Chemiluminescence resonance energy transfer-based nanoparticles for quantum yield-enhanced cancer phototheranostics.

Chemiluminescence (CL) has recently gained attention for CL resonance energy transfer (CRET)-mediated photodynamic therapy of cancer. However, the short duration of the CL signal and low quantum yield of the photosensitizer have limited its translational applications. Here, we report CRET-based nanoparticles (CRET-NPs) to achieve quantum yield-enhanced cancer phototheranostics by reinterpreting the hidden nature of CRET. Owing to reactive oxygen species (ROS)-responsive CO generation, CRET-NPs were capable of generating a strong and long-lasting photoacoustic signal in the tumor tissue via thermal expansion-induced vaporization. In addition, the CRET phenomenon of the NPs enhanced ROS quantum yield of photosensitizer through both electron transfer for an oxygen-independent type I photochemical reaction and self-illumination for an oxygen-dependent type II photochemical reaction. Consequently, owing to their high ROS quantum yield, CRET-NPs effectively inhibited tumor growth with complete tumor growth inhibition in 60% of cases, even with a single treatment.