A series of silane-modified rhodamine dyes for near-IR biological fluorescence imaging of Hela cells and A549 lung cancer cells: Synthesis and sensing behavior towards ions, amino acids and hypocholorous acid.

HClO is recognized as an indicator for phagocytosis and inflammatory response. Excess HClO ruptures lysosomes and leads to cell apoptosis, which has been proposed as a cure for cancer treatment. As a consequence, the real-time and in situ cell imaging for HClO is highly appealed in the field of anticancer pharmacy. In this work, a series of silane-modified rhodamine fluorescers with various functional groups were designed, hoping to find a fluorescer with near IR emission for bio-imaging in live cells, along with unique sensing response towards ClO− over competing species. These silane-modified rhodamine fluorescers were carefully characterized, their photophysical parameters and responses towards ClO− and competing species were compared systematically. An optimal probe showed emission quantum yield of 0.26 with emission wavelength at 681 nm. Emission "turn-on" effect was observed, with calibration equation of F = 0.720*[ClO−]2+40.047*[ClO−]+54.982, R2 = 0.999, and the limit of detection (LOD) was calculated as 0.03 μM. Corresponding sensing mechanism was revealed as an HClO-mediated cyclization reaction. Fluorescence imaging for Hela cells and A549 lung cancer cells was performed. The lysosome-targetable feature was confirmed. • A series of silane-modified rhodamine fluorescers with near IR emission for bio-imaging in live cells were reported. • An optimal probe showed emission quantum yield of 0.26 with emission wavelength at 681 nm. • Sensing calibration equation was a non-linear one and the limit of detection (LOD) was calculated as 0.03 μM. • Sensing mechanism was revealed as an HClO-mediated cyclization reaction. [ABSTRACT FROM AUTHOR]