Enhanced Energy Transfer in the Co‐assembly of Donor‐Receptor Polymer Nanoparticles: An Artificial Light Capture System to Trigger Effective Photodynamic Antibacterial Processes

Abstract

Light‐harvesting system is an important way for capturing, transferring and utilizing light energy. It remains a key challenge to develop highly efficient artificial light‐harvesting systems. Herein, we report a supramolecular co‐assembly based on 5,10,15,20‐tetrakis (4‐hydroxyphenyl) porphyrin (THPP) and fluorescein derivatives as an artificial light‐harvesting systems. The assemblies use fluorescein derivatives as a donor and porphyrin (THPP) as an acceptor unit by covalent linkage and achieved fluorescence resonance energy transfer (FRET) owing to their strong spectral overlap and short distance. Firstly, three linkers of different chain lengths were synthesized through bromoalkane, and three fluorescein derivatives were obtained by connecting the linker and fluorescein through covalent bonds according to the principle of substitution reaction. Then, FRET systems between fluorescein derivatives and THPP were developed. As a result, a nanocapsule with an ultrathin shell designed for mimicking natural light‐harvesting systems was successfully constructed based on the covalent assembly of donor molecule called fluorescein and acceptor molecule called THPP. To our delight, the covalent FRET probes achieved enhanced energy transfer and a longer fluorescence lifetime. The covalent FRET probes also showed the obvious growth inhibition of Staphylococcus aureus cells in photodynamic antibacterial. Therefore, this study provides a new and efficient strategy to construct artificial light‐harvesting systems and they hold great promise for photophysical and photochemical applications.