The Hokkaido University group and Imura Japan Co., Ltd. have jointly succeeded in developing an innovative biosensor that combines a solar cell and plasmon.As a result, a surface plasmon resonance (SPR) biosensor that detects proteins using an antigen-antibody reaction can be realized with a small device.
The SPR sensor that has already been put into practical use is a mechanism that optically detects a slight change in the refractive index of light that occurs on a metal surface based on the binding of an antibody, and requires a relatively large device for the detection system.On the other hand, the newly developed plasmon biosensor uses the interaction between the confined light and plasmon for electrical detection by combining it with a thin-film solar cell that has the function of confining light, resulting in highly sensitive detection and compact system. It was possible to make it at the same time.
Specifically, it is a sensor in which silicon is formed on a conductive glass substrate and a thin film of gold is formed on the film.When light is incident from a certain angle and surface plasmons are induced, the light is used to excite SPR, so the photocurrent value inside the silicon decreases, but as the antigen-antibody reaction progresses, the refraction of the gold surface Since the rate changes, surface plasmons are no longer induced, and as a result of light being confined in the silicon film and reciprocating, a strong light current flows.Proteins can be detected electrically by amplifying the photocurrent value, and it can be used for both antigen and antibody tests.
In fact, when the developed plasmon biosensor was chemically modified with an antibody and reacted with the nucleocapsid protein of the new coronavirus (SARS-CoV-2), which is an antigen, a large electrical signal conversion was observed in about 2 minutes. It was demonstrated that the antigen can be measured quantitatively.
By developing a new principle that sharply changes the optical change of plasmon into an electric signal, we have achieved a significant compactness and high sensitivity of the SPR sensor system, so in the future, it will be wearable like clothes. It is expected to be applied as a biosensor.
Paper information:[Nature Communications] A Fabry-Pérot cavity coupled surface plasmon photodiode for electrical biomolecular sensing
