Non-Covalent Assembly of Multiple Fluorophores in Edible Protein/Lipid Hydrogels for Applications in Multi-Step Light Harvesting and White-Light Emission

The design and production of biodegradable and sustainable non-toxic materials for solar-energy harvesting and conversion is a significant challenge. Here, our goal was to report the preparation of novel protein/lipid hydrogels and demonstrate their utility in two orthogonal fundamental studies-light harvesting and white-light emission. Our hydrogels contained up to 90% water, while also being self-standing and injectable with a syringe. In one application, we loaded these hydrogels with suitable organic donor-acceptor dyes and demonstrated the energy-transfer cascade among four different dyes, with the most red-emitting dye as the energy destination. We hypothesized that the dyes were embedded in the protein/lipid phase away from the water pools as monomeric entities and that the excitation of any of the four dyes resulted in intense emission from the lowest-energy acceptor. In contrast to the energy-transfer cascade, we demonstrate the use of these gels to form a white-light-emitting hydrogel dye assembly, in which excitation migration is severely constrained. By restricting the dye-to-dye energy transfer, the blue, green, and red dyes emit at their respective wavelengths, thereby producing the composite white-light emission. The CIE color coordinates of the emission were 0.336 and 0.339-nearly pure white-light emission. Thus, two related studies with opposite requirements could be accommodated in the same hydrogel, which was made from edible ingredients by a simple method. These gels are biodegradable when released into the environment, sustainable, and may be of interest for energy applications.

Automated summary

The design and production of biodegradable and sustainable non-toxic materials for solar-energy harvesting and conversion is a significant challenge. Here, the researchers successfully prepared novel protein/lipid hydrogels that can be used for both light harvesting and white-light emission studies. The hydrogels have a high water content of up to 90% and exhibit self-standing and injectable properties. They demonstrated the energy-transfer cascade among different dyes and achieved white-light emission by restricting the dye-to-dye energy transfer. These hydrogels, made from edible ingredients, are biodegradable, sustainable, and have potential applications in the energy field.