Smartphone-Integrated Laccase-like Nanozyme Colorimetric Sensors for Food Quality and Environmental Analysis: Mechanisms, Materials Design, and Analytical Challenges.

The growing demand for portable, rapid, and cost-effective diagnostic methods has driven the advancement of smartphone-assisted colorimetric sensors. Among the various emerging substrates, colorimetric sensors based on laccase-like nanozymes have garnered significant interest due to their low cost, high stability, tunable catalytic properties, and environmentally friendly catalytic mechanisms. These nanozymes catalyze the oxidation of both phenolic and non-phenolic substrates by mediating a four-electron reduction of oxygen to water, without generating harmful hydrogen peroxide (H2O2). Significantly, they have developed a systematic design approach characterized by well-defined structure-activity relationships and well-established catalytic mechanisms. When combined with the advanced imaging and communication capabilities of smartphones, these nanozyme-enabled systems offer promising alternatives to traditional laboratory-based techniques. Herein, this study offers a critical analysis of recent advancements in smartphone-integrated colorimetric sensors that utilize laccase-like nanozymes. It specifically focuses on catalytic principles, the design of nanozyme materials, sensing methodologies, and their analytical applications. Significant emphasis is placed on various types of laccase-like materials and their potential uses in food safety and environmental analysis over the last three years. Additionally, structural optimization, electronic modulation, and bioinspired active site modifications aimed at enhancing enzyme-like activity have been explored. Finally, current challenges and future perspectives are critically discussed.