Caspase-3-Responsive Fluorescent/Photoacoustic Imaging of Tumor Apoptosis.

Caspase-3 is an essential executor in apoptosis, and its activation has been regarded as a biomarker of cell apoptosis. The development of Caspase-3-responsive multimodal probes is a promising research prospect. Fluorescent/photoacoustic (FL/PA) imaging has attracted considerable attention due to the high sensitivity of FL as well as the high spatial resolution and penetration depth of PA. To our knowledge, there has been no tumor-targeted FL/PA probe to monitor the activity of Caspase-3 . Therefore, we developed a tumor-targeted FL/PA probe () for Caspase-3-responsive imaging of tumor apoptosis. without tumor-targeted biotin is used as a control probe. experiments indicated that is superior to because of the higher kinetic parameter of in comparison to . Cell and tumor imaging results suggested that could enter and accumulate in tumor cells with higher FL/PA signal with the help of tumor-targeted biotin. In detail, or could image apoptotic tumor cells with 4.3-fold or 3.5-fold FL enhancement and 3.4-fold or 1.5-fold PA enhancement. or could image tumor apoptosis with 2.5-fold or 1.6-fold FL enhancement and 4.1-fold or 1.9-fold PA enhancement. We envision that will be applied for FL/PA imaging of tumor apoptosis in clinical settings.