Advances in optical devices for the detection of contaminants in food and water

The detection of water and food contaminants is contributing to reach the Global Goals and the 2030 Agenda for Sustainable Development (especially Goal 2 "Zero hunger" and Goal 6 "Clean water and sanitation": ensure availability and sustainable management of water and sanitation for all). The widespread presence of contaminants has created an urgent need for analytical tools that are sensitive, specific, accurate, rapid, and easy-to-use to support legislative efforts and enable early warnings. Optical biosensors have emerged as powerful alternatives to traditional methods, which are often time-consuming and labor-intensive. Herein, we review the recent advances in the development of biosensors based on several optical techniques for the detection of food and water contaminants. In our excursus, all the main classes of biological and biomimetic recognition elements are presented ranging from traditional antibodies and molecularly imprinted polymers to DNAzyme and nanobodies. Through a critical analysis of the latest optical biosensor innovations, we explore their current limitations and potential, emphasizing the need to transition these strategies from research to practical applications. This work highlights the synergy of sensing mechanisms, nanomaterials, and technologies in creating advanced optical devices that are cost-effective, miniaturized, accurate, multi-parameter, and integrated, with the goal of bridging the gap between laboratory research and market-ready solutions.