Self-Assembled Zeolitic Imidazolate Framework/CdS Hollow Microspheres with Efficient Charge Separation for Enhanced Photocatalytic Hydrogen Evolution

Construction of a hollow heterojunction interface to accelerate the photocatalytic cleavage of lignin Cβ-O bonds

Photocatalytic splitting of the Cβ-O bond is regarded as a prospective strategy for transforming lignin, and it is imperative to develop novel photocatalysts with effective photogenerated charges separation and solar absorption capacity. Herein, a novel hollow ZIF-8/CdS heterostructure photocatalyst was synthesized for the catalytic splitting of lignin Cβ-O bonds. The photocatalytic cleavage rate of Cβ-O bond of ligin β-O-4 reached 30.3∙mmol∙h-1∙g-1 within 20 min under visible light exposure. It is noteworthy that the utilization of intricate natural lignin molecules in this photocatalytic system has yielded successful depolymerization. The DFT and XPS results indicate a potential unidirectional electron migration from ZIF-8 to CdS in ZIF-8/CdS composites transfer. This electron transport path follows the direct Z-scheme heterostructure mechanism, resulting in the generation of an internal electric field between ZIF-8 and CdS. Impressively, the synergistic combination of the hollow structure and Z-scheme heterostructure effectively enhances the efficiency of charge carrier separation and maintains a robust redox potential, thereby facilitating Cα-radical generation. This study proposes a novel photocatalyst design strategy that integrates hollow structures and Z-scheme heterojunctions, with the aim of targeting the depolymerization of the Cβ-O bond in lignin.

An immunosensor for the near real-time and site of inflammation detections of multiple proinflammatory cytokines

Diseases mediated by cytokine storms are often characterized by an overexuberant pace of pathogenesis accompanied by significant morbidity and mortality. Thus, near real-time (NRT) detections via a site-of-inflammation (SOI) sampling of proinflammatory cytokines are essential to ensure a timely and effective treatment of acute inflammations, which up to now, has not been fully possible. In this work, we proposed a novel NRT and SOI immunosensor using ZIF-8 signal amplification together with an off-on strategy. To achieve NRT detections via a SOI sampling, the body fluid of choice is the dermal interstitial fluid (ISF). The significant merits of ISF over blood are the quality, quantity and diversity of ISF-based biomarkers; the fluid is non-coagulating, making it feasible to perform multiple or continuous samplings and the sampling is minimally invasive. Our immunosensor requires only 5 μL of ISF to achieve a simultaneous detection of five highly potent proinflammatory cytokines: IL-6, IFN-γ, IL-1β, TNF-α, IP-10. We employed a microneedle array patch (MAP) together with a trifurcated nozzle pump to extract a mean volume of between 30 and 60 μL of ISF in 20 min. Under optimal conditions, the biosensor is capable of high-quality performance that exhibits a lower limit of detection (LOD) of 5.761 pg/mL over a wide linear range of 5.761-3 ‒ 20.00 ng/mL. We believe our immunosensor for NRT detections via a SOI sampling of ISF-biomarkers offers new theranostic opportunities that may not be possible with blood-based biomarkers.

Advances in zeolitic-imidazolate-framework-based catalysts for photo-/electrocatalytic water splitting, CO2 reduction and N2 reduction applications

Harnessing electrical or solar energy for the renewable production of value-added fuels and chemicals through catalytic processes (such as photocatalysis and electrocatalysis) is promising to achieve the goal of carbon neutrality. Owing to the large number of highly accessible active sites, highly porous structure, and charge separation/transfer ability, as well as excellent stability against chemical and electrochemical corrosion, zeolite imidazolate framework (ZIF)-based catalysts have attracted significant attention. Strategic construction of heterojunctions, and alteration of the metal node and the organic ligand of the ZIFs effectively regulate the binding energy of intermediates and the reaction energy barriers that allow tunable catalytic activity and selectivity of a product during reaction. Focusing on the currently existing critical issues of insufficient kinetics for electron transport and selective generation of ideal products, this review starts from the characteristics and physiochemical advantages of ZIFs in catalytic applications, then introduces promising regulatory approaches for advancing the kinetic process in emerging CO2 reduction, water splitting and N2 reduction applications, before proposing perspective modification directions.

