Simultaneous sensing of ammonia and temperatures using a dual-mode freshness indicator based on Au/Cu nanoclusters for packaged seafood.

Seafood is highly perishable and monitoring its freshness this thus an important issue. For the first time, the current study developed a dual-mode freshness indicator based on d-penicillamine capped bimetallic gold/copper nanoclusters (DPA-Au/CuNCs) as a response probe for simultaneous monitoring of ammonia and temperatures to assess seafood freshness. Results indicated that the prepared DPA-Au/CuNCs have good sensitivity toward ammonia, with a limit of detection of 0.14 ppm. The indicator as a gas sensor for ammonia vapour detection exhibited highly recognizable fluorescence colour changes and the variations from white to yellow were observed with increasing storage temperature under natural light. For confirming its practical applications, the indicator was used to simultaneously monitor ammonia and temperatures during the storage of shrimp and fish, showing good potential for practical applications in evaluating seafood freshness for the food industry.