The tissue penetration depth of light and the
singlet oxygen (1O2) generation efficiency of
photosensitizers (PSs) are the two main factors that determine the effectiveness of
photodynamic therapy for
tumors. Herein, we report a novel strategy to prepare a multifunctional upconversion
photosensitizer (UCPS) based on the host/guest nanoarchitecture. By a simple reprecipitation method, host/guest
tetracene/
pentacene nanorods (Tc/Pc NRs) were synthesized for enhancing triplet-triplet annihilation-upconversion (TTA-UC) or two-photon excited emission and 1O2 generation efficiency upon 650 or 808 nm excitation. Tc/Pc NRs had higher 1O2 quantum yield (74%) than Tc NRs (28%) upon 650 nm
laser irradiation. The proposed mechanism is that doping Pc molecules into Tc NRs induces intermediate states between S0 and S1, shortening the energy gap for 1O2 generation and resulting in TTA-UC emission. Equally important, with 808 nm fs
laser excitation, Tc/Pc NRs showed an enhanced 1O2 generation efficiency and two-photon absorption cross section (σ) compared with Tc NRs. In addition, when the
tumors in mice were exposed to Tc/Pc NRs with 650 or 808 nm wavelength irradiation, the
tumor inhibition rates achieved 99 and 95%, respectively. This work opens new perspectives for exploring novel nano-UCPSs for biomedical applications.