Fireflies

From fireflies to lantern fish, many animals possess the chemical tools to produce light. Typically, this reaction requires the substrate luciferin and the enzyme luciferase. However, a class of less discriminating luciferins, known as imidazopyrazinone-type (IPT) compounds, can glow when encountering other proteins, including ones that aren't considered enzymes. Previous research suggests that IPT luciferins could serve as the basis for a new type of medical test that uses luminescence to announce the presence of a target protein in a specimen. Ryo Nishihara, Ryoji Kurita and colleagues suspected that an IPT luciferin could react with the SARS-CoV-2 spike protein, which allows the virus particles to invade cells and cause COVID-19 - and open the door to develop a glowing test.

For more:

https://www.news-medical.net/news/20240118/Researchers-develop-a-potential-one-minute-COVID-19-test-inspired-by-bioluminescence.aspx