Advancements in Carbon Dot Nanozymes for Dual and Multi-Mode Biosensing of Biological and Chemical Contaminants

With the increasing frequency and growing complexity of food and environmental contaminants, there is a clear need for advanced sensing platforms that offer high sensitivity, rapid response times, and broad analytical applicability. Carbon dots (CDs), widely recognized as a novel class of nanozyme materials, have attracted significant interest due to their tunable physical and chemical properties, strong catalytic performance, advantageous optical characteristics, and excellent overall stability. Due to their multifunctional advantages, CD nanozymes are considered highly promising for developing next-generation multi-mode sensing systems. Moreover, dual- and multi-mode sensing approaches have garnered increasing interest due to their ability to provide complementary analytical data and enhance the reliability of measurements based on a single signal. Herein, this review comprehensively discusses recent progress in CD nanozyme-enabled multi-mode systems designed to detect biological and chemical contaminants. It begins by explaining the catalytic mechanisms and structure-activity relationships that govern the performance of CD nanozymes. Subsequently, it organizes recent advances in target-specific sensing applications, focusing on the detection of food pollutants. Special attention is given to multimode sensing approaches that combine colorimetric, fluorometric, electrochemical, or other signal-conversion methods to enhance sensitivity, selectivity, and analytical reliability. Finally, current limitations and future directions are discussed.