What Color Does Phycocyanin Absorb?

Blue spirulina phycocyanin powder is a water-soluble protein pigment belonging to the class of phycobiliproteins. It is mainly found in cyanobacteria (such as spirulina) and red algae, and is a photosynthetic auxiliary pigment outside the chloroplast. Phycocyanin not only has a bright blue appearance, but also has strong light absorption ability. And it is widely used in photosynthesis, fluorescent probes, natural pigments, food additives, medicine and other fields. So what colors can phycocyanin absorb?

Light absorption principle of phycocyanin

Basic properties of light and color perception

Light is an electromagnetic wave, and different wavelengths of visible light correspond to different colors perceived by the human eye. The wavelength of visible light is roughly between 400 and 700 nm. Among them:

400–450 nm: purple, blue-purple

450–495 nm: blue

495–570 nm: green

570–590 nm: yellow

590–620 nm: orange

620–700 nm: red

The phycobilitin contained in phycocyanin can selectively absorb orange-red light of 600-650 nm. It reflects more blue light (about 450-495 nm), so it appears blue.

Light absorption at the molecular level

The electronic structure of phycobilin allows it to absorb photons of specific energy. When photons of orange-red wavelength hit the phycobilin molecule, the π electrons in the phycobilin are excited to a higher energy level and the energy is absorbed. This process is called electronic transition.

The excited phycobilin molecule transfers energy through non-radiative or radiative processes. Finally, it transfers energy to chlorophyll through the energy transfer chain for photosynthesis, or emits light in the form of fluorescence.

The influence of environmental factors on the absorption spectrum

The absorption peak position of blue spirulina phycocyanin powder is affected by many factors. Such as pH value, temperature, solution environment, protein conformation, etc. These factors may cause a slight shift in the absorption peak (called "spectral red shift" or "blue shift"). This affects its performance in different applications.

Molecular Structure & Spectral Characteristics

Molecular structure

The basic unit of blue spirulina phycocyanin powder is a heterodimer composed of two subunits, α and β. Each subunit is bound to a linear open-chain pigment molecule called phycocyanobilin (PCB). Phycobilin is a photosensitive group of phycocyanin that can absorb light of a specific wavelength.

The structure of the pigment group (phycobilin) of pure blue phycocyanin powder is similar to that of chlorophyll. But the difference is that it does not contain magnesium ions, but is composed of an open linear pyrrole ring. It has unique light absorption properties.

Absorption spectrum

The light absorption peak of phycocyanin is mainly concentrated between 600 and 650 nanometers (nm). The typical maximum absorption peak is around 615-620 nm. This wavelength corresponds to the orange-red spectral range. Because phycocyanin absorbs orange-red light and reflects blue-green light, we see that phycocyanin appears blue.

Its emission (fluorescence) peak is usually around 640-650 nm. This means that it can absorb light and emit red light in the form of fluorescence. This property makes blue spirulina phycocyanin powder not only a pigment but also a potential biofluorescent marker.

Application analysis of different colors

Pure Phycocyanin powder itself is blue, but its absorption and emission characteristics determine that it can show a variety of application colors and functions in different fields.

Food application of natural blue pigments

Blue spirulina phycocyanin powder has the characteristics of safe, natural, and non-toxic blue pigments. Therefore, it is widely used as a food colorant. Especially in the context of the growing demand for natural blue foods. Compared with synthetic blue pigments (such as indigo carmine), phycocyanin is more popular.

•Application areas:

Beverages, candies, ice cream, jelly, cakes, etc.

•Advantages:

Bright color, good stability, high nutritional value (containing protein and antioxidants).

Fluorescent labeling and biomedical fields

The emission spectrum of blue spirulina phycocyanin powder is in the red range. Its strong fluorescence characteristics make it an excellent biomarker. It plays an important role in fluorescent immunoassay and cell imaging.

•Color performance:

Emits red fluorescence after absorbing orange-red light, which is convenient for multi-color fluorescence detection and molecular tracking.

•Application examples:

Flow cytometer dyes, fluorescent antibody labels, in vivo imaging probes.

Color application in cosmetics

Phycocyanin, as a natural blue pigment, is also used in makeup and skin care products. At the same time, due to its antioxidant properties, it helps to delay skin aging.

•Applications:

Eye shadow, lipstick, facial mask, etc.

•Color function:

It can provide a natural blue tone to enhance visual appeal.

Fluorescent probe and optoelectronic applications

Blue spirulina phycocyanin powder has efficient light absorption and energy transfer capabilities. Therefore, it has become a research hotspot in the field of optoelectronics and fluorescent probes.

•Applications:

It is used in optical biosensors and solar energy conversion devices.

•Color performance:

This is to use its blue absorption and red emission to design multi-wavelength excitation and detection schemes.

Color function in bioluminescence and photosynthesis

In the natural environment, phycocyanin helps cyanobacteria absorb orange-red light in the spectrum, supplements the insufficient absorption of chlorophyll to blue-green light, and optimizes the efficiency of light energy utilization.

•Color function:

Phycocyanin can absorb orange-red light and reflect blue-green light.

Phycocyanin and other phycobiliproteins

As can be seen from the table, different phycobiliproteins absorb light in different wavelengths and present complementary colors, which provides a theoretical basis for the development of composite pigments.

As a natural blue-green photosynthetic pigment, phycocyanin mainly absorbs orange-red light (610-620 nm band) and reflects blue-green light. Its color performance is affected by pH, temperature, light and metal ions, showing a variety of blue-green changes. These color characteristics give blue spirulina phycocyanin powder a wide range of applications in food, cosmetics, medicine, biotechnology and other fields, which not only meets the needs of natural pigments, but also brings unique biological activity and functionality. In the future, with the development of molecular biology and materials science, the color regulation and application of phycocyanin will be more diverse and precise.

Guanjie Biotech is a blue spirulina phycocyanin powder manufacturer. We produce blue spirulina phycocyanin powder products of different specifications. If you need Blue Spirulina Phycocyanin Powder, please contact us at info@gybiotech.com.