Synthesis of phenylalanine/manganese-copper supramolecular sheets with laccase-like activity for the detection of phenolic pollutants

Enzyme mimics with laccase-like activity showing excellent stability and tolerance have attracted extensive interest in phenolic pollutants treatment. Herein, we presented a mild and convenient strategy for the preparation of laccase-like sheets (denoted as Mn-F-Cu) inspired by the supramolecular self-assembly of the transition metals manganese, copper, and L-phenylalanine (F) under room temperature, alkaline conditions. The Mn-F-Cu sheets perform a better substrate affinity (Michaelis constant, Km = 0.65 mM) and a higher reaction rate (Vmax = 3.98 × 10−3 mM·min−1) at 25 °C, pH 6.8 compared to natural laccase (Km = 1.08 mM; Vmax = 6.93 × 10−6 mM·min−1). Besides, the catalytic stability data show they also exhibit good tolerance under alkaline pH (pH 8–10) and high temperature (70–90 °C). More importantly, the prepared Mn-F-Cu material shows a relatively better sensitivity in detecting phenolic pollutants 2,4-DP and catechol than other laccase mimics mentioned in the literature, with a detection limit of 2.41 μM and 3.49 μM, respectively(R2 > 0.99). Therefore, Mn-F-Cu sheets show great potential to replace natural laccase for the detection and treatment of phenolic pollutants in harsh environments.