CRISPR/Cas-Based Biosensing Strategies for Non-Nucleic Acid Contaminants in Food Safety: Status, Challenges, and Perspectives

Non-nucleic acid targets (non-NATs), such as heavy metals, toxins, and pesticide residues, pose critical threats to food safety. Although CRISPR/Cas systems were initially developed for nucleic acid detection, recent advances have enabled their adaptation to non-NATs analysis by transducing target recognition into nucleic acid signals. Unlike previous reviews categorized by target type, this work establishes a mechanism-centric framework, systematically classifying non-NAT-to-nucleic acid signal conversion methodologies into three paradigms: (1) aptamer-based systems, (2) catalytic nucleic acid-based methods (e.g., DNAzymes), and (3) protein-mediated strategies (e.g., antibodies, transcription factors). When integrated with CRISPR/Cas, these systems achieve rapid, sensitive detection at picomolar (pM) levels without relying on chromatographic or spectroscopic instruments. Furthermore, we critically discuss challenges, including the limited diversity of recognition elements, inefficient signal conversion, and inflexible signal outputs, proposing solutions including synthetic-biology-driven bioreceptor design and artificial-intelligence-based data analysis. By bridging mechanistic principles with applications in complex food matrices, this review provides actionable insights to advance CRISPR-based tools for rapid, on-site, food safety monitoring.