A Water-Soluble Small-Molecule Fluorescent Probe for Selective Imaging of Colorectal Cancer with High Biosafety.

Early diagnosis of colorectal cancer (CRC), a malignant tumor with high incidence and mortality rates worldwide, can significantly reduce both its incidence and mortality. Among cancer diagnostic methods, tumor fluorescence imaging provides a non-invasive approach, eliminating the need for tissue biopsy and minimizing patient discomfort. In this study, we identified a water-soluble quinolinium molecular fluorescent probe (CYI), which exhibits a dose-dependent quantum yield in PBS solution, reaching 5.96% at a concentration of 20 µM. The results demonstrated that CYI selectively enters CRC cells and maintains stable fluorescence intensity within them by specifically targeting the mitochondria and lysosomes, leading to probe accumulation and enhanced intracellular fluorescence. Importantly, toxicity assays at both the cellular and animal levels confirmed that CYI is highly biocompatible at fluorescence imaging doses, with no toxic effects observed in normal colorectal cells or organisms. This study identifies CYI as a water-soluble molecular fluorescent probe with a high biosafety profile, excellent imaging stability, and preferential uptake by CRC cells, demonstrating strong potential for early CRC screening and in vivo monitoring.