In Vivo Photoactivation Without “Light”: Use of Cherenkov Radiation to Overcome the Penetration Limit of Light
The poor tissue penetration of visible light has been a major barrier for optical imaging, photoactivatable conversions, and photodynamic therapy for in vivo targets with depths beyond 10 mm. In this report, as a proof-of-concept, we demonstrated that a positron emission tomography (PET) radiotracer, 2-deoxy-2-[18F]fluoro-d-glucose (18FDG), could be used as an alternative light source for photoactivation.
We utilized 18FDG, which is a metabolic activity-based PET probe, as a source of light to photoactivate caged luciferin in a breast cancer animal model expressing luciferase.
Bioluminescence produced from luciferin allowed for the real-time monitoring of Cherenkov radiation-promoted uncaging of the substrate.
The proposed method may provide a very important option for in vivo photoactivation, in particular for activation of photosensitizers for photodynamic therapy and eventually for combining radioisotope therapy and photodynamic therapy.
Key wordsCherenkov radiation Bioluminescence Photoactivation Caged luciferin