Synthesis of functional near infrared pyrrolopyrrole cyanine dyes for optical and photoacoustic imaging

Fluorescence lifetime and photoacoustic imaging (PAI) provide attractive strategies for in vivo molecular imaging in the near infrared (NIR) region. Pyrrolopyrrole cyanine (PPCy) dyes are promising molecules for these applications. In this study, we synthesized a chloro-functionalized non-fluorescent dye with high absorption coefficient suitable for PAI. Upon complexation with boron, the dye becomes highly fluorescent with lifetime of 3.6 ns, which is longer than most cyanine dyes commonly used for NIR optical imaging. The potential to use the non-fluorescent or fluorescent analogs of PPCy for fluorescence or photoacoustic imaging provides a versatile approach to image molecular processes and physiological events by these methods.