Ammonia-sensitive chitosan-based composite integrating fluorescence sensing and potential antitumor activity against thyroid cancer cells

Chitosan (CS), a natural biodegradable polymer with excellent biocompatibility and abundant modifiable functional groups, has attracted considerable attention in drug delivery and biosensing applications. In this study, a multifunctional chitosan-based fluorescent composite (CS-1) was constructed by introducing a natural product-derived fluorescent moiety, enabling NH₄⁺ sensing and cantharidin incorporation. The resulting CS-1@cantharidin composite exhibited good fluorescence stability and a sensitive response toward NH₄⁺ under physiological pH conditions (7.0), with a linear detection range of 0–7 μM and a detection limit of 0.016 μM. The composite also showed good selectivity in the presence of various physiologically relevant ions and biomolecules. Furthermore, CS-1@cantharidin reduced TPC-1 thyroid cancer cell migration and decreased PCNA mRNA expression, as demonstrated by Transwell and qPCR analyses. These results indicate that CS-1@cantharidin integrates NH₄⁺ fluorescence sensing with cantharidin-loading capability in a biocompatible chitosan-based composite, providing a potential multifunctional platform for ionic microenvironment analysis and cancer-related applications.