Nature-inspired biomineralization process for the development of a stable phycocyanin - apatite multifunctional system for biomedical applications

In the last decade Spirulina, also called Arthrospira platensis, has been introduced by the research as one of the most effective biologically active compounds, both for its health benefits and ability to prevent and treat diseases or their symptoms. Spirulina is a photosynthetic cyanobacterium also known as blue-green microalgae. This organism contains a variety of bioactive macromolecules, as well as unsaturated fatty acids and essential amino-acids, which contribute to basic human nutrition. In addition, it contains other compounds, such as chlorophylls, carotenoids, phycocyanins, which give it its typical bright blue color. However, among all the Spirulina components, the most attractive is the active C-phycocyanin. Phycocyanin is a water-soluble phycobiliprotein, known as the only blue food coloring authorized by the FDA and often used in candy, cold drinks, beverages etc. However, recently it has been discovered that phycocyanin has important applications in the biomedical field, such as anti-oxidant, anti-inflammatory, anti-bacterial molecule and immune system stimulator in critical disease. The main using problem of the extracted phycocyanin, however, is its poor stability depending from temperature, pH and light. Indeed, it easily produces precipitates and changing color rapidly deactivating itself and limiting its wide application. To face this issue, through a natural-inspired approach in this work a stable anti-oxidant and antibacterial phycocyanin-based hybrid compound has been developed and tested. This biomimetic multifunctional system was thought for the designing of a new cosmetic and medical generation products, such as for sunscreen and wound healing. Reproducing the natural biomineralization process, phycocyanin molecules were conjugated with nanostructured hydroxyapatite particles (PcHA), obtaining a hybrid compound characterized from a light blue color. It has been fully investigated by chemical- physical and morphological analysis, in particular stability tests have been performed under different conditions of temperature, pH, and light, demonstrating the chemical stability of phycocyanin when conjugated with HA particles. Furthermore, the antioxidant properties evaluation has highlighted the preservation of molecule efficacy even atier biomineralization. Its optimal cytocompatibility and antibacterial activity, demonstrated by in vitro cellular tests, suggest that PcHA could be promising for many biomedical applications. In particular, its antioxidant effect can be exploited in cosmetic products, especially in sunscreens, to protect skin tissue against free radicals (ROS) damage. While, Pc anti- inflammatory and antibacterial activity can play an important role in the chronic wounds treatment. Its ability to improve skin wounds has already been demonstrated, thus PcHA particles could be functional for dressing patches or topical formulations development.