It was hypothesised that the role of biliproteins in insects would also have a role related to light-absorption similar to that in plant and algae biliproteins. However, when the photochemical properties required for light-absorption were found absent in the biliprotein of the large white butterfly, this hypothesis was eliminated, followed by the assumption that those photochemical properties also do not occur in any other insect biliproteins. Based on these examinations, it was concluded that insect biliproteins are only loosely related to those from plants and algae, due to the large number of differences they have regarding structure, chemical composition, derivation of bilins and general functions. Fluorescent proteins have had a substantial impact on bioimaging, which is why biliproteins have made suitable candidates for the application, due to their properties of fluorescence, light-harvesting, light-sensitivity and photoswitching (the latter occurring only in phytochromes). Phycobiliproteins, which are highly fluorescent, have been used in external applications of bioimaging since the early 1980s. That application requires the bilin chromophore to be synthesised from haem, after which a lyase is needed to covalently bond the bilin to its corresponding apoprotein. An alternative method of uses phytochromes instead; some phytochromes only require one enzyme, haem oxygenase, for synthesisng chromophores. Another benefit of using phytochromes is that they bind to their bilins autocatalytically. While there are photochromic pigments with poor fluorescence, this problem has been alleviated by engineering protein variants that reduce photochemistry and enhance fluorescence. Properties of phycobiliproteins, such as their natural antioxidant, anti-inflammatory, food colourant, strong pigment and anti-aging activities, have given them considerable potential for use in food, cosmetics and medicinal applications. They have also proven to be therapeutic in treating diseases such as Alzheimer's disease and cancer. Given their large range of applications and potential uses, researchers have been trying to find and develop ways to produce and purify phycobiliproteins to meet the growing demand for them. One such phycobiliprotein is C-phycocyanin (C-PC), which is found in spirulina. A limiting factor of C-PC's usage in these applications is its protein stability, given that in its natural form, C-PC is highly sensitive to light and heat when in aqueous solution, due to its photosensitive phycocyanobilin (PCB) chromophore, which also makes it prone to free-radical oxidation.