Silk-based films with pH sensors can be obtained by covalently grafting a neutral red dye onto silk fibroin through a Mannich reaction. These halochromic films, manufactured from regenerated fibroin, respond with high sensitivity, reversibility, and reusability to pH variations over a wide range. Color changes are monitored by spectrophotometry and image analysis with smartphones, enabling accessible and accurate detection. These sensors can also detect volatile ammonia, making them suitable for monitoring the freshness of seafood products. The objective of this initiative is to develop sensors that are both sustainable and biodegradable, with applications in real-time environmental, biomedical, and food safety monitoring.
