| Fluoroboron dipyrromethene（BODIPY）compounds possess excellent optical properties,such as high molar extinction coefficients,high fluorescence quantum yields,narrow fluorescence emission bandwidths,photostability.However,due to their hydrophobic and rigid conjugated structures,BODIPY compounds tend to aggregate throughπ-πstacking in aqueous solutions or in biological environments,leading to fluorescence quenching（ACQ）and intersystem crossing（ISC）from the S1 state to the T1 state,which favors the generation of the T1state.Therefore,the ISC process of BODIPY fluorophores can be regulated by utilizing a self-assembly strategy,resulting in conventional development of heavy atom-free photosensitizers for the efficient photodynamic therapy（PDT）or photocatalysis.In this study,a series of BODIPY derivatives were synthesized and investigated to explore the molecular self-assembly in aqueous solutions,and their photodynamic and photocatalytic effects were studied in detail.Herein,two aspects were investigated:（1）Self-assembly photosensitization and PDT study of long-chain substituted BODIPY derivatives.We synthesized nine BODIPY derivatives（BY-I2,BY-I8,BY-I12,BY-I16,BY-I18,BY-Br8,BY-Br12,BY-Br14,BY-Br22）with different lengths of alkyl chains,and studied their self-assembly behavior and photosensitization process in aqueous solutions.The test data showed that the monomers of these compounds could only produce fluorescence but not generate ROS.Scanning electron microscopy and dynamic light scattering data showed that BY-I12 self-assembled in aqueous solution to form spherical aggregates with a diameter of about 150 nm,and this aggregate could effectively generate 1O2 under light conditions,which was a type II photosensitizer.BY-I16/BY-I18 self-assembled in aqueous solution to form J-aggregates with a rhombic dodecahedral shape.Under light conditions,they could not only produce 1O2,but also generate O2·-,which was a type I/II mixed photosensitizer.CCK-8 cell toxicity data showed that the self-assembled aggregates of BY-I16/BY-I18had high phototoxicity and low dark toxicity under both normoxic and hypoxic conditions.Experimental results of PDT treatment of mouse tumor showed that BY-I16/BY-I18 self-aggregation effectively inhibit and ablate tumor under laser irradiation.Routine blood tests showed little difference between BY-I16/BY-I18aggregates and control groups.No abnormal cell morphology or tissue damage was found in H&E staining images.Therefore,BY-I16 and BY-I18 self-aggregates have good in vivo biocompatibility and excellent biosafety,which is conducive to in vivo application.（2）Study on aggregation-induced photosensitization and photocatalysis of BODIPY derivatives.We synthesized 11 kinds of BODIPY derivatives by introducing different substituents into the meso site of BODIPY.The aggregation behavior of the BODIPY derivatives in aqueous solution was investigated by spectroscopy,and the SEM and DLS results showed that the BODIPY derivatives formed spherical aggregates in aqueous solution.The detection experiment of reactive oxygen indicators showed that the compounds could produce 1O2 after aggregation in aqueous solution.Under the same testing conditions,1O2 generated the aggregates of BY-SMe,BY-SEt,and BY-Seph generated 15.45,16.36,and 13.63 times more 1O2 than methylene blue,respectively.Next,we studied the photocatalytic oxidation reaction of methylphenyl sulfide by three types of aggregates.The experimental results showed that the aggregates of BY-SMe,BY-SEt,and BY-Seph all achieved effective oxidation. |
