More than a year into a pandemic that has brought the world to its knees, the need to quickly and easily detect infectious pathogens has become indisputable. We’ve seen COVID-19 kill more than three million people, overwhelm health systems, and devastate economies.
“We don’t want to raise public fears, but having COVID around, you start to realize this is a type of disease that could be used as a bioweapon,” says Anna Ignaszak, a University of New Brunswick chemist. That’s why she and her team recently published an article in Nature’s Microsystems & Nanoengineering examining the use of specialized sensors to quickly detect highly contagious diseases and biological weapons.
Along with chemistry master’s student Connor O’Brien and undergraduate chemistry student Kathleen Varty, Ignaszak describes a wide array of electrochemical sensors for detecting some of the world’s most dangerous biological agents – anthrax, botulism, smallpox, plague, viral hemorrhagic fevers such as Ebola virus and Marburg virus.
The main advantage of electrochemical sensors, the researchers say, is that they deliver results in minutes, as opposed to hours, they are light-weight and portable, and can be operated by non-experts. They’re also extremely sensitive and cost slightly less than current biohazard sensing platforms.
While a forthcoming paper will zero in on the COVID-19 virus, the researchers hope their current overview of electrochemical sensors highlights the technology’s advantages over other detection systems, and encourages more widespread use in public venues.
“If we can detect each of these pathogens before they reach a community, thousands of lives could