• Open Access

Ratiometric Activatable Cell-Penetrating Peptides Provide Rapid In Vivo Readout of Thrombin Activation


  • The authors would like to thank P. Arcaira, Q. Xiong, and L. Gross. This work was funded by the NIH R01CA158448 to R.Y.T., ICMIC-NCI P50-CA128346 career development grant to E.N.S., and the American Asthma Foundation.


original image

In real time: Thrombin activation in vivo can be imaged in real time with ratiometric activatable cell penetrating peptides (RACPPs). RACPPs are designed to combine 1) dual-emission ratioing, 2) far red to infrared wavelengths for in vivo mammalian imaging, and 3) cleavage-dependent spatial localization. The most advanced RACPP uses norleucine (Nle)-TPRSFL as a linker that increases sensitivity to thrombin by about 90-fold (see figure).