R-phycoerythrin extraction and purification from fresh Gracilaria sp. using thermo-responsive systems
R-phycoerythrin is a high added-value protein found in red macroalgae with several interesting properties. Despite the promising results found when R-phycoerythrin is used as an optically active center in luminescent solar concentrators (LSCs), it still has some problems that can be attributed to the low stability of the R-phycoerythrin in the presence of the specific contaminant proteins found in the crude extract. The development of downstream strategies able to reduce the use of environmentally hazardous solvents, while improving the purification without compromising the R-phycoerythrin structural integrity is still the biggest challenge to overcome. Aqueous micellar two-phase systems (AMTPS) appear as an appealing fractionation approach since they allow the processing of systems with larger water contents, while displaying great selectivity and biocompatibility with several biomolecules. Moroever, AMTPS that mix surfactants and surface-active ionic liquids are shown to significantly enhance protein purification. In this work, mixed AMTPS were applied to the R-phycoerythrin purification from red macroalgae. After the process optimization, this work proposes the application of two consecutive steps of purification as the final process to isolate R-phycoerythrin from the remaining proteins composing the crude extract, while maintaining the structural integrity of R-phycoerythrin, as requested to be used in the LSC. Besides a good performance, the two-step approach developed was also shown to have a lower environmental impact with a carbon footprint decrease of 16%, when compared with the conventional AMTPS.