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When ultraviolet light is shone on foams, they glow in the dark. The phosphorescence could be used to image biological samples under the microscope.
Phosphorescent materials absorb high-energy light and gradually release the energy as light of a longer wavelength. It is possible for this afterglow to last for hours or even minutes.
Ultralong organic phosphorescence is a persistent glow that can be seen in some carbon-based, organic materials. Researchers can tailor organic materials for anti-counterfeiting and optical sensor applications by altering their structures, which is easier than making them from inorganic phosphors. Ultralong organic phosphorescence materials tend to be brittle and contain toxic components, which have limited their practical use.
The RIKEN Center for Emergent Matter Science and colleagues have discovered that a mixture of peptides and proteins can be turned into a strong organic phosphorescence material.
The researchers created porous foams with the help of water and freeze-dried gelatin. The strongest foam was produced when the mixture was chilling to -10 degrees Celsius. A piece of foam the size of a sugar cube can support a 40 kilogram weight, despite being 80% air. The foams had regular structures with similar shapes and sizes.
After the team shone the light on the foams, they glowed yellow-green. Ishida was surprised when his student found that the foams had strong organic phosphorescence. It was impossible to imagine such a strong phosphorescence based on the structure of the molecule.
The foams' ultralong organic phosphorescence was caused by clusters of chemical groups called carbonyls. Their phosphorescence lifetime decreased after they were exposed to air.
The team made similar foams from different materials. The foams all showed phosphorescence activity that was blue or deep green. They were phosphoresce because of the mixing of gelatin with PVA and PVP.
The non-toxic foams are being developed as ecofriendly materials for optical sensors.
The Journal of the American Chemical Society has more information about Suzhi Cai and her research. There is a DOI: 10.1021/jacs.1c07674.
The Journal of the American Chemical Society has information.
Gelatin foams show unexpected ultralong organic phosphorescence for optical applications.
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