Microwave-Assisted Growth of Laccase Mimetic Copper Oxide Nanozyme for Biosensing Applications

Abstract

Natural enzymes are highly efficient macromolecular biocatalysts that can selectively catalyze biological reactions with high activity and substrate specificity under optimum conditions. However, natural enzymes suffer from several inherent drawbacks, such as susceptibility to denaturation, laborious preparation, difficulties in recycling, and high cost, significantly constraining their practical applications. Among the natural enzymes, laccases are an important class of oxidative enzymes belonging to the family of multicopper oxidases, which couple the monoelectronic oxidation of its substrates with the reduction of dioxygen into water. This enzyme exhibits great potential in several applications, including dye bleaching, anticancer treatment, wastewater treatment, soil bioremediation, and biocatalysts for organic synthesis. Nevertheless, the poor stability under harsh environmental conditions, high cost, and non-recyclability of the native laccase enzyme seriously restrict its practical applications. In this thesis work, we have explored the laccase like activity of Cu2O nanosphere, fabricated using one pot polyol-based microwave-assisted method. The as-synthesized Cu2O nanosphere exhibited outstanding laccase-like activity with a Michaelis−Menten rate constant (Km) value of 0.2 mM for 2,4-dichlorophenol as a substrate, which is noticeably smaller than previously reported nanozymes as well as natural laccase. The laccase-like oxidase property of the nanozyme was exploited in the effective and sensitive detection of biorelevant catechol-bearing molecules such as epinephrine and dopamine. Furthermore, a platform has been developed for the sensitive detection of Acetylcholinesterase using the Cu2O nanozyme as a probe. In general, this robust and recyclable laccase mimetic nanozyme holds great potential for biosensing, sustainable environmental protection, and biotechnology applications.