Measuring the Storm

Overproduction of cytokines can lead to a “cytokine storm” – an extreme inflammatory reaction triggered by numerous health conditions, including COVID-19, cardiovascular disease, rheumatoid arthritis, and Alzheimer’s disease. Detection of cytokine biomarkers at low concentrations can help diagnostic professionals to identify the risk earlier. And although existing methods – such as ELISA and mass spectroscopy – are extremely sensitive, they are expensive and time consuming. And that’s why a group of Canadian researchers developed a rapid, label-free, molybdenum disulfide (MoS₂) diode-based biosensor that detects one particular cytokine: TNF-alpha (1).

“The sensor we are developing is simple to use and portable so it could potentially be used in a doctor’s office or in more remote areas where access to laboratories is limited,” says Michael Adachi, the project’s lead investigator. “The advantage of the diode sensor is its simple electrical readout and fabrication process,” he continues.

The geometric asymmetry makes the sensor highly sensitive to any changes that occur at the surface. Next, the sensor is functionalized with TNF-alpha binding aptamers. So, when a small volume of solution containing TNF-alpha comes into contact with the sensor, it interacts with the aptamers, causing an observable change in the electrical properties of the biosensor crystal. By measuring the electrical signal output, the concentration of the biomarker protein can be assessed. “These biomarkers are indicators that can help determine if a person may have or be at risk of developing a disease,” says Adachi. 

There may be potential for this method to be applied in the detection of other biomarker proteins, and in other diseases, such as Alzheimer’s. For now, the team is working to overcome the challenges of targeting one specific protein in a sea of interfering substances, including hormones and salts. Indeed the next phase of the current study will assess sensor performance using blood samples – which may demonstrate its potential for scalability in the future.