Dual-signal fluorescent test strips for spoilage sensing of packaged seafood: Visual monitoring of volatile basic nitrogens

With the food safety issues abounding, exploring reliable and efficient methods for evaluating food safety is crucial. Herein, a ratiometric test strip was proposed by using green-yellow fluorescent D-penicillamine capped silver nanocluster (DPA-AgNCs) as indicator and red-emitting bimetallic gold/silver nanoclusters (AuAgNCs) as an internal reference, providing a real-time and visual monitoring system for food freshness. Results showed that the as-prepared DPA-AgNCs displayed an excellent response and good sensitivity for volatile basic nitrogens (VBNs), with a limit of detection (LOD) of 0.51 mu M and 0.08 ppm for spermidine and ammonia hydroxide, respectively. Subsequently, a ratiometric test strip was developed to visually monitor ammonia vapour, dis-playing an obvious fluorescence colour variation from mustard to deep-red. Moreover, the presented ratiometric test strip was successfully applied for non-contact and visual evaluating and monitoring VBNs in the shrimp sample, showing high potential for in-situ monitoring.

Automated summary

Exploring reliable and efficient methods for evaluating food safety is crucial due to the food safety issues. In this study, a ratiometric test strip using D-penicillamine capped silver nanoclusters (DPA-AgNCs) and bimetallic gold/silver nanoclusters (AuAgNCs) was proposed as a real-time and visual monitoring system for food freshness. The developed test strip showed good response and sensitivity for volatile basic nitrogens (VBNs), with a limit of detection (LOD) of 0.51 mu M and 0.08 ppm for spermidine and ammonia hydroxide, respectively. It was successfully applied for non-contact and visual evaluating and monitoring VBNs in shrimp samples.