Cu₂(OH)₃NO₃ nanozyme sensor array for the discrimination of multiple sulfides in food

In the food industry, sulfides are commonly used as preservatives and flavor regulators. However, long-term excessive intake of sulfides can lead to serious health problems. Therefore, developing efficient sulfide detection methods is particularly important. Here, we have effectively synthesized a novel bifunctional copper hydroxide nitrate (Cu₂(OH)₃NO₃) nanozyme with outstanding peroxidase-like and laccase-like behaviors in basic deep eutectic solvents (DES). Because the various types of sulfides have diverse regulatory effects on the two catalytic behaviors of Cu₂(OH)₃NO₃, a two channel nanozyme sensor array based on the peroxidase-like and laccase-like behaviors of Cu₂(OH)₃NO₃ was constructed and successfully used for the identification of six kinds of sulfides (Na₂S, Na₂S₂O₃, Na₂SO₃, Na₂SO₄, NaHSO₃, and Na₂S₂O₈). Remarkably, the sensor array has achieved successful discrimination among six sulfides present in wine, egg, and milk samples. Finally, the sensor array has successfully distinguished and differentiated three actual samples (wine, egg, and milk). This study is of great significance in promoting the efficient construction of array units and improving the effective identification of sulfides in complex food samples.