Design of a Porous and Stable Sodium Alginate–Silica Composite for Dual Fluorescent Detection of Fe ³⁺ and 5‐Fu in Colorectal Cancer Treatment

In this study, a multifunctional fluorescent sensing platform was constructed via stepwise functional modification. The platform is based on a cobalt (II)-containing metal-organic framework (MOF) and was successively modified with donor-acceptor Stenhouse adducts (DASA), a natural product-derived compound 1, and 3-aminopropyltrimethoxysilane (APTMS), yielding the composite material 1-DASA-APTMS@CP1. This material was further employed for the loading and selective detection of the anticancer model drug 5-FU (1-DASA-ATPMS@CP1@5-Fu). Fluorescence sensing experiments revealed that 1-DASA-APTMS@CP1 exhibited excellent selectivity and sensitivity toward Fe³⁺ and 5-FU among a series of metal ions and antibiotics. The calculated Stern-Volmer quenching constants (Ksv) were 1.38 × 10⁴ M^-1 for Fe³⁺ and 1.77 × 10⁴ M^-1 for 5-FU, with corresponding detection limits of 6.04 and 4.71 μM, respectively. Furthermore, in vitro experiments using human colorectal cancer HCT116 cells confirmed the therapeutic potential of the platform. The 1-DASA-APTMS@CP1@5-Fu system significantly enhanced apoptosis induction, as demonstrated by CCK-8 assays, qPCR, and western blot analysis, which showed upregulation of the proapoptotic protein Bax. This study provides a novel strategy and experimental basis for colorectal cancer targeted drug delivery and fluorescence-guided cancer theranostics.