Review of Single-Atom Nanozymes for Detection of Biomolecules, Pollutants, Microbes, and Food Additives

Single-atom nanozymes (SAzymes) have attracted growing interest for sensing applications due to their well-defined active sites and high atomic utilization. This review provides an overview of SAzyme synthesis methods, with a focus on comparing atomic layer deposition and MOF-derived routes. Beyond catalytic performance, we discuss four practical factors that are often overlooked: long-term storage stability, reproducibility, scalability, and regulatory considerations for food and environmental use. We then summarize recent progress in applying SAzymes to detect small biomolecules, environmental pollutants, and food additives. We also point out several gaps in the current literature. Most studies still test SAzymes in simple buffer systems rather than real complex samples. Selectivity is often confused with anti-interference, and systematic comparisons between SAzymes and conventional nanozymes remain scarce. Looking forward, we think future work should pay more attention to stability in complex matrices, honest assessment of selectivity, and regulatory pathways. Without addressing these issues, SAzymes will struggle to move from the bench into real-world applications.