Immobilized lignin peroxidase on Fe3O4@SiO2@polydopamine nanoparticles for degradation of organic pollutants.

Lignin peroxidase (LiP) was obtained from Pichia methanolica through heterologous expression. LiP was extracted, purified, and immobilized on Fe3O4@SiO2@polydopamine (PDA) nanoparticles to acquire immobilized LiP. The optimal preparation conditions for immobilized LiP were investigated. Results showed that the immobilization efficiency of immobilized LiP reached 56.37% when the enzyme amount, PDA concentration, and immobilization time were 12 mg, 1.6 mg/mL, and 12 h, respectively. Compared with free LiP, the immobilized LiP showed good thermal stability and storage stability and improved pH tolerance. It also retained more than 30% of its initial activity after 8 cycles, demonstrating its improved reusability. The immobilized LiP demonstrated efficacy of reaction of 100%, 100%, 100%, 100%, 79%, 73%, and 65% for tetracycline, dibutyl phthalate, 5-chlorophenol, phenol, phenanthrene, fluoranthene, and benzo(a)pyrene, respectively, while the inactivated immobilized LiP only adsorbed <25% of phenanthrene and fluoranthene. The dissipation of organic pollutants was a combination of degradation and adsorption, with the former playing a more important role.