Supercharged Fluorescent Protein-Apoferritin Cocrystals for Lighting Applications

The design of lighting sources based on fluorescent proteins (FPs) has been limited by the lack of protocols to stabilize FPs under preparation (deposition techniques, organic solvents, etc .) and working (temperature, irradiation, etc .) conditions. As a critical bottleneck, photo-induced heat generation due to FP motion and quick heat transfer leads to working device temperatures of ca . 70 °C, resulting in a quick FP-denaturation and, in turn, a quick loss of the device performance. Herein, we showcase FP stabilization for lighting devices with an electrostatically self-assembled FP-apoferritin cocrystals embedded in a silicone-based color down-converting filter. This strategy highlights three major advances: i ) engineering of positively supercharged FPs (+22) without losing photoluminescence and thermal stability compared to its native form, ii ) a crystallization protocol resulting in highly emissive cocrystals keeping the photoluminescence features of the FPs, and iii ) a 40-fold increase of the lighting device stability compared to reference devices due to the reduction of the device working temperatures to 40 °C. Thus, the success of this multidisciplinary approach contributes toward developing stable energy-related protein-based optoelectronics. ### Competing Interest Statement The authors have declared no competing interest.