In Vivo Near-Infrared Fluorescence and Photoacoustic Dual-Modal Imaging of Endogenous Alkaline Phosphatase.

Alkaline phosphatase (ALP) is distributed widely in living organisms and is an important biomarker closely related to many physiological and pathological processes. However, in vivo real-time detection of ALP remains a significant challenge. Herein, we developed a turn-on molecular probe (denoted as LET-3) to visualize ALP activity in tumor tissues through near-infrared fluorescence (NIRF) and photoacoustic (PA) dual-modal imaging. LET-3, composed of NIR hemicyanine dye (LET-CyOH) and a phosphate moiety, showed a 23-fold NIRF enhancement at 730 nm and 27-fold PA enhancement at 710 nm upon activation by ALP. More importantly, both in vitro and in vivo diagnostic experiments indicated that LET-3 has a high sensitivity and good selectivity for ALP. These findings provide a promising strategy for in vivo ALP detection using NIRF and PA dual-channel turn-on probes.