Oxidoreductase is the largest class of enzymes and has broad applications in biotechnology since a number of bioconversions involve oxidation/reduction reactions. Coenzymes are always required in oxidoreductase-catalyzed reactions, where nicotinamide coenzymes, NAD(P)H/NAD(P) + , are the most commonly used. They undergo reactions with substrates in biocatalytic processes by converting into their reductive or oxidative forms. The efficient and economical regeneration of nicotinamide coenzymes is therefore of particular significance for industrial applications due to their high cost and large usage. The principal methods used for the regeneration of nicotinamide coenzymes, including enzymatic, chemical, electrochemical and photochemical regeneration methods are surveyed with emphasis on the crucial issues and the state-of-art research relevant to each method. Screening and improving the performance of the enzymes, designing and implementing efficient regeneration routes as well as retaining/recycling coenzymes are the three key issues for the enzymatic method. Development of efficient catalysts with high selectivity is the top priority of the chemical regeneration method. For the electrochemical regeneration method, improvement of the electrode by modification of either the nano-materials or electron mediators is the major concern. The focus of the photochemical regeneration method lies in the exploitation of efficient visible-light photosensitizers.

The transmetalation (the replacement of metal ions) of a family of highly porous isostructural metal−organic frameworks (MOFs), M 6 (BTB) 4 (BP) 3 (where M = Zn(II) (1), Co(II) (2), Cu(II) (3), and Ni(II) (4), BTB = 1,3,5benzenetribenzoate, and BP = 4,4′-dipyridyl) with an ith-d net topology has been investigated. These compounds have different framework stabilities depending on the framework metal ions. The transmetalation and the reverse transmetalation reactions of the framework metal ions were observed between the MOFs, 1 and 2, having a similar thermodynamic stability. While the transmetalation from thermodynamically less stable 1 and 2 to more stable 3 and 4 were achieved by soaking single crystals of 1 and 2 in a solution of N,N′-dimethylformamide (DMF) containing Cu(II) and Ni(II) ions, respectively, no reverse transmetalation was observed. By simply controlling the soaking time, not only could homogeneously transmetalated crystalline framework structures be prepared via the thermodynamically controlled complete replacement of the framework metal ions but also selectively transmetalated core−shell heterostructures were formed via kinetically controlled replacement that was mainly restricted to the external shell region of the crystal. The fully transmetalated MOFs showed significantly improved framework stabilities compared with the parent MOFs. A marked improvement in the framework stability was observed, even in the selectively transmetalated Co(II)/Cu(II)-and Co(II)/Ni(II)-core−shell heterostructures. Although the frameworks are partially transmetalated, the framework stability of not only the external shell region but also of the internal core region was significantly affected.

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An efficient multienzyme cascade system based on ultrathin, hybrid microcapsules was constructed for converting CO2 to methanol by combining the unique functions of catechol and gelatin. Gelatin was modified with catechol groups (GelC) via well-defined EDC/NHS chemistry, thus endowed with the ability to covalently attach enzyme molecules. Next, the first enzyme (FateDH)-containing CaCO3 templates were synthesized via coprecipitation and coated with a GelC layer. Afterward, GelC was covalently attached with the second enzyme (FaldDH) via Michael addition and Schiff base reactions. Then, GelC induced the hydrolysis and condensation of silicate, and the third enzyme (YADH) was entrapped accompanying the formation of silica particles. After removal of CaCO3 templates, the GelCSi-based multienzyme system was obtained, in which the three enzymes were appropriately positioned in different places of the GelCSi microcapsules, and the amount of individual enzyme was regulated according to enzyme activity. The system exhibited high activity and stability for converting CO2 into methanol. In detail, the system displayed much higher methanol yield and selectivity (71.6%, 86.7%) than that of multienzyme in free form (35.5%, 47.3%). The methanol yield remained 52.6% after nine times of recycling. This study will provide some guidance on constructing diverse scaffolds for applications in catalysis, drug and gene delivery, and biosensors.

