Protein Cohabitation: Improving the Photochemical Stability of R-Phycoerythrin in the Solid State

The poor photochemical stability of R-phycoerythrin (R-PE) has been a bottleneck for its broad-spectrum applications. Inspired by nature, we studied a sustainable strategy of protein cohabitation to enhance R-PE stability by embedding it in a solid matrix of gelatin. Both pure R-PE and fresh phycobiliprotein (PBP) extracts recovered from Gracilaria gracilis were studied. The incorporation of R-PE in the gelatin-based films (gelatin-RPE and gelatin-PBPs) has improved its photochemical stability for at least 8 months, the longest time period reported so far. These results were evidenced by not only absorption but also emission quantum yield measurements (Φ). Moreover, the photostability of gelatin-RPE films upon continuous excitation with an AM1.5G solar simulator was tested and found to remain stable for 23 h after initial decreasing up to 250 min. In the end, another approach was established to allow 100% photostability for a 3 h exposure to an AM1.5G solar simulator by doping the gelatin-based film including R-Phycoerythrin with n-propyl gallate stabilized with Tween 80, allowing their use as naturally based optically active centers in photovoltaic applications.