BODIPY Derivatives for Photodynamic Therapy: Influence of Configuration versus Heavy Atom Effect

Heavy atom effect and configuration are important for BODIPY derivatives to generate singlet oxygen (¹O₂) for photodynamic therapy. Herein, a series of BODIPY derivatives with different halogens were synthesized. ¹O₂ quantum yields (QYs) and MTT assay confirm that incorporation of more heavy atoms onto dimeric BODIPY cannot effectively enhance the ¹O₂ QYs. Rather, the dark toxicity increases. This phenomenon can be attributed to the competition of heavy atom effect and configuration of dimeric BODIPY. In addition the BODIPY derivative with two iodine atoms (BDPI) owns the highest ¹O₂ QYs (73%) and the lowest phototoxicity IC₅₀ (1 μM). Furthermore, an in vivo study demonstrates that BDPI NPs can effectively inhibit tumor growth and can be used as a promising threanostic agent for photodynamic therapy in clinic.