Bioinspired Construction of Light-Harvesting Systems via Protein Self-Assembly Strategies

ConspectusPhotosynthesis is a vital process that sustains life on Earth, and its energy transfer mechanism can be elucidated by fluorescence resonance energy transfer (FRET), a process in which fluorescence donors and acceptors provide energy transfer through long-range dipole–dipole interactions. Constructing artificial light-harvesting systems (ALHSs) assists in the exploration and mimicry of natural light-harvesting systems (LHSs) and is expected to provide a potential solution to the energy crisis. Structures fabricated by the self-assembly of proteins provide ideal templates and skeletons for the construction of ALHSs, as they enable the orderly arrangement of chromophores and effectively prevent the aggregation-induced quenching effect of dyes. The programmability and designability of the proteins and their flexible assembly strategies allow for diverse and functionalized protein-based template construction, making them ideal template nanomaterials for constructing ALHSs.In this Account, dealing with the strategy and the structural diversity of protein self-assemblies, we will first introduce the driving forces and assembling strategies of protein self-assembly. Then, based on our long-term research on protein self-assemblies, we will summarize our work on the development and exploration of ALHSs constructed in our laboratory in recent years, using polymorphic protein-assembly structures as templates. We will discuss the specific effects of different protein templates on energy transfer. Finally, the challenges and proposed possible strategies for the design of future LHSs by integrating proteins with nanotechnology interface science are presented.Considering the highly codable and designable nature of proteins, as well as the definite and delicate structure of their assemblies on the nanoscale, we propose the strategy of “using protein assemblies as templates to construct ALHSs”. Protein template backbones can be constructed through both noncovalent (electrostatic, metal-chelation, host–guest interactions) and covalent interactions. Furthermore, the dynamic processes of protein assembly and disassembly are important, as we believe that flexible protein assembly and construction strategies can mimic the self-regulatory functions of the adaptive natural photosynthetic system.Based on the “energy funneling” step flow transfer mechanism, different dimensions of protein self-assembly show their specific characteristics in the construction of ALHSs. One-dimensional (1D) protein self-assemblies feature linearly arranged chromophore molecules with linear energy transfer, mimicking light-harvesting antennas. In comparison, two-dimensional (2D) protein backbones provide more multidirectional energy transfer paths for chromophores or pigment molecules, avoiding overall transfer interruption from individual position defects. We found that the diverse assembly strategies among proteins allow the assembly structure to be regulated by a stimulus-responsive mechanism. This mechanism can modulate the efficiency of energy transfer, which further controls the catalytic performance of the ALHS in model reactions. In summary, protein self-assemblies not only achieve stabilization and orderly arrangement of chromophores but can also control energy transfer by manipulating their degree of assembly.