Separation and Purification of C-Phycocyanin from Spirulina platensis Using Aqueous Two-Phase Systems Based on Triblock Thermosensitive Copolymers

C-phycocyanin is a high market value compound derived from cyanobacterium Spirulina platensis and has a wide range of applications in pharmaceutical and food industries as a useful biochemically active compound. In this study, essentially an aqueous two-phase system (ATPS) is presented for purification of C-phycocyanin. The phase behavior of ATPSs that include Pluronic copolymers and salts was evaluated systematically. After that, the effects of different parameters such as salt type, copolymer structure, pH of solution, tie line length (TLL), system's temperature, and volume ratio for purification of C-phycocyanin were investigated. The results revealed that Pluronic 10R5/potassium phosphate buffer system is the most appropriate system for promoting the C-phycocyanin separation from other contaminants. Besides, the purity index of C-phycocyanin was enhanced by up to 3.92 at TLL of 46.31%, pH = 6, volume ratio of 0.34, and temperature of 35 degrees C without any loss of stability. At these conditions, the obtained C-phycocyanin recovery was 90%. After that, the purity factor reached to 5.9 by applying the ultrafiltration method. In addition, the results of circular dichroism (CD) spectroscopy proved that the C-phycocyanin structure remained intact during the purification step. Finally, 78% of 10R5 copolymer was recovered by increasing the temperature above 57 degrees C (micelle formation (which can be used in new ATPS.