DNA directed immobilization of horseradish peroxidase on phase-transitioned lysozyme modified TiO2 for efficient degradation of phenol in wastewater

In this work, TiO2 nano particle was used for two purposes: it played as a role of a solid carrier for immobilization of HRP, and meanwhile acted as a photo-catalyst itself. In this way, the loss of enzymatic activity during enzyme immobilization can be compensated by the coupling of TiO2 photo-catalysis. Then, the surface of TiO2 nanoparticles were modified by phase-transitioned lysozyme (FM) and connected with horseradish peroxidase (HRP) via a DNA helix (HRP-DNA-PTL@TiO2). The DNA double helix chain was utilized as a flexible spacer arm to keep the flexibility of the immobilized enzyme. The HRP-DNA-PTL@TiO2 showed a high recovered activity (90.52%) of the original activity of free HRP. This data is better than most reported activity recovery of immobilized enzyme. Moreover, HRP-DNA-FIFL@TiO2 can maintain high catalytic activity, stability and reusability when degrading phenol in wastewater. The phenol of 0.5 mmol.L-1 could be totally degraded within 10 min. Moreover, a visual colorimetric method for phenol concentration by HRP-DNA-PTL@TiO2 was established, and the phenol concentration of 0-0.2 mmol.L-1 can be visually detected with naked eyes. Furthermore, an enzymatic-photocatalytic synergetic effect of HRP-DNA-PTL@TiO2 is found and investigated. The efficiency of HRP-DNA-PTL@TiO2 ensures it a potential application in the wastewater treatment. (C) 2021 The Author(s). Published by Elsevier Ltd.

Automated summary

This study immobilized HRP enzyme on TiO2 nanoparticles for catalyzing phenol degradation in wastewater, achieving high catalytic activity, stability, and reusability. A visual colorimetric method for phenol concentration detection was established using HRP-DNA-PTL@TiO2, showing potential for wastewater treatment applications with its synergistic enzymatic-photocatalytic effect.