Upcycled sericin/coronene/CMC paper: dual-mode colorimetric and LDI-MS histamine detection for fish freshness...

This study presents a dual-mode platform for detecting histamine, a critical biomarker of fish spoilage. We engineered filter paper with a hydrogel made from upcycled sericin and carboxymethyl cellulose, which incorporates coronene. This design enables both rapid colorimetric screening and sensitive laser desorption/ionization mass spectrometry (LDI-MS) detection. Co-immobilized diamine oxidase, horseradish peroxidase, and a pH indicator produce a visible color change proportional to the concentration of histamine in the range of 0-4 mg/g. It was determined that coronene enhances histamine ionization, which enables confirmatory LDI-MS detection with high sensitivity (LOD = 0.003 mg/g). The sensor's linear range effectively covers the critical fish safety threshold of 0.4 mg/g, and it demonstrates high selectivity. We validated the sensor using real fish samples and found that this integrated approach provides a practical and sustainable solution for monitoring fish spoilage.