Rational Design of Multisite Trielement Ru-Ni-Fe Alloy Nanocatalysts with Efficient and Durable Catalytic Hydrogenation Performances

RuZn NPs with electroactivity and oxidase-like property for dual-mode anti-cancer drug monitoring

6-mercaptopurine (6-MP) as the effective anti-cancer drug was used for the treatment of Crohn's disease and acute lymphoblastic leukaemia, but the response to maintenance therapy was variable with individual differences. In order to control the dosage and decrease the side effects of 6-MP, a sensitive and stable assay was urgently needed for 6-MP monitoring. Herein, RuZn NPs with electrochemical oxidation property and oxidase-like activity was proposed for dual-mode 6-MP monitoring. Burr-like RuZn NPs were prepared and explored to not only exhibit an electrochemical oxidation signal at 0.78 V, but also displayed excellent oxidase-like performances. RuZn NPs were utilized for the dual-mode monitoring of 6-MP, attributing to the formation of Ru-SH covalent bonding. The colorimetric method showed good linearity from 10 μM to 5 mM with the limit of detection (LOD) of 300 nM, while the electrochemical method provided a higher sensitivity with the LOD of 37 nM in range from 100 nM to 200 μM. This work provided a new way for the fabrication of dual-functional nanotags with electroactivity and oxidase-like property, and opened a dual-mode approach for the 6-MP detection applications with complementary and satisfactory results.

Biomimetic Chiral Nanomaterials with Selective Catalysis Activity

Chiral nanomaterials with unique chiral configurations and biocompatible ligands have been booming over the past decade for their interesting chiroptical effect, unique catalytical activity, and related bioapplications. The catalytic activity and selectivity of chiral nanomaterials have emerged as important topics, that can be potentially controlled and optimized by the rational biochemical design of nanomaterials. In this review, chiral nanomaterials synthesis, composition, and catalytic performances of different biohybrid chiral nanomaterials are discussed. The construction of chiral nanomaterials with multiscale chiral geometries along with the underlying principles for enhancing chiroptical responses are highlighted. Various biochemical approaches to regulate the selectivity and catalytic activity of chiral nanomaterials for biocatalysis are also summarized. Furthermore, attention is paid to specific chiral ligands, materials compositions, structure characteristics, and so on for introducing selective catalytic activities of representative chiral nanomaterials, with emphasis on substrates including small molecules, biological macromolecule, and in-site catalysis in living systems. Promising progress has also been emphasized in chiral nanomaterials featuring structural versatility and improved chiral responses that gave rise to unprecedented chances to utilize light for biocatalytic applications. In summary, the challenges, future trends, and prospects associated with chiral nanomaterials for catalysis are comprehensively proposed.

Ruthenium-Encapsulated Porphyrinic Organic Polymer as a Photoresponsive Oxidoreductase Mimetic Nanozyme for Colorimetric Sensing

The advantages of porosity and stable unpaired electrons of porphyrinic organic polymers (POPs) with free radicals are exclusive and potentially practical functionalities and combining the semiconductor-like characteristics of these materials and metal ions has been an effective way to assemble an efficient photocatalytic system. Herein, a new ruthenium (Ru) ion-encapsulated porphyrinic organic polymer (POP/Ru) is facilely synthesized as a proper photoresponsive nanozyme with unique photo-oxidase properties. Surprisingly, the proposed POP/Ru revealed outstanding photoresponsive oxidase-mimicking activity due to the synergetic effect of the integration of Ru and π-electrons of POP, which boosts charge separation and transport. POP/Ru was applied to the oxidation of o-phenylenediamine (o-PDA) as a chromogenic probe for producing a colorimetric signal. The kinetic study reveals that these photo-oxidase mimics have a significant affinity for the o-PDA chromogenic agent owing to a lower K_m and superior V_max. Further findings demonstrate that the presence of the l-arginine (l-Arg) target causes an inhibition effect on the photo-nanozymatic colorimetry of POP/Ru. This research develops the applications of the comprehensive colorimetric strategy for ultrasensitive l-Arg monitoring with a limit of detection (LOD) of 15.2 nM in the dynamic range of 4.0 nM-340 μM and illuminates that the proposed photo-oxidase nanozyme as a visual strategy is feasible in l-Arg environmentally friendly colorimetric detection in juice samples.