Microcapsules with diverse wall structures may exhibit different performance in specific applications. In the present study, three kinds of mussel-inspired polydopamine (PDA) microcapsules with different wall structures have been prepared by a template-mediated method. More specifically, three types of CaCO3 microspheres (poly(allylamine hydrochloride), (PAH)-doped CaCO3; pure-CaCO3; and poly(styrene sulfonate sodium), (PSS)-doped CaCO3) were synthesized as sacrificial templates, which were then treated by dopamine to obtain the corresponding PDA-CaCO3 microspheres. Through treating these microspheres with disodium ethylene diamine tetraacetic acid (EDTA-2Na) to remove CaCO3, three types of PDA microcapsules were acquired: that was (1) PAH-PDA microcapsule with a thick (∼600 nm) and highly porous capsule wall composed of interconnected networks, (2) pure-PDA microcapsule with a thick (∼600 nm) and less porous capsule wall, (3) PSS-PDA microcapsule with a thin (∼70 nm) and dense capsule wall. Several characterizations confirmed that a higher degree in porosity and interconnectivity of the capsule wall would lead to a higher mass transfer coefficient. When serving as the carrier for catalase (CAT) immobilization, these enzyme-encapsulated PDA microcapsules showed distinct structure-related activity and stability. In particular, PAH-PDA microcapsules with a wall of highly interconnected networks displayed several significant advantages, including increases in enzyme encapsulation efficiency and enzyme activity/stability and a decrease in enzyme leaching in comparison with other two types of PDA microcapsules. Besides, this hierarchically structured PAH-PDA microcapsule may find other promising applications in biocatalysis, biosensors, drug delivery, etc.

A “three birds one stone” strategy for preparing 1D N-doped porous carbon nanotubes embedded with Co@CoOx nanoparticles results in the unprecedentedly high-rate Zn–air batteries.

: Understanding the interaction between salinity and nitrogen (N) nutrition is of great economic importance to improve plant growth and grain yield for oat plants. The objective of this study was to investigate whether N application could alleviate the negative effect of salinity (NaCl) stress on oat physiological parameters and yield performance. Two oat genotypes with contrasting salt tolerance response (6-SA120097, a salt-tolerant genotype SA and 153-ND121147, salt-sensitive ND) were grown under four N rates (0, 100, 200, and 400 mg N pot−1) in non-saline and saline (100 mM NaCl) conditions. The results showed that salinity, N fertilization and their interaction significantly affected the photosynthetic rate, transpiration rate, agronomic nitrogen use efficiency (aNUE), physiological nitrogen efficiency (pNUE) and apparent nitrogen recovery (ANR), seed number, and grain yield. Saline stress reduced gas exchange rate, nitrogen use efficiency (NUE), grain yield, and yield components. N fertilization increased photosynthetic productivity and chlorophyll fluorescence, resulting in improved grain yields and yield components for both genotypes. On average, the photosynthetic rate was increased by 38.7%, 74.1%, and 98.8% for SA and by 49.8%, 77.6%, and 110% for ND, respectively, under the N rates of 100, 200, and 400 mg N pot−1, as compared with non-fertilized treatment. In addition, grain yield was increased by 80.6% for genotype SA and 88.7% for genotype ND under higher N application rate (200 mg N pot−1) in comparison with the non-nitrogen treatment. Our experimental results showed that an increase of N supply can alleviate the negative effects induced by salinity stress and improved plant growth and yield by maintaining the integrity of the photosynthesis and chlorophyll fluorescence processes of oat plants, which provides a valuable agronomic strategy for improving oat production in salt-affected soils.

Lithium−sulfur batteries are getting more attention in energy storage and conversion fields due to their high theoretical capacity and specific energy density. Nevertheless, the dissolution of polysulfides results in their poor cycle stability, which is the major issue in practical use. To overcome the challenge, we report a new strategy by employing a redox-active covalent organic framework as the separator in lithium−sulfur batteries. The one-dimensional pore channels of the covalent organic framework provide a fast transport pathway for the lithium ion. And the pyridine units of the framework not only enhance the chemical adsorption of sulfur but also catalyze the charge and discharge processes. By virtue of these features, the specific capacity at 0.2 C is 977 mAh g −1 after 100 cycles, which is 5.2 times higher than that of the pristine separator-based battery. Additionally, the specific capacity achieves 826 mAh g −1 at 1 C after 250 cycles.