Synthesis and application of near-infrared dyes based on sulfur-substituted dicyanomethylene-4H-chromene and diarylethene

Abstract

Four novel compounds (S-DCM-1O, S-DCM-2O, S-DCM-3O, and S-DCM-4O) based on sulfur-substituted dicyanomethylene-4H-chromene (S-DCM) and diarylethene were synthesized. The detailed investigations on the fluorescence spectra, absorption spectra, and time-dependent density functional theory calculations (DFT/TD-DFT) were presented. The encapsulation of mPEG₂₀₀₀-DSPE effectively increased the solubility of all the as-prepared samples. The results of TEM showed that the nanoparticles had a good dispersion coefficient. All the nanomaterials (S-DCM-1O@PEG, S-DCM-2O@PEG, S-DCM-3O@PEG, and S-DCM-4O@PEG) exhibited near-infrared emission (650–900 nm) and thus reduced light damage and light scattering for cell imaging in biological applications. Furthermore, PLL (poly-L-lysine hydrobromide) was used to modify the surface of nanoparticles to facilitate easy uptake by A549 cells by changing their electronegativity. The results suggested that S-DCM-2O@PEG@PLL was a highly suitable candidate for cell imaging because of its low toxicity and excellent biocompatibility.