A novel anode material for sodium-ion batteries consisting of 3D graphene microspheres divided into several tens of uniform nanospheres coated with few-layered MoS 2 by a one-pot spray pyrolysis process is prepared. The fi rst discharge/charge capacities of the composite microspheres are 797 and 573 mA h g −1 at a current density of 0.2 A g −1. The 600th discharge capacity of the composite microspheres at a current density of 1.5 A g −1 is 322 mA h g −1 .The Coulombic effi ciency during the 600 cycles is as high as 99.98%. The outstanding Na ion storage properties of the 3D MoS 2 -graphene composite microspheres may be attributed to the reduced stacking of the MoS 2 layers and to the 3D structure of the porous graphene microspheres. The reduced stacking of the MoS 2 layers relaxes the strain and lowers the barrier for Na + insertion. The empty nanospheres of the graphene offer voids for volume expansion and pathways for fast electron transfer during repeated cycling.

Enzymes found in nature have been exploited in industry due to their inherent catalytic properties in complex chemical processes under mild experimental and environmental conditions. The desired industrial goal is often difficult to achieve using the native form of the enzyme. Recent developments in protein engineering have revolutionized the development of commercially available enzymes into better industrial catalysts. Protein engineering aims at modifying the sequence of a protein, and hence its structure, to create enzymes with improved functional properties such as stability, specific activity, inhibition by reaction products, and selectivity towards non-natural substrates. Soluble enzymes are often immobilized onto solid insoluble supports to be reused in continuous processes and to facilitate the economical recovery of the enzyme after the reaction without any significant loss to its biochemical properties. Immobilization confers considerable stability towards temperature variations and organic solvents. Multipoint and multisubunit covalent attachments of enzymes on appropriately functionalized supports via linkers provide rigidity to the immobilized enzyme structure, ultimately resulting in improved enzyme stability. Protein engineering and immobilization techniques are sequential and compatible approaches for the improvement of enzyme properties. The present review highlights and summarizes various studies that have aimed to improve the biochemical properties of industrially significant enzymes.

Natural photosynthesis is an effective route for the clean and sustainable conversion of CO into high-energy chemicals. Inspired by the natural process, a tandem photoelectrochemical (PEC) cell with an integrated enzyme-cascade (TPIEC) system was designed, which transfers photogenerated electrons to a multienzyme cascade for the biocatalyzed reduction of CO to methanol. A hematite photoanode and a bismuth ferrite photocathode were applied to fabricate the iron oxide based tandem PEC cell for visible-light-assisted regeneration of the nicotinamide cofactor (NADH). The cell utilized water as an electron donor and spontaneously regenerated NADH. To complete the TPIEC system, a superior three-dehydrogenase cascade system was employed in the cathodic part of the PEC cell. Under applied bias, the TPIEC system achieved a high methanol conversion output of 220 μm h , 1280 μmol g h using readily available solar energy and water.

Erythritol, a four-carbon polyol, is a biological sweetener with applications in food and pharmaceutical industries. It is also used as a functional sugar substitute in special foods for people with diabetes and obesity because of its unique nutritional properties. Erythritol is produced by microbial methods using mostly osmophilic yeasts and has been produced commercially using mutant strains of Aureobasidium sp. and Pseudozyma tsukubaensis. Due to the high yield and productivity in the industrial scale of production, erythritol serves as an inexpensive starting material for the production of other sugars. This review focuses on the approaches for the efficient erythritol production, strategies used to enhance erythritol productivity in microbes, and the potential biotechnological applications of erythritol.

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A novel type of spherical and porous composites were synthesized to dually benefit from reduced graphene oxide (rGO) and magnetic materials as supports for enzyme immobilization. Three magnetic composite particles of FeO and rGO containing 71% (rGO-FeO-M1), 36% (rGO-FeO-M2), and 18% (rGO-FeO-M3) Fe were prepared using a one-pot spray pyrolysis method and were used for the immobilization of the model enzymes, laccase and horseradish peroxidase (HRP). The rGO-FeO composite particles prepared by spray pyrolysis process had a regular shape, finite size, and uniform composition. The immobilization of laccase and HRP on rGO-FeO-M1 resulted in 112 and 89.8% immobilization efficiency higher than that of synthesized pure FeO and rGO particles, respectively. The stability of laccase was improved by approximately 15-fold at 25 °C. Furthermore, rGO-FeO-M1-immobilized laccase exhibited 92.6% of residual activity after 10 cycles of reuse and was 192% more efficient in oxidizing different phenolic compounds than the free enzyme. Therefore, these unique composite particles containing rGO and FeO may be promising supports for the efficient immobilization of industrially important enzymes with lower acute toxicity toward Vibrio fischeri than commercial pure FeO particles.

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Multiple-shelled Fe2O3 yolk-shell particles were synthesized using the spray drying method and intended as a suitable support for the immobilization of commercial enzymes such as glucose oxidase (GOx), horseradish peroxidase (HRP), and laccase as model enzymes. Yolk-shell particles have an average diameter of 1-3 μm with pore diameters in the range of 16 to 28 nm. The maximum immobilization of GOx, HRP, and laccase resulted in the enzyme loading of 292, 307 and 398 mg per g of support, respectively. After cross-linking of immobilized laccase by glutaraldehyde, immobilization efficiency was improved from 83.5% to 90.2%. K(m) and V(max) values were 41.5 μM and 1722 μmol min(-1) per mg protein for cross-linked laccase and those for free laccase were 29.3 μM and 1890 μmol min(-1) per mg protein, respectively. The thermal stability of the enzyme was enhanced up to 18-fold upon cross-linking, and the enzyme retained 93.1% of residual activity after ten cycles of reuse. The immobilized enzyme has shown up to 32-fold higher stability than the free enzyme towards different solvents and it showed higher efficiency than free laccase in the decolorization of dyes and degradation of bisphenol A. The synthesized yolk-shell particles have 3-fold higher enzyme loading efficiency and lower acute toxicity than the commercial Fe2O3 spherical particles. Therefore, the use of unique yolk-shell structure Fe2O3 particles with multiple-shells will be promising for the immobilization of various enzymes in biotechnological applications with improved electrochemical properties. To the best of our knowledge, this is the first report on the use of one pot synthesized Fe2O3 yolk-shell structure particles for the immobilization of enzymes.