Light-induced immunoassay can selectively detect coronavirus spike protein in five minutes

Just as moths are attracted to a flame, microbes can be navigated by light. Using this knowledge, researchers at the Research Institute for Light Acceleration Systems (RILACS), Osaka Metropolitan University, have demonstrated a method to rapidly detect the presence of viruses using only a small amount of sample.

The research team, led by OMU’s Professor Takuya Iida (Director of RILACS) and Associate Professor Shiho Tokonami (Deputy Director), reported their light-induced immunoassay method in npj Biosensing.

With less than a minute of laser irradiation, the plasmonic substrate imprinted with nanoparticles featuring an array of nanobowl structures (each 500 nm in diameter) could be coated with antibodies against the spike protein of the novel coronavirus.

A low-power 5-milliwatt laser, similar to that of a commercially available laser pointer, can form bubbles on the biochip to attract virus-mimicking nanoparticles, accelerating selective particle detection.

The particles did not need to be highly concentrated because the light-induced convection caused the nanoparticles to move around and eventually collect in the stagnant region between the substrate surface and the bottom of the bubble. The entire process, from substrate coating to detection, could be completed within 5 min.

“This research shows that it is possible to shorten the complicated antibody coating process and enable rapid and highly sensitive protein detection,” said Professor Iida. “We believe that this discovery can contribute to the early diagnosis not only of the new coronavirus, but also of various infectious diseases, cancers, and even dementia.”