When the enzyme meets the nanowire
Traditional supports immobilized enzymes have shown the ability to increase thermal/chemical stability and reduce mass transfer limitation, but reduced apparent activity mainly due to unfavorable enzyme-carrier interactions which further lead to denaturation and deactivation of the enzymes. Inorganic nanomaterials have emerged as competitive carriers for enzyme immobilization owing to the fascinating properties related to the reduced dimensions of inorganic materials. The bio-active inorganic nanocarriers can dramatically enhance apparent specific enzyme activity in which enzyme-carrier interaction is effectively modulated. This kind of nanobiocatalyst is still beset by the worsening of other catalytic features. For instance, immobilized enzymes in most cases are dispersed unorderly at the levels of both nanoparticle surface and three-dimensional spatial arrangement in a partially closed system, which is adverse to the promotion of diffusion and partition problems. In addition, conventional method assesses specific activity of immobilized enzyme based on the amount of enzyme immobilized on the carrier, which might not be suitable for the nanobiocatalyst as bulk carriers are still needed in most case for recovery them from reaction solution. In this context, the reported nanobiocatalysts with high specific enzyme activity actually have unsatisfactory overall catalytic activity due to the presence of large “dead volume” which do not contribute to the biocatalysis process. Natural nanostructures in living system offer exquisite architecture for enzymes to mediate various biochemical reactions in a very efficient way. Inspired by this, Fan et al fabricated the laccase-Cu2O nanowire mesocrystal hybrid materials which developed with superior catalytic activity that highly resembles the metal ions activation and the well-organized spatial structure of natural rough endoplasmic reticulum. The enzyme and nanobiocatalyst activities of the obtained hybrid material exhibited about 10-fold and 2.2-fold increase than free enzyme respectively, surpassing the currently-available nanobiocatalysts. The comprehensive catalytic performance of the hybrid materials has been further demonstrated using a prototype continuous-flow reactor for the bioremediation of 2,4-dichlorophenol contaminated water, showing high degradation efficiency and remarkable reusability. This kind of new nanobiocatalysts are expected to fulfill high-efficient biocatalysis for diverse applications in biotechnology, biosensing and environmental remediation.