Bioinspired bimetallic metal–organic framework nanozyme with laccase-mimicking activity for detection and removal of phenolic contaminants

Laccase, despite its eco-friendly nature, faces constraints due to cost and inherent vulnerability, restricting its widespread application. Therefore, pursuing the development of a robust laccase mimetic displaying exceptional activity remains an ongoing endeavor. This research synthesized a bimetallic metal–organic framework nanozyme (Cu-Mn MOF) with enhanced laccase-mimicking activity via a one-step solvothermal method. The diverse Cu redox valence state of the nanozyme mimics the multi-copper active center of laccase, which endows Cu-Mn MOF with laccase-mimicking activity. Incorporating Mn introduces a novel metal center into the MOF, creating a catalytic microenvironment. Bimetallic Cu-Mn synergistic interplay accelerates the electron transfer rate, resulting in enhanced laccase-mimicking activity. The Michaelis constant of Cu-Mn MOF for 2,4-dichlorophenol (2,4-DP) registers at 0.080 mM, displaying remarkable stability and recyclability even under stringent conditions, thereby achieving a comprehensive surpass of laccase. Accordingly, Cu-Mn MOF was utilized to degrade phenolic compounds and design a smartphone sensing platform to facilitate portable and visual detection of phenol. Utilizing the occurrence of Cu-S coordination, which accelerates the electron transfer rate, a thiourea-enhanced Cu-Mn MOF was designed to improve the degradation rate. The limit of detection (LOD) for smartphone platform is 0.159 μM, with a linear detection range of 1–40 μM. The detection method was applied to determine the phenol in spiked samples with the spiked recoveries rate of 96.05–104.30 % and the relative standard deviations less than ± 4 %. The outcomes of these applications reveal the vast application potential of Cu-Mn MOF in environmental engineering.