Fast anisotropic growth of the biomineralized zinc phosphate nanocrystals for a facile and instant construction of laccase@Zn3(PO4)2 hybrid nanoflowers

Abstract

Organic-inorganic hybrid nanoflowers (HNFs) of laccase@Zn3(PO4)2 were fabricated through a facile, simple, and rapid one-step strategy. In this process, laccase was involved in nucleation and fast anisotropic growth reactions with Zn (II) and phosphate ions. The average pore size of the prepared HNFs was 54.5 nm, and its BET-specific surface area was 59.5 m2 g−1. In comparison with the free laccase, the entrapped enzyme activity in the constructed HNFs was 86.4%. In addition, the hybrid biocatalyst displayed a maximum rate of reaction (Vmax) of 1640.2 ± 3.6 μmol min−1 with respect to the native enzyme. The constructed HNFs maintained 45.1% and 60% of the original laccase activity after 12 successive reusability cycles and 30 days of storage at 4 °C, respectively. The as-obtained HNFs demonstrated a high bioremoval percentage of Direct blue-71 (94.1%) within a 10-h-treatment at 40 °C and 15 mg l−1 of the dye concentration. The pseudo-first order and second order were the best-fitted kinetic models for the dye removal using Zn3(PO4)2 nanoflakes and the fabricated HNFs, respectively. Besides, liquid chromatography-mass spectrometry (LC-MS) revealed biotransformation of the dye into less toxic metabolites as verified by testing on some bacterial strains.