art synthetic and processing methods, tunable nanostructures, electronic properties, and modulation principles of engineering MXene‐derived nanoarchitectures are focused on. The current breakthroughs in the design of catalytic centers, atomic environments, and the corresponding structure–performance correlations, including termination engineering, heteroatom doping, defect engineering, heterojunctions, and alloying, are discussed. Furthermore, representative electrocatalytic applications of structured MXenes in energy conversion systems are also summarized. Finally, the challenges in and prospects for constructing MXene‐based electrocatalytic materials are also discussed. This review provides a leading‐edge understanding of the engineering of various MXene‐based electrocatalysts and offers theoretical and experimental guidance for prospective studies, thereby promoting the practical applications of tunable structured MXenes in electrocatalytic energy conversion systems.
Nanodrug carriers with fluorescence radiation are widely used in cancer diagnosis and therapy due to their real-time imaging, less side effect, better drug utilization as well as the good bioimaging ability. However, traditional nanocarriers still suffer from unexpectable drug leakage, unsatisfactory tumor-targeted drug delivery and shallow imaging depth, which limit their further application in cancer theranostics. In this study, an integrated nanoplatform is constructed by polymeric prodrug micelles with two-photon and aggregation-induced emission bioimaging, charge reversal and drug delivery triggered by acidic pH. The prodrug micelles can be self-assembled by the TP-PEI (DA/DOX)-PEG prodrug polymer, which consists of the two-photon fluorophore (TP), dimethylmaleic anhydride (DA) grafted polyethyleneimine (PEI) and polyethylene glycol (PEG). The PEG segment, DOX and DA are bridged to polymer by acid cleavable bonds, which provides the micelles a ‘stealth’ property and a satisfactory stability during blood circulation, while the outside PEG segment is abandoned along with the DA protection in the tumor acidic microenvironment, thus leading to charge reversal-mediated accelerated endocytosis and tumor-targeted drug delivery. The great antitumor efficacy and reduced side effect of these pH-sensitive prodrug micelles are confirmed by antitumor assays in vitro and in vivo. Meanwhile, these micelles exhibited great deep-tissue two-photon bioimaging ability up to 150 μm in depth. The great antitumor efficacy, reduced side effect and deep two-photon tissue imaging make the TP-PEI (DA/DOX)-PEG prodrug micelles would be an efficient strategy for theranostic nanoplatform in cancer treatment.
Periodontitis, one of the most common, challenging, and rapidly expanding oral diseases, is an oxidative stress-related disease caused by excessive reactive oxygen species (ROS) production. Developing ROS-scavenging materials to regulate the periodontium microenvironments is essential for treating periodontitis. Here, we report on creating cobalt oxide-supported Ir (CoO–Ir) as a cascade and ultrafast artificial antioxidase to alleviate local tissue inflammation and bone resorption in periodontitis. It is demonstrated that the Ir nanoclusters are uniformly supported on the CoO lattice, and there is stable chemical coupling and strong charge transfer from Co to Ir sites. Benefiting from its structural advantages, CoO–Ir presents cascade and ultrafast superoxide dismutase-catalase-like catalytic activities. Notably, it displays distinctly increased V max (76.249 mg L–1 min–1) and turnover number (2.736 s–1) when eliminating H2O2, which surpasses most of the by-far-reported artificial enzymes. Consequently, the CoO–Ir not only provides efficient cellular protection from ROS attack but also promotes osteogenetic differentiation in vitro. Furthermore, CoO–Ir can efficiently combat periodontitis by inhibiting inflammation-induced tissue destruction and promoting osteogenic regeneration. We believe that this report will shed meaningful light on creating cascade and ultrafast artificial antioxidases and offer an effective strategy to combat tissue inflammation and osteogenic resorption in oxidative stress-related diseases.
Colorimetric biosensing has become a popular sensing method for the portable detection of a variety of biomarkers. Artificial biocatalysts can replace traditional natural enzymes in the fields of enzymatic colorimetric biodetection; however, the exploration of new biocatalysts with efficient, stable, and specific biosensing reactions has remained challenging so far. Here, to enhance the active sites and overcome the sluggish kinetics of metal sulfides, the creation of an amorphous RuS 2 (a-RuS 2 ) biocatalytic system is reported, which can dramatically boost the peroxidase-mimetic activity of RuS 2 for the enzymatic detection of diverse biomolecules. Due to the existence of abundant accessible active sites and mildly surface oxidation, the a-RuS 2 biocatalyst displays a twofold V max value and much higher reaction kinetics/turnover number (1.63 × 10 −2 s −1 ) compared to that of the crystallized RuS 2 . Noticeably, the a-RuS 2 -based biosensor shows an extremely low detection limit of H 2 O 2 (3.25 × 10 −6 m), l-cysteine (3.39 × 10 −6 m), and glucose (9.84 × 10 −6 m), respectively, thus showing superior detection sensitivity to many currently reported peroxidase-mimetic nanomaterials. This work offers a new path to create highly sensitive and specific colorimetric biosensors in detecting biomolecules and also provides valuable insights for engineering robust enzyme-like biocatalysts via amorphization-modulated design.
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