Synthesis and Properties of Bright Red-to-NIR BODIPY Dyes for Targeting Fluorescence Imaging and Near-Infrared Photothermal Conversion.

An efficient synthesis of 3-pyrrolylBODIPY dyes has been developed from a rational mixture of various aromatic aldehydes and pyrrole in a straightforward condensation reaction, followed by in situ successively oxidative nucleophilic substitution using a one-pot strategy. These resultant 3-pyrrolylBODIPYs without blocking substituents not only exhibit the finely tunable photophysical properties induced by the flexible meso-aryl substituents but also serve as a valuable synthetic framework for further selective functionalization. As a proof of such potential, one 3-pyrrolylBODIPY dye (581/603 nm) through the installation of the morpholine group is applicable for lysosome-targeting imaging. Furthermore, an ethene-bridged 3,3'-dipyrrolylBODIPY dimer was constructed, which displayed a near-infrared (NIR) emission extended to 1200 nm with a large fluorescence brightness (2840 M-1 cm-1). The corresponding dimer nanoparticles (NPs) afforded a high photothermal conversion efficiency (PCE) value of 72.5%, eventually resulting in favorable photocytotoxicity (IC50 = 9.4 µM) and efficient in vitro eradication of HeLa cells under 808 nm laser irradiation, highlighting their potential application for photothermal therapy in the NIR window.

Unique Double Intramolecular and Intermolecular Exciton Coupling in Ethene-Bridged aza-BODIPY Dimers for High-Efficiency Near-Infrared Photothermal Conversion and Therapy.

Spatial electronic communications of chromophores are both theoretically and practically fascinating. Despite intramolecular or intermolecular exciton coupling was observed in multichromophoric oligomers and J-aggregates, respectively, it is unusual that they both occur in the same molecule. Herein, ethene-bridged aza-BODIPY dimers with intramolecular exciton splitting have been developed. By encapsulating the dimer into F-127 polymer, J-type aggregated nanoparticles were produced, which showed obvious intermolecular exciton coupling and dramatically redshifted absorption and emission peaks at 936 and 1003 nm, respectively. The fabricated nanoagents have high photothermal conversion ability (η=60.3 %) and are ultra-photostable, leading to complete tumor ablation with 915 nm laser irradiation. This phototherapeutic nanoplatform through modulating both intra- and intermolecular exciton couplings is a valuable paradigm for developing photothermal agents for tumor treatment.