Self-assembled boron dipyrromethene-based nanocarriers with encapsulated doxorubicin for chemo-photodynamic therapy

The development of water-soluble boron dipyrromethene (BODIPY) dyes is important for biomedical applications as it offers the potential to form a drug self-delivery system with superior drug utilization. Herein, the amphiphilic BODIPY dye NBDP with good water solubility and superior onsite singlet oxygen generation ability was obtained, in which the chemotherapy drug doxorubicin (DOX) was loaded for achieving a synergistic combination of chemotherapy and photodynamic therapy. The introduction of hydrophilic chains at the 3,5 -position through the Knoevenagel reaction enhanced the water solubility and lengthened the conjugated structure of NBDP, resulting in a red shift of the spectrum to the near-infrared (NIR) region. The introduction of iodine atoms at the 2,6-position enhanced the intersystem crossing through the heavy atom effect and promoted singlet oxygen generation (phi(delta) = 71.1%), thereby enhancing the photodynamic therapy. Meanwhile, encapsulated DOX endowed the nanodrug with a chemotherapeutic effect, which compensated for the defects of photodynamic therapy, including the limitation of treatment depth. In vitro and in vivo experiments revealed the actualisation of NIR fluorescent imaging-guided chemo-photodynamic synergistic therapy. Hence, this multifunctional nano-system without extra carriers provides greater insight into the development of drug self-delivery systems with high drug utilization for the multi-modal diagnosis and treatment of cancer.