Phosphate-Assisted Transformation of Methylene Blue to Red-Emissive Carbon Dots with Enhanced Singlet Oxygen Generation for Photodynamic Therapy

Photodynamic therapy (PDT) has attracted wide attention due to its distinct advantages in cancer treatment. Herein, a kind of red emissive carbon dots (R-CDs) was synthesized from methylene blue (MB) and phosphate through a hydrothermal method. The resultant R-CDs display good biocompatibility, photostability, and high singlet oxygen (O-1(2)) yield (0.91); thus, they have been successfully applied to the PDT study in vitro. More importantly, the R-CDs show noninfective property to DNA, which is substantially different to their precursor MB. The structure of R-CDs was comprehensively characterized both experimentally as well as by density functional theory (DFT) calculations. This study not only provides a rational strategy for preparation of highly efficient PDT material but also gives insight into the mechanism of O-1(2) generation.

Automated summary

This study focused on the synthesis of red emissive carbon dots (R-CDs) for photodynamic therapy (PDT) in cancer treatment. The R-CDs displayed good biocompatibility, photostability, and high singlet oxygen yield, and showed noninfective property to DNA. The study comprehensively characterized the structure of R-CDs and provided insights into the generation mechanism of singlet oxygen.