COVID-19 detection using wavelength shift when binding

The device, described in a proof-of-concept study published this week in Biosensors and Bioelectronics, uses portable lab-on-a-chip technology to accurately measure the concentration of antibodies present in diluted blood plasma.

The researchers avoided this trade-off between accuracy and accessibility by developing an alternative antibody testing platform that combines a powerful light-sensing technology with a microfluidic chip. 

"The test doesn't just detect whether the antibodies are present or absent—it also provides information about the quantity of antibodies produced by the immune system. In other words, it's quantitative," 

The antibody testing platform consists of a microfluidic chip which is integrated with a fiber optic light probe. The chip itself is made from a gold-covered glass slide with an embedded microfluidic channel. Using an electric voltage, the team fabricated tens of thousands of tiny spiky gold structures, each one smaller than the wavelength of light, on a glass slide.

The researchers then modified these gold nanospikes by attaching a fragment of the SARS-CoV-2 spike protein.

it based on the unique behavior of electrons on the surface of the gold nanospikes, which oscillate together when hit by light. These resonating electrons are highly sensitive to changes in the surrounding environment, such as the binding of antibodies, which causes a shift in the wavelength of light absorbed by the nanospikes.

 

 

reference

Riccardo Funari et al, Detection of antibodies against SARS-CoV-2 spike protein by gold nanospikes in an opto-microfluidic chip, Biosensors and Bioelectronics (2020). DOI: 10.1016/j.bios.2020.112578