Biosensors

Having looked at how photonic nanostructures are manufactured, this video shows how they are converted into biosensors.

The biosensors developed at the University of York combine the diffraction and Bragg mirror effects described previously. With an appropriate design, the light can be made to go back and forth within the structure many times. This back-and-forth oscillation is described as a resonance and, because the light goes back and forth along the surface in this case, we call it a ‘surface resonance’. When we shine white light onto the grating, only the resonant wavelength is reflected: the particular wavelength which equals the grating period (λ=g).

By attaching specific antibodies to the surface of the photonic nanostructure, we can make it sensitive to different biomarkers. For example, we might want it to detect biomarkers for infection. When the biomarker we want to detect binds to the antibody on the photonic nanostructure, the peak of the resonance shifts. By measuring this shift, we can detect not only the presence of the biomarker we are interested in, but also its concentration.

Biosensors use a similar principle to that already being used in biomedical laboratories by researchers studying the interactions between protein biomarkers or developing new drugs. However, the photonic nanostructure sensors allow some major advantages. The sensor can be incorporated into a handheld instrument that can be used in a GP practice or even at home, and it only requires a single drop of blood. One of the main applications will be testing for infections (viral or a bacterial), so that healthcare professionals can administer the most appropriate treatment.

The handheld instrument has already demonstrated that it can reach the required level of performance, but it needs to be tested in clinical trials before becoming commercially available.