Dipeptide–Copper Hybrid Nanoparticles as Efficient Laccase Mimics for Determination and Degradation of Phenolic Pollutants and Epinephrine

The broad application of laccase mimics is notably constrained by their costly and intricate synthesis routes. For example, researchers often use peptides to coordinate with copper ions to mimic the active sites of laccases, thereby constructing laccase mimics. However, these synthetic methods are quite complex, such as requiring high temperatures, the use of organic solvents, long durations, and cumbersome procedures. In this study, we introduce a straightforward yet highly active, robust, and versatile laccase mimic known as HH-Cu, which was synthesized through a simple precipitation reaction by combining the dipeptide HH with Cu²⁺ ions in phosphate-buffered saline (PBS). By adjusting the ratio of HH to copper ions, we were able to produce the most effective organic-inorganic hybrid nanoparticles, namely, HH-Cu, which outperforms the HH-Cu nanoflowers. HH-Cu demonstrates extraordinary catalytic efficiency, with a 4.7-fold higher maximum velocity (<i>v</i> _max) and a lower Michaelis constant (<i>K</i> _m) compared to natural laccase. This nanozyme is also remarkably resilient under harsh conditions such as extreme pH levels, high temperatures, and high salinity, and it shows excellent storage stability and reusability. We successfully applied this nanozyme for the degradation and quantitative detection of various phenolic pollutants and epinephrine. HH-Cu demonstrates a markedly superior sensitivity for detecting epinephrine than laccase and offers a comparable limit of detection and a broader linear range compared to other laccase mimics. This research should lay the groundwork for ongoing efforts in the development of organic-inorganic hybrid nanozymes and provide an effective method for the simple and efficient synthesis of laccase mimics.