Recent advances in quantum dots: design principles, sensing mechanisms, and applications in food safety analysis

Quantum dots (QDs), first discovered in the 1980s, have rapidly evolved into one of the most promising classes of nanomaterials due to their exceptional optical tunability, quantum confinement effects, and surface modifiability. This review provides a structured overview of QDs starting from their historical development and fundamental properties, including size-dependent fluorescence (FL), high photostability, and surface chemistry. The synthesis and preparation methods are systematically discussed. The paper then explores key sensing mechanisms, including FL quenching, immunoassays, antibacterial action, and the toxicity profile of QDs. To improve the performance and specificity of QD-based sensors, several optimization strategies are presented, including heteroatom doping, hybridization with other nanomaterials, integration with molecularly imprinted polymers (MIPs), and the development of dual-mode FL-colorimetric systems. The practical applications of these enhanced QD sensors in food safety and environmental monitoring are highlighted, particularly for the detection of contaminants such as antibiotic residues, pesticides, and harmful gases. By combining fundamental science with applied sensor development, this review illustrates the vast potential of QDs in real-world monitoring scenarios while also addressing key challenges and future directions.