Synthesis of Metal-Organic Framework-Based ZIF-8@ZIF-67 Nanocomposites for Antibiotic Decomposition and Antibacterial Activities

Toxic antibiotic effluents and antibiotic-resistant bacteria constitute a threat to global health. So, scientists are investigating high-performance materials for antibiotic decomposition and antibacterial activities. In this novel research work, we have successfully designed ZIF-8@ZIF-67 nanocomposites via sol-gel and solvothermal approaches. The ZIF-8@ZIF-67 nanocomposite is characterized by various techniques that exhibit superior surface area enhancement, charge separation, and high light absorption performance. Yet, ZIF-8 has high adsorption rates and active sites, while ZIF-67 has larger pore volume and efficient adsorption and reaction capabilities, demonstrating that the ZIF-8@ZIF-67 nanocomposite outperforms pristine ZIF-8 and ZIF-67. Compared with pristine ZIF-8 and ZIF-67, the most active 6ZIF-67@ZIF-8 nanocomposite showed higher decomposition efficacy for ciprofloxacin (65%), levofloxacin (54%), and ofloxacin (48%). Scavenger experiments confirmed that •OH, •O2-, and h+ are the most active species for the decomposition of ciprofloxacin (CIP), levofloxacin (LF), and ofloxacin (OFX), respectively. In addition, the 6ZIF-67/ZIF-8 nanocomposite suggested its potential applications in Escherichia coli for growth inhibition zone, antibacterial activity, and decreased viability. Moreover, the stability test and decomposition pathway of CIP, LF, and OFX were also proposed. Finally, our study aims to enhance the efficiency and stability of ZIF-8@ZIF-67 nanocomposite and potentially enable its applications in antibiotic decomposition, antibacterial activities, and environmental remediation.

Metallocavitins as Advanced Enzyme Mimics and Promising Chemical Catalysts

The supramolecular approach is becoming increasingly dominant in biomimetics and chemical catalysis due to the expansion of the enzyme active center idea, which now includes binding cavities (hydrophobic pockets), channels and canals for transporting substrates and products. For a long time, the mimetic strategy was mainly focused on the first coordination sphere of the metal ion. Understanding that a highly organized cavity-like enzymatic pocket plays a key role in the sophisticated functionality of enzymes and that the activity and selectivity of natural metalloenzymes are due to the effects of the second coordination sphere, created by the protein framework, opens up new perspectives in biomimetic chemistry and catalysis. There are two main goals of mimicking enzymatic catalysis: (1) scientific curiosity to gain insight into the mysterious nature of enzymes, and (2) practical tasks of mankind: to learn from nature and adopt from its many years of evolutionary experience. Understanding the chemistry within the enzyme nanocavity (confinement effect) requires the use of relatively simple model systems. The performance of the transition metal catalyst increases due to its retention in molecular nanocontainers (cavitins). Given the greater potential of chemical synthesis, it is hoped that these promising bioinspired catalysts will achieve catalytic efficiency and selectivity comparable to and even superior to the creations of nature. Now it is obvious that the cavity structure of molecular nanocontainers and the real possibility of modifying their cavities provide unlimited possibilities for simulating the active centers of metalloenzymes. This review will focus on how chemical reactivity is controlled in a well-defined cavitin nanospace. The author also intends to discuss advanced metal–cavitin catalysts related to the study of the main stages of artificial photosynthesis, including energy transfer and storage, water oxidation and proton reduction, as well as highlight the current challenges of activating small molecules, such as H2O, CO2, N2, O2, H2, and CH4.