Reengineering Cyanine Dyes via Borondifluoro Indolenine: A Tunable Platform for Wash-Free Imaging and Responsive Biosensing
Zixuan Zhan, Jifa Zhang, Tianruo Shen, Jie Li, Li Chai, Lili Pan, Haihui Yang, Tianyou Liu, Xiaogang Liu, Wuyu Mao
Abstract
Fluorescent probes are essential tools for visualizing biological processes, yet conventional cyanine dyes suffer from limited structural flexibility, poor photostability, and weak compatibility with wash-free imaging. Here, we introduce a modular, neutral BF 2 -bridged cyanine (BCy) platform by re-engineering the indolium scaffold with a borondifluoro indolenine (BFI) fragment. BCy dyes exhibit high brightness (up to 12.4 × 10 4 M –1 cm –1 ), robust photostability, and emissions spanning 588–837 nm. The tunable BFI moiety enables the construction of wash-free, far-red/NIR probes for the plasma membrane, lipid droplets, mitochondria, and lysosomes as well as pH- and H 2 O 2 -responsive sensors. These probes support high-contrast multicolor and STED imaging, as well as dynamic organelle tracking in live cells and a mouse model of liver injury. This work establishes BF 2 -cyanines as robust scaffolds for next-generation fluorophores in advanced bioimaging and biomedical diagnostics.