Because light exhibits excellent spatiotemporal resolution, photodynamic therapy (PDT) is becoming a promising method for cancer treatment. However, in a single photosensitizer (PS), it remains a big challenge to achieve all key properties including effective singlet oxygen (1O2) production under long-wavelength laser and bright near-infrared (NIR) emission without toxicity in the dark. In addition, clinically used traditional PSs encounter quenched fluorescence and decreased 1O2 production because of molecular aggregation in aqueous solution. To solve the aforementioned issues, quinoxalinone CN (QCN) with effective 1O2 generation under long-wavelength (530 nm) laser irradiation and aggregation-induced NIR emission is rationally designed by precise optimization of the quinoxalinone scaffold. After being encapsulated by an amphiphilic polymer (DSPE-PEG), the yielded nanoparticles exhibit highly efficient 1O2 production and stable NIR fluorescence located at 800 nm without obvious toxicity under the dark. Both in vitro and in vivo evaluation identify that QCN would be a promising PS for image-guided PDT of tumors.
Keywords: QCN; near-infrared (NIR) fluorescence; photodynamic therapy; quinoxalinone; singlet oxygen.