We have prepared high-performance functional aromatic polyamides with sensory pendant groups toward amines. These polymers are colourless. The pendant groups have bromonaphthalimide motifs that react with amines rendering coloured arylamines by nucleophilic aromatic substitution of the halide. Thus, these materials are colorimetric sensors toward amines. In the interest of saving costs, while having a sensory material with a high specific surface, cotton fabrics were coated, in order to render coated fibres as smart colorimetric labels toward amines. Moreover, as fish spoilage by microorganism increases the biogenic amines in food, we have applied the smart labels to visually follow the food spoilage. Also, a picture taken to the films allowed to obtain, in seconds, the digital colour definition parameters (RGB) that were correlated with the results of expensive and time-consuming conventional techniques used to obtain relevant food quality data, such as total amine concentration (treatment of the sample and HPLC), colony-forming unit (microbiological assays), total volatile basic nitrogen (TVB-N), and organoleptic test (sensory test). The smart labels are inexpensive, granting in seconds the visual qualitative evaluation of the food quality, or even quantitative, and they comply with the European food contact materials regulation.
