Efficient biocatalytic removal and algal detoxification of Direct Blue-15 by the hierarchically structured, high-performance, and recyclable laccase@yttrium phosphate hybrid nanostructures.

From the environmental point of view, azo dye industrial effluent is a major public health concern due to its toxic, carcinogenic, and teratogenic characteristics. On the other hand, using enzyme-based technologies offers a promising systematic and controllable method for removing synthetic dyes from wastewater. In the present study, yttrium (Y) phosphate was applied for the synthesis of hybrid nanoparticles (HNPs) consisting of laccase as the green catalyst. When the association of HNPs was fixed by glutaraldehyde (GA), three-dimensional cubic structures with the regular arrangement were provided. GA increased the reusability of the fabricated hybrid nanostructures (HNSs) up to 32 successive cycles. About 85% of Direct Blue-15 was removed after a 4 h-treatment using laccase@YPO•HNPs and laccase@GA@YPO•HNSs. The azo dye removal data were well-fitted with a pseudo-second-order model for both types of the prepared HNSs. For the model freshwater green alga Raphidocelis subcapitata, the half maximal effective concentration (EC) of the dye decreased 10- and 100-fold after the removal with laccase@YPO•HNPs and laccase@GA@YPO•HNSs, respectively. GA-treated HNSs (250 U L) inhibited the biofilm formation by approximately 78%, 82%, and 79% for Escherichia coli, Staphylococcus aureus, and Bacillus subtilis, respectively. Thus, the fabricated laccase@GA@YPO•HNSs could be presented as a novel, efficient, and recyclable heterogeneous biocatalyst for wastewater treatment and clean-up.