Programmably switching the NIR upconversion for orthogonal activation of photoacoustic imaging and on-demand phototherapy

Abstract Upconversion nanoparticles (UCNPs) based phototheranostics offer significant expectations for the personalized cancer medicine via integrating both modalities of imaging diagnostics and phototherapeutics. However, programmably controlling the photoactivation of imaging and therapy towards the accurate diagnosis with minimum side effects for on-demand therapy has remained challenging due to the lack of ideal switchable UCNPs agents. Herein, we demonstrate a facile strategy to simply switch the near infrared emission at 800 nm from rationally designed UCNPs by modulating the irradiation laser into pulse output. Through synthesis of the theranostic UCNPs-DI agent combining with a photosensitizer and a photoabsorbing agent assembled on the UCNPs, the orthogonal activation of in vivo photoacoustic imaging and photodynamic therapy was further achieved by simply altering the excitation modes from pulse to continuous-wave output upon a single 980-nm laser. Importantly, no obvious harmful effects during photoexcitation caused by reactive oxygen species (ROS) photooxidation and photohyperthermia were generated under imaging modality, which facilitates the long-term and real-time imaging-guidance for the subsequent phototherapy. This work provides a new facile approach for the orthogonal activation of imaging diagnostics and photodynamic therapeutics towards the target cancers.