Photodynamic therapy (
PDT) is an innovative method for
cancer treatment that involves the administration of a
photosensitizing agent followed by exposure to visible light. An appreciable amount of a particular light source is a key to activate
photosensitizers in
PDT. However, the external excitation light source is a problem for clinical application because of the limitation of tissue-penetrating properties. Additionally, the wavelength of
laser emission should match the absorption wavelength of each
photosensitizer for efficient generation of
reactive oxygen species and cell killing. In this study,
Renilla luciferase-immobilized quantum dots-655 (QD-RLuc8) was used for bioluminescence resonance energy transfer (BRET)-mediated
PDT to resolve these problems. The bioluminescent QD-RLuc8 conjugate exhibits self-illumination at 655 nm after
coelenterazine addition, which can activate the
photosensitizer,
Foscan(®)-loaded
micelles for
PDT. Our results show that BRET-mediated
PDT by QD-RLuc8 plus
coelenterazine (20 μg/mL) successfully generated
reactive oxygen species (40.8%), killed ~ 50% A549 cells at 2 μg/mL equivalent
Foscan(®)in vitro and significantly delayed
tumor growth in vivo due to cell apoptosis under TUNEL analysis without obvious
weight loss. Based on immunohistochemical observations, the
proliferating cell nuclear antigen (
PCNA)-negative area of
tumor sections after BRET-mediated
PDT was obviously increased compared to the
PDT-untreated groups without an external light source. We conclude that this nanotechnology-based
PDT possesses several clinical benefits, such as overcoming light penetration issues and treating deeper lesions that are intractable by
PDT alone.