Versatile Au@Ru nanocomposites for the rapid detection of Salmonella typhimurium and photothermal sterilization

In view of the current public health hazards of food-borne pathogens, it is urgent to develop a rapid detection method with high sensitivity, good specificity and operational convenience, as well as to determine an effective sterilization strategy. Herein, versatile gold-ruthenium nanocomposites modified with antibody (Au@Ru-pAb Ncs) have been constructed for the sensitive detection of Salmonella typhimurium (S. typhimurium) via the lateral flow immunochromatographic assay (LFIA). Au@Ru-pAb Ncs based LFIA exhibited a wide detection range from 2.9 × 10⁶ CFU/mL to 2.9 × 10¹¹ CFU/mL with the limit of detection of 9.8 × 10⁴ CFU/mL for S. typhimurium, and displayed excellent specificity. In addition, Au@Ru-pAb Ncs irradiated with 808 nm (500 mW/cm²) near-infrared light (NIR) had a significant antibacterial effect within only 5 min, attributed to its high photothermal conversion efficiency of 54.14%. Therefore, both sensitive detection of S. typhimurium and effective NIR-triggered photothermal sterilization were achieved by using versatile Au@Ru-pAb Ncs, showing great prospects in the field of pathogen detection and treatment.

AuPt NPs with enhanced electrochemical oxidization activity for ratiometric electrochemical aptasensor

Strong and stable electrochemical beacons are critical for the achievement of sensitive and reliable electroanalysis applications. In this work, the electrochemical oxidation performance of AuPt NPs was studied and firstly found to be largely enhanced under light illumination. Plasmonic AuPt NPs collected light energy after local surface plasmon resonance (LSPR) excitation and generated much more holes to participate in the electrochemical oxidation process of Pt⁰ in AuPt NPs. AuPt NPs with the electrochemical oxidation peak at around -0.7 V were utilized as detection probes for the fabrication of ratiometric electrochemical aptasensor, by introducing Co-MOF/Fe₃O₄/Ag nanosheets (NSs) with the electrochemical oxidation peak at 0.1 V as reference beacons. The aptamers of epithelial cell adhesion molecule (EpCAM) modified AuPt NPs were assembled with Co-MOF/Fe₃O₄/Ag NSs, which generated strong detection and reference signals at -0.7 V and 0.1 V, respectively. The high affinity between EpCAM and aptamers induced the separation of AuPt NPs from Co-MOF/Fe₃O₄/Ag NSs, resulting in the decrease of detection signal at -0.7 V and unchanged reference signal at 0.1 V. A ratiometric electrochemical aptasensor was achieved for the sensitive and reliable quantification of EpCAM in the range from 100 pg/mL to 100 ng/mL. The limit of detection (LOD) was calculated to be 13.8 pg/mL for EpCAM. Plasmon-driven electrochemical oxidation enhancement principle provides the possibility for the design and fabrication of more strong and anti-interference electroactive plasmonic metal-Pt composite nanostructures for the electroanalysis applications.

RuCu Cage/Alloy Nanoparticles with Controllable Electroactivity for Specific Electroanalysis Applications

Electrochemical nanotags with controllable and multiresponse electroactivity have a great capacity for overcoming the drawbacks of limited target monitoring and inaccurate detection results for electrochemical sensors. In this contribution, double electro-oxidative Ru and Cu metals were integrated into RuCu nanostructures for the generation of dual electro-oxidative signals. A facial approach was proposed for the controllable fabrication of RuCu cage nanoparticles (NPs) and RuCu alloy NPs by simply adjusting the pH value of the reaction system. RuCu cage NPs and RuCu alloy NPs demonstrated inherent different electro-oxidative responses owing to the remarkable distinction of structures with different metal valences. RuCu cage NPs showed a single electro-oxidization peak at 0.84 V, assigned to the exposure of more Ru⁰ electroactive sites on the hollow cage structures. RuCu alloy NPs illustrated dual electro-oxidization peak at 0.84 and -0.16 V, attributing to the presence of Ru⁰ and Cu⁺ electroactive sites on the alloy structures, respectively. RuCu cage NPs and RuCu alloy NPs served as specific electroactive tags, achieving the selective monitoring of Na₂S and ratiometric electrochemical detection of xanthine in monosodium glutamate, respectively. The limits of detection were as low as 27 pM for Na₂S and 70 nM for xanthine. The rational design of multimetal nanostructures holds enormous potential for the generation of multiresponse electroactivity with the impetus for exploring the capacity of specific electrochemical sensing.

Plasmon-Enhanced Electroactivity of AuRu Nanostructures for Electroanalysis Applications

An electrochemical sensing interface is limited by poor reproducibility and inevitable interferences present in practical applications due to the weak electrochemical signals of nanotags. This motivates the need for effective strategies to enhance the electroactivity performances of nanotags. In this contribution, a plasmon-enhanced electroactivity mechanism is proposed for AuRu-based nanostructures under illumination and applied for accurate detection of human epidermal growth factor receptor-2 (HER2). AuRu nanoparticles (NPs) harvested light energy through plasmon excitation and generated holes to participate in the electrooxidation process. The production of holes resulted in the electrooxidation signal enhancement of AuRu NPs. AuRu NPs were assembled with Au NPs using HER2 aptamers as linkers, and the plasmonic coupling between AuRu NPs and Au NPs produced an intense electromagnetic field, which further enhanced the electrooxidation signals of AuRu NPs. An AuRu-Au NP assembly-dependent electrochemical aptasensor was established for the accurate detection of HER2, and the limit of detection (LOD) was as low as 1.7 pg/mL. The plasmon-enhanced electroactivity mechanism endowed AuRu-based nanostructures with strong and noninterfering electrochemical signals for sensitive and accurate detection. This insight opens new horizons for the construction of desired electroactive nanostructures for electroanalysis applications.

Intriguing hierarchical Co@NC microflowers in situ assembled by nanoneedles: Towards enhanced reduction of nitroaromatic compounds via interfacial synergistic catalysis

Developing highly efficient and cost-effective catalyst with tuned microstructure holds great promise in the reduction of nitroaromatic compounds under mild reaction conditions. Herein, we report a new Co@NC-MF catalyst with a fascinating hierarchical flower-like architecture in situ assembled from uniform Co@NC nanoneedles, which can function as a favorable platform for the efficient reduction of nitroaromatic compounds in the presence of NaBH₄. In addition with the structural advantage, the characterization and experimental results demonstrate the enormous advantage of interfacial synergistic catalysis in enhancing the catalytic performance. The outside electron-rich N-doped carbon layer as Lewis basic sites and the inside Co nanoparticles are responsible for the adsorption of 4-nitrophenol (4-NP) and generation of active hydrogen species, respectively. This work contributes to the construction of well-integrated composites with well-balanced interface synergy to boost the catalytic performance in various heterogeneous reactions.

Rational Design of Ruthenium and Cobalt-Based Composites with Rich Metal-Insulator Interfaces for Efficient and Stable Overall Water Splitting in Acidic Electrolyte

The great promise of hydrogen energy and hydrogen production from water through proton exchange membrane (PEM) or membrane-free electrolysis drives the pursuit of highly active and acid-stable electrocatalysts with dual functionality and reduced cost for overall water splitting in acidic media. Here, we report a new Ru-modified cobalt-based electrocatalyst embedded in a nitrogen-doped carbon (NC) matrix with rationally designed Mott-Schottky heterostructure to realize high activity and stability toward overall water splitting in a strongly acidic environment. Such a composite was facilely prepared by carbonization of cobalt-based MOF, followed by galvanic exchange between cobalt and Ru, and then controlled partial oxidation. The partial oxidation of RuCo implanted inside the NC matrix led to the formation of a class of RuO₂/Co₃O₄-RuCo@NC composites with rich metal-semiconductor interfaces to facilitate the charge-transfer process. As a result, the composite displayed remarkable electrocatalytic activity toward both oxygen/hydrogen evolutions in acidic media. Significantly, they also afforded low overpotentials of 247 and 141 mV for OER and HER, respectively, and a cell voltage of 1.66 V for overall water splitting at 10 mA cm^-2. In addition, excellent operation stability in 0.5 M H₂SO₄ solutions, comparable to those of them working in alkaline conditions, is demonstrated due to the protection of a coated carbon thin film. The presented work opens a new opportunity toward designing bifunctional electrocatalysts for acidic water electrolysis.