Industrial applications of immobilized nano-biocatalysts.

Immobilized enzyme-based catalytic constructs could greatly improve various industrial processes due to their extraordinary catalytic activity and reaction specificity. In recent decades, nano-enzymes, defined as enzyme immobilized on nanomaterials, gained popularity for the enzymes' improved stability, reusability, and ease of separation from the biocatalytic process. Thus, enzymes can be strategically incorporated into nanostructured materials to engineer nano-enzymes, such as nanoporous particles, nanofibers, nanoflowers, nanogels, nanomembranes, metal-organic frameworks, multi-walled or single-walled carbon nanotubes, and nanoparticles with tuned shape and size. Surface-area-to-volume ratio, pore-volume, chemical compositions, electrical charge or conductivity of nanomaterials, protein charge, hydrophobicity, and amino acid composition on protein surface play fundamental roles in the nano-enzyme preparation and catalytic properties. With proper understanding, the optimization of the above-mentioned factors will lead to favorable micro-environments for biocatalysts of industrial relevance. Thus, the application of nano-enzymes promise to further strengthen the advances in catalysis, biotransformation, biosensing, and biomarker discovery. Herein, this review article spotlights recent progress in nano-enzyme development and their possible implementation in different areas, including biomedicine, biosensors, bioremediation of industrial pollutants, biofuel production, textile, leather, detergent, food industries and antifouling.

Improved features of a highly stable protease from Penaeus vannamei by immobilization on glutaraldehyde activated graphene oxide nanosheets.

In this study, we report the synthesis of graphene oxide nanosheets (GON) by a modified Hummers method. Then, a protease purified from the Penaeus vannamei shrimp was immobilized on the GON activated with glutaraldehyde. Several techniques such as SEM, DLS and FTIR were applied to characterize the different nano-structures at the different levels. The immobilization of the protease on the GON activated with glutaraldehyde did not affect the optimum pH, but significantly improved thermal stability and stability at extreme pH values, as well as activity at 90 °C. After 24 h of incubation at 90 °C, the free enzyme retained less than 10% of the activity, while the immobilized enzyme kept more than 90% of its original activity. The apparent Km and Vmax for Penaeus vannamei protease remained fairly similar after immobilization, a very relevant data considering the large size of the substrate (casein).In the hydrolysis of casein at 70 °C and in the presence of 2 M urea, the immobilized enzyme exhibited a higher activity than the free enzyme. The results indicate that the immobilization of the enzyme Penaeus vannamei protease on GON activated with glutaraldehyde increases its already high stability against environmental stresses and makes it suitable for biotechnological and industrial applications.

Penaeus vannamei protease stabilizing process of ZnS nanoparticles.

The protease enzyme purified from the Penaeus vannamei shrimp has unique properties, so improving the stability of this enzyme can improve their practical applications. In this study, ZnS nanoparticles, which have special properties for enzyme immobilization, were synthesized using a chemical precipitation method, and Penaeus vannamei protease was successfully immobilized on them. The size, structure, and morphology of the ZnS nanoparticles, and the immobilization of the protease were studied, using Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FT-IR) spectroscopy, UV-Vis spectroscopy and Dynamic Light Scattering (DLS) analysis. We show that the immobilized enzyme has improved functionality at high temperatures, extreme pH conditions (pH3 and 12), and during storage. Immobilization increased the optimum temperature range of the enzyme, but did not change the pH optimum, which remained at pH7. Immobilization of P. vannamei protease enzyme increased the Km and decreased kcat/Km. These results indicate that P. vannamei protease immobilized on ZnS nanoparticles, has improved properties due to its high stability and unique properties, can be used for biotechnology applications.