Optical Properties of Laccases and Their Use for Phenolic Compound Detection and Quantification: A Brief Review

Phenolic compounds (PheCs) are particularly relevant in many different frameworks due to their pro-oxidant and antioxidant activities. In fact, on the one hand, they are considered very dangerous pro-oxidant agents that can be present in the environment as pollutants in wastewater and soil from different industrial and agricultural industries. On the other hand, the antioxidant influence of PheCs available in natural products (including foods) is nowadays considered essential for preserving human health. Conventional techniques for detecting PheCs present some disadvantages, such as requiring expensive instrumentation and expert users and not allowing in situ measurements. This is the reason why there is a high interest in the development of simple, sensitive, specific, and accurate sensing methods for PheCs. Enzymes are often used for this purpose, and laccases with unique optical properties are adopted as bio-elements for sensing schemes. The present paper aims to revise the optical properties of laccases and their use for developing PheC detection and quantification methods used in different fields such as environment monitoring, food characterization and medical applications. In particular, the results offered by UV, visible and infrared absorption, fluorescence, Raman, and surface-enhanced Raman spectroscopy (SERS) have been considered. The enzymatic biosensing devices developed using the related optical signals have been reported, and a comparison of their performances has carried out. A brief description of the main characteristics of laccase and phenols is also given.