Periodic Reporting for period 1 - deBioLED (Design of Bioinspired Chromophore-Protein Complexes for Color Converting Layers of Organic Light Emitting Diodes)
Periodo di rendicontazione: 2023-10-01 al 2025-09-30
The global transition to sustainable energy relates the development of new strategies for the photonics and optoelectronics sectors with the intention of eliminating the usage of toxic, scarce, or environmentally damaging materials. Solid-state lighting devices have become critical to reduce energy consumption and, thus, carbon emissions. The modulation of the color produced by such devices is usually done by means of Color Converting Layes (CCLs). However, the current state-of-the-art CCLs still rely on rare-earth elements, cadmium-based quantum dots, or complex inorganic nanomaterials. In this scenarium, organic chromophores are neglected due to their tendency to aggregate when processed in solution (leading to emission quenching), and for their poor photostability.
To tackle these issues, biogenic matrices as de novo designed protein maquettes offer an opportunity. These proteins synthetically produced by microoorganisms, can be designed to host chromophores in specific environments in order to tune their light emission efficiency and chemical stability. By doing so, organic chromophores can become sustainable CCLs of lighting devices through the processing with harmless solvents (e.g. water), avoiding molecular aggregation. Yet this technology remains underexplored in optoelectronics, leaving a gap between fundamental protein design and real-world applications. Therefore, the main objective of this project is to establish protein maquettes as a new platform for sustainable light conversion, demonstrating their capacity to stabilize chromophores in aqueous and environmentally friendly media, and enhance their optical and photophysical performance.
The political and strategic context underscores an urgent need for biodegradable, low-energy, and circular materials solutions – following pacts as the EU Green Deal, and the Critical Raw Materials Act.
To tackle these issues, biogenic matrices as de novo designed protein maquettes offer an opportunity. These proteins synthetically produced by microoorganisms, can be designed to host chromophores in specific environments in order to tune their light emission efficiency and chemical stability. By doing so, organic chromophores can become sustainable CCLs of lighting devices through the processing with harmless solvents (e.g. water), avoiding molecular aggregation. Yet this technology remains underexplored in optoelectronics, leaving a gap between fundamental protein design and real-world applications. Therefore, the main objective of this project is to establish protein maquettes as a new platform for sustainable light conversion, demonstrating their capacity to stabilize chromophores in aqueous and environmentally friendly media, and enhance their optical and photophysical performance.
The political and strategic context underscores an urgent need for biodegradable, low-energy, and circular materials solutions – following pacts as the EU Green Deal, and the Critical Raw Materials Act.
The project began with the expression of two four-α-helix bundle protein capable of binding organic chromophores with high specificity. After, I moved to the construction of the chromophore-protein complexes in a way that Maquette 1 served as host for Zn-pheophorbide a (ZnP) via histidine residues, and Maquette 2 served as host for a rhodamine derivative (ROX) via a maleimide group due to the mutation of one of its residues to a cysteine. For the binding of ROX to Maquette 2, a synthetic protocol had to be developed, including the protocol for complex characterization via Mass Spectrometry. Additionally, a third complex was constructed using Maquette 2, where ZnP and ROX were simultaneously present.
With the composition of the complexes, a detailed photophysical characterization followed by means of steady-state absorption and emission spectroscopies, time-resolved emission measurements, and circular dichroism analysis. The study reveled that the protein scaffolds prevented chromophores aggregation, enhanced quantum yields, narrowed emission bandwidths, and significantly stabilized the protein fold. Molecular dynamics simulations supported these observations by revealing the structuring of the chromophores and proteins.
Furthermore, low-temperature Stark spectroscopy was employed, revealing how the proteins contribute to modulate the chromophores electronic structure (in specific, their charge transfer character) and the occurence of new electronic transitions not present in isolated systems. The technique of Ultrafast transient absorption spectroscopy was also performed, providing the excited state dynamics, and uncovering a sub-picosecond non-resonant energy-transfer process from ROX to ZnP. Together, these results demonstrate that the protein scaffold enforces chromophore placement and orientation with the precision required to achieve directional, ultrafast energy transport reminiscent of natural photosynthetic antennas.
Finally, these complexes were incorporated into a hydrogel matrix so the maquettes could be processed as CCLs that were coupled to inorganic LEDs with the intention of modulating the diodes emission colors. The resulting hybrid devices produced deep-red and near-infrared light with high color purity. Notably, the maquette environment increased chromophores photostability, demonstrating a clear functional advantage for device integration.
With the composition of the complexes, a detailed photophysical characterization followed by means of steady-state absorption and emission spectroscopies, time-resolved emission measurements, and circular dichroism analysis. The study reveled that the protein scaffolds prevented chromophores aggregation, enhanced quantum yields, narrowed emission bandwidths, and significantly stabilized the protein fold. Molecular dynamics simulations supported these observations by revealing the structuring of the chromophores and proteins.
Furthermore, low-temperature Stark spectroscopy was employed, revealing how the proteins contribute to modulate the chromophores electronic structure (in specific, their charge transfer character) and the occurence of new electronic transitions not present in isolated systems. The technique of Ultrafast transient absorption spectroscopy was also performed, providing the excited state dynamics, and uncovering a sub-picosecond non-resonant energy-transfer process from ROX to ZnP. Together, these results demonstrate that the protein scaffold enforces chromophore placement and orientation with the precision required to achieve directional, ultrafast energy transport reminiscent of natural photosynthetic antennas.
Finally, these complexes were incorporated into a hydrogel matrix so the maquettes could be processed as CCLs that were coupled to inorganic LEDs with the intention of modulating the diodes emission colors. The resulting hybrid devices produced deep-red and near-infrared light with high color purity. Notably, the maquette environment increased chromophores photostability, demonstrating a clear functional advantage for device integration.
In deBioLED, I established de novo designed protein maquettes as a powerful new platform for sustainable photonic technologies. By engineering robust four-α-helix bundles capable of binding multiple chromophores with high specificity, the work demonstrates that synthetic proteins can be programmed to modulate chromophore photophysics in ways that rival natural pigment–protein complexes.
I showed that protein maquettes can significantly enhance the optical performance of Zinc pheophorbide a (ZnP) and a rhodamine derivative (ROX), yielding narrowed emission spectra, higher emission quantum yields, and exceptional thermal stability, with chromophore-protein complexes possessing melting temperatures exceeding 90 °C. When employed as CCLs in hybrid LEDs, these assemblies produced deep-red and near-infrared emission with high color purity and improved photostability. Notably, the protein environment increased chromophore photostability under continuous illumination. In this way, the work serves as a proof of concept that sustainable materials as protein maquettes can serve as CCLs for solid state lighting devices.
I also demonstrated that maquettes can serve as hosts of multiple chromophores to achieve directional and ultrafast energy transfer. Using Stark spectroscopy, femtosecond transient absorption, and molecular dynamics simulations, my work reveals that the protein scaffold precisely tunes chromophores’ dipole moments, polarizability, and electronic coupling, enabling sub-picosecond energy transfer from ROX to ZnP. These results show that artificial proteins can replicate fundamental design principles of natural photosynthetic antennas, as for spectral complementarity, controlled pigment positioning, and rapid energy flow within a fully programmable synthetic framework.
Collectively, these findings open avenues for a new generation of bioengineered materials for optoelectronics, artificial photosynthesis, indoor farming and solar fuel generation. To translate this potential into practical technologies, next steps include further optimization of proteins design to ensure chromophore loading and long-term performance comparative with the lifespan of comercial solid-state lighting devices. By doing so, the project will achieve significant results for intelectual property.
I showed that protein maquettes can significantly enhance the optical performance of Zinc pheophorbide a (ZnP) and a rhodamine derivative (ROX), yielding narrowed emission spectra, higher emission quantum yields, and exceptional thermal stability, with chromophore-protein complexes possessing melting temperatures exceeding 90 °C. When employed as CCLs in hybrid LEDs, these assemblies produced deep-red and near-infrared emission with high color purity and improved photostability. Notably, the protein environment increased chromophore photostability under continuous illumination. In this way, the work serves as a proof of concept that sustainable materials as protein maquettes can serve as CCLs for solid state lighting devices.
I also demonstrated that maquettes can serve as hosts of multiple chromophores to achieve directional and ultrafast energy transfer. Using Stark spectroscopy, femtosecond transient absorption, and molecular dynamics simulations, my work reveals that the protein scaffold precisely tunes chromophores’ dipole moments, polarizability, and electronic coupling, enabling sub-picosecond energy transfer from ROX to ZnP. These results show that artificial proteins can replicate fundamental design principles of natural photosynthetic antennas, as for spectral complementarity, controlled pigment positioning, and rapid energy flow within a fully programmable synthetic framework.
Collectively, these findings open avenues for a new generation of bioengineered materials for optoelectronics, artificial photosynthesis, indoor farming and solar fuel generation. To translate this potential into practical technologies, next steps include further optimization of proteins design to ensure chromophore loading and long-term performance comparative with the lifespan of comercial solid-state lighting devices. By doing so, the project will achieve significant results for intelectual property.