White-emitting Protein-Metal Nanocluster Phosphors for Highly Performing Biohybrid Light-Emitting Diodes.

This work presents a simple in situ synthesis and stabilization of fluorescent gold nanoclusters (AuNCs) with different sizes using engineered protein scaffolds in water. The protein-AuNC hybrids show a dual emission (450 and 700 nm) with a record photoluminescence quantum yield of 20%. These features impelled us to apply them to biohybrid light-emitting diodes as color down-converting filters or biophosphors. Efficient white emission (x/y CIE color coordinates of 0.31/0.29) and stabilities of more than 800 h were achieved. This represents a 2 orders of magnitude enhancement compared to the prior art. Besides the outstanding performance, the protein scaffold also infers a unique anisotropic emission character that is considered as a proof-of-concept of high interest for single-point lighting and display.

When Fluorescent Proteins Meet White Light-Emitting Diodes.

Over the last decades, fluorescent proteins (FPs) have been extensively employed for imaging and tracing in cell biology and medicine. However, their application for lighting devices like light-emitting diodes (LEDs) and lasers has recently started. The interest of FPs is the result of their good photoluminescence features (high emission efficiency with a narrow spectrum and a high photon-flux saturation), good photostability, sustainable production by bacteria, and eco-friendly recycling. Their low stability at high temperatures as well as the need for an aqueous environment have, however, strongly limited their use in optoelectronics. This has recently been circumvented with new coating systems that are paving the way for the entrance of FPs into the LED field. In this Minireview, we summarize the first steps taken by a few groups towards the development of bio-hybrid white LEDs (Bio-HWLEDs) with a focus on using FPs as color down-converters, highlighting the state of the art and challenges associated with this emerging field.

Single-Component Biohybrid Light-Emitting Diodes Using a White-Emitting Fused Protein.

This work presents a pioneering multidisciplinary approach toward enhancing biohybrid light-emitting diodes (BioHLEDs), merging synthetic biology tools, polymer chemistry, and device engineering to design a thin color down-converting coating with a single white-emitting fluorescent protein (WFP). In particular, the WFP consists of fused red-, green-, and blue-emitting FPs following the so-called protein superglue approach. This WFP shows an efficient and stable white emission originated from a Förster resonance energy transfer between FP moieties. The emission chromaticity is, in addition, easily controlled by the rigidity of the polymer matrix of the coating, reaching photoluminescence quantum yields of 26% that stand out among intrinsic white-emitting materials. The WFP single-component color down-converting packaging was applied to fabricate BioHLEDs featuring efficient neutral white emission that is stable over 400 h. This represents the most stable BioHLED reported to date. Thus, this work is a landmark for the use of synthetic biology tools to design tailored luminescent biomaterials for lighting applications.