Rational design of two-photon absorbing dicyanomethylene-4H-chromene derivatives and their application in bioimaging

- A class of DCM derivatives with large 2PA cross-section at NIR range were synthesized.
- PCM was successfully applied for labelling cancer cells with minimal autofluorescence.
- PCM was successfully utilized to labelling zebrafish with deeper penetration (>300 μm).

In vitro and in vivo fluorescence imaging of cells and animals plays a significant role in studying biological systems. However, autofluorescence becomes a serious issue in vivo imaging under excitation at UV−vis wavelengths where biological molecules cause interference with the chromophore. In order to address this issue, a novel class of dicyanomethylene-4H-chromene (DCM) derivatives (PCM, PCV, BPCM and BPCV) that can be excited at ∼900 nm under two-photon excitation conditions and emit in the red wavelength region (≥600 nm) have been developed. Particularly, one of the DCM derivatives (PCM) shows several advantages, including remarkable two-photon absorption (2PA) properties in the near-infrared (NIR) region, superior photostability, large Stokes-shift and pronounced solvent-sensitive emission behavior, which is favorable for in vivo fluorescence labelling with a high signal-to-noise ratio.

A new DCM derivative (PCM) with remarkable two-photon absorption (2PA) properties was successfully applied for labelling cancer cells and zebrafish with minimal autofluorescence and deeper penetration (>300 μm).241