A novel bis(β-Br-BODIPY) photosensitizer and its nanoscale delivery systems based on polymer micelles and zeolite-like MOFs

The design of biocompatible photosensitizers with an optimal combination of intense fluorescence and generation of singlet oxygen is a complex and urgent task. The article presents the results of synthesizing, analyzing the structure, and examining the chromophoric, fluorescent, and generation characteristics of new dimeric bis(β-Br-BODIPY) (1), as well as the features of its encapsulation in ZIF-8 zeolite framework and solubilization by Pluronic® F127 micelles. The photophysical characteristics of brominated dimer 1 were analyzed in comparison with non-halogenated dimers bis(β-H-BODIPY) (2), bis(β-CH3-BODIPY) (3), as well as dibromo-substituted mononuclear analogue β,β-dibromo-BODIPY (4). Dye 1 exhibits efficient fluorescence (from 53 to 72%) and 1O2 generation (from 19 to 42%) in solutions of nonpolar and weakly polar solvents. Dimerization leads to a high sensitivity of the fluorescence and generation characteristics of the halogenated dimer 1 to the solvent. The advantage of dimer 1 is a significantly lower tendency to aggregate compared to monomer 4. The conditions for the encapsulation of dye 1 in ZIF-8 nanoparticles and Pluronic® F127 micelles were determined and their structural and spectral characteristics were analyzed.