Amine oxidase@Li-CaCu2O3 based electrochemical biosensor for the detection of tyramine in marine fishes and crab

Abstract

Quality analyses of seafood ensure consumer safety, maintain public health, and support the sustainability of the fishing industry. As seafood is a perishable commodity, it is particularly susceptible to contamination by pathogens, biotoxins, and spoilage. Elevated levels of Tyramine (TA) in seafood indicate its quality deterioration through spoilage due to ageing, improper storage or poor handling. Here, we report a novel enzymatic biosensor integrating Amine oxidase (AoX) enzyme with Li-doped CaCu₂O₃ nanoflakes for the quantification of TA in various marine fish species. The AoX enzyme has been covalently immobilized onto the Li-CaCu₂O₃/glassy carbon electrode (GCE) via the cross-linker glutaraldehyde. The AoX@Li-CaCu₂O₃/GCE exhibited excellent electrocatalytic activity and high sensitivity towards the TA detection. High specificity of the AoX enzyme, flake-like morphology, mixed-valence copper centres (Cu²⁺/Cu¹⁺) and improved electroactive surface area of Li-CaCu₂O₃ provide abundant active sites, resulting in an improved redox behaviour with higher current response. Further, the sensor efficiently detected TA over a wide concentration range of 0.15 to 250 μM, with the lowest detection limit and limit of quantification of 0.11 μM and 0.37 μM respectively. In addition, the real-time applicability of the AoX@Li-CaCu₂O₃/GCE has been validated by quantifying TA in marine fishes such as trevally, silver, lady, mullet, anchovy, pipe, cobia fish and sea crab. The obtained results have been cross-validated by high pressure liquid chromatographic analysis. Further, the sensor showed acceptable relative standard deviation (1.02-1.96%) and recovery values (98.1 – 101.5%). In conclusion, the fabricated AoX@Li-CaCu₂O₃/GCE could be useful for rapid and precise sea food analyses.