The simultaneous role of porphyrins' H- and J- aggregates and host-guest chemistry on the fabrication of reversible Dextran-PMMA polymersome.

Aggregation-induced quenching of porphyrin molecules as photosensitizer significantly reduces the quantum yield of the singlet oxygen generation, and it is able to decrease the efficacy of photodynamic therapy. We utilized amphiphilic copolymers in this work to precisely control porphyrin H-type and J-type aggregations in water. The amphiphilic copolymer bearing azobenzene, β-cyclodextrin, and porphyrin was successfully synthesized by the atom transfer radical polymerization technique. The azobenzene and β-cyclodextrin complex, as a host-guest supramolecular interaction, has great potential in the design of light-responsive nanocarriers. The amphiphilic block copolymer can be self-assembled into polymersomes, whose application in the generation of singlet oxygen has been also tested. We further demonstrate that, due to the stable H- and J-aggregates of porphyrin, which act as noncovalent cross-linking points, the structure of polymersomes can be reversible under light-stimulus. This formation method has the advantage of allowing for both the encapsulation of hydrophilic and hydrophobic molecules and release upon external light without any distinguishable changes in the structure. Furthermore, the morphology and particle size distribution of the polymersomes were also investigated by using transition electron microscopy, dynamic light scattering, and field emission scanning electron microscopy.