Nanoporous Phyllosilicate Assemblies for Enzyme Immobilization

Physical/chemical adsorption is well-known as a facile and effective method for enzyme immobilization, while ideal adsorbents with a high structural stability, high loading capacity, and low leaching ratio are still under exploration. In this study, nanoporous assemblies of two-dimensional (2D) copper phyllosilicate (L-CuSiO₃) are prepared as an adsorbent to immobilize horseradish peroxidase (HRP) for phenol-containing wastewater treatment. Specifically, the robust chemical bonds of Si-O-Si and Si-O-Cu in L-CuSiO₃ ensure its superior structural stability; the well-developed porous structure endows L-CuSiO₃ assemblies with a high specific surface area of 611.7 cm³ g^-1, which enables a fast and high enzyme loading of 140 mg g^-1 within 4 h, and the well-distributed Cu(II) ions ensure the stable attachment of enzyme through Cu(II)-arginine (in HRP) coordination with a leaching ratio less than 10%. Meanwhile, the scaling assembly of L-CuSiO₃ renders the resultant biocatalyst (HRP-loaded L-CuSiO₃ assemblies) ease-of-recycling performance. Given the above features, the HRP-loaded L-CuSiO₃ assemblies exhibit a better stability and 2-fold higher activity by contrast with HRP adsorbed on conventional mesoporous SiO₂ and SiO₂ nanoparticles, and it also acted as an efficient bioreactor in the application of catalytical removal of phenol pollutants from wastewater. Our L-CuSiO₃ assemblies show great potential in immobilization of enzymes for industrial biocatalysis.