Template-Free Construction of Highly Ordered Monolayered Fluorescent Protein Nanosheets: A Bioinspired Artificial Light-Harvesting System

Using biological materials for light-harvesting applications has attracted considerable attention in recent years. Such materials provide excellent environmental compatibility and often exhibit superior properties over synthetic materials. Herein, inspired by the outstanding energy transfer performance in coelenterates, we constructed a template-free, highly ordered two-dimensional light-harvesting system by covalent-induced coassembly of EBFP2 (donor) and EGFP (acceptor), in which the fluorescent chromophores were well distributed and adopted a fixed orientation. By introducing approximate square planar binding sites on the side surface of protein, assembly pattern was pin down and self-assembly extended in orthogonal directions to achieve monolayered and tessellated protein nanoarrays. The excellent antiself-quenching property of fluorescent proteins endowed the coassembled system with attractive light-harvesting capability. Even at high local concentrations, a low resonance energy transfer self-quenching was observed and, therefore, energy can be efficiently transferred. More importantly, the distance between adjacent chromophores is continuously adjustable. By making minor changes to the length of the inducing linker, we have achieved significant control over the size of the assembly. A micron-sized light-harvesting system with satisfactory energy transfer efficiency was finally obtained. This work developed a template-free light-harvesting system completely based on fluorescent proteins (FPs), which overcame the restriction of using templates. Not limited to this work, the special core-shell structure of FPs may be expected to direct the optimization of fluorescent dyes by cladding.

近年来，利用生物材料进行光捕获应用引起了人们的广泛关注。此类材料具有优异的环境兼容性，并且通常表现出优于合成材料的性能。在此，受腔肠动物出色的能量转移性能的启发，我们通过共价诱导EBFP2（供体）和EGFP（受体）共组装构建了无模板、高度有序的二维光捕获系统，其中荧光发色团分布均匀并采用固定方向。通过在蛋白质侧面引入近似正方形的平面结合位点，固定组装模式并在正交方向上延伸自组装，以实现单层和镶嵌的蛋白质纳米阵列。荧光蛋白优异的抗自猝灭特性赋予了共组装系统有吸引力的光捕获能力。即使在高局部浓度下，也观察到低共振能量转移自猝灭，因此，可以有效地转移能量。更重要的是，相邻发色团之间的距离是连续可调的。通过对诱导连接子的长度进行微小的改变，我们已经实现了对组件大小的显着控制。最终获得了具有令人满意的能量传输效率的微米级光捕获系统。这项工作开发了一种完全基于荧光蛋白（FP）的无模板光捕获系统，克服了使用模板的限制。不仅限于这项工作，FP的特殊核壳结构有望通过包覆来指导荧光染料的优化。