||Development of photostabilized asymmetrical cyanine dyes for in vivo photoacoustic imaging of tumors.
Onoe, Satoru ,
Temma, Takashi ,
Kanazaki, Kengo ,
Ono, MasahiroSaji, Hideo
Journal of biomedical optics
2015-09 , Society of Photo-Optical Instrumentation Engineers(SPIE)
Photoacoustic imaging (PAI) contributes to tumor diagnosis through the use of PAI probes that effectively accumulate in tumors. Previously, we developed a symmetrical cyanine dye, IC7-1-Bu, which showed high potential as a PAI probe because of its high tumor targeting ability and sufficient in vivo PA signal. However, IC7-1-Bu lacks photostability for multiple laser irradiations, so we developed stabilized PAI probes using IC7-1-Bu as a lead compound. We focused on the effect of singlet oxygen (1O2) generated by excited PAI probes on probe degeneration. We introduced a triplet-state quencher (TSQ) moiety into IC7-1-Bu to quench 1O2 generation and designed three IC-n-T derivatives with different linker lengths (n indicates linker length). The IC-n-T derivatives emitted in vitro PA signals that were comparable to IC7-1-Bu and significantly reduced 1O2 generation while showing improved photostability against multiple irradiations. Of the three derivatives evaluated, IC-5-T accumulated in tumors effectively to allow clear PAI of tumors in vivo. Furthermore, the photostability of IC-5-T was 1.5-fold higher than that of IC7-1-Bu in in vivo sequential PAI. These results suggest that IC-5-T is a potential PAI probe for in vivo sequential tumor imaging.