Ancestral Protein‐Based Lighting

Protein‐optoelectronics is a paradigm toward eco‐designed and sustainable technologies. The challenge is, however, how to preserve the native activity of proteins upon device fabrication/operation in non‐native environments (solvents, organic/inorganic interfaces, and working temperatures/irradiations). Herein, a new vision to identify and design ancestral‐like fluorescent proteins (FPs) is proposed. Using ancestral sequence reconstruction (ASR) out of a large dataset (221) of the best modern FPs suitable for photon down‐conversion in bio‐hybrid light‐emitting diodes (Bio‐HLEDs) a historical‐genetic reconstruction (family tree) was obtained, identifying a possible common ancestral FP. This computationally designed protein is produced in bacteria, featuring outstanding photoluminescence quantum yields in solution (e.g., 90%/80% for green‐/red‐emitting forms) and a strong tendency to agglomerate in polymer coatings. This resulted in red‐emitting Bio‐HLEDs that outperformed the reference with ≈2‐fold enhanced stabilities. The resplendent green‐/red‐emission of ancestral‐like FP itself and its respective devices led us to coin this new protein as QuetzalFP. Overall, it is set in ASR as an effective concept to reshape protein‐optoelectronics allowing us to identify i) many interesting ancestral FPs for lighting and ii) QuetzalFP as stepping‐stone platform for protein engineering.