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C-Phycocyanin is a natural blue pigment with many commercial applications in foods, cosmetics, and medicines. In this paper we describe the extraction and purification of C-phycocyanin from the cyanobacterium Spirulina platensis. The procedure is based on adsorption of impurities with chitosan and activated charcoal then one-step ion-exchange chromatography. The dry algal powder was soaked in potassium phosphate buffer for 2 h to furnish crude phycocyanin extract of purity 0.93. The crude extract was then treated with chitosan and activated charcoal for 5 min, which increased the purity to 2.78. After chromatography on DEAE Sephadex A-25, the purity of phycocyanin was improved to 4.3. The identity of the purified phycocyanin was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis and by spectroscopic measurements (UV-visible spectrophotometry and spectrofluorimetry). Compared with conventional methods, this method was simple, inexpensive, and time-saving.

Smart biomaterials have been rapidly advancing ever since the concept of tissue engineering was proposed.

Photodynamic therapy (PDT) or photothermal therapy (PTT) using nanomaterials has shown great prospect for cancer treatment. Phycocyanin (PC) is a photoharvesting pigment and is also an attractive candidate for PDT. The multiwalled carbon nanotube (MWNT) is a potent candidate for PTT due to its extraordinary photo-to-thermal energy conversion efficiency upon excitation with near-infrared (NIR) light. To date, although MWNT-CS complexes have been well studied, no report about the reconjugation of MWNT-CS with phycocyanin is available in the literature. Here, by using water-soluble chitosan (CS), we prepared and characterized a novel biomaterial, MWNT-CS-PC, with the potential for PDT and PTT. The cytotoxicity experiments found that MWNT-CS-PC exhibited cell growth inhibition activity. Moreover, with irradiation of NIR light (808 nm) or visible light (532 nm), the photoinduced cytotoxicity was indeed enhanced. These results suggest that MWNT-CS-PC may potentially serve as a future photodynamic and photothermal therapy for cancer.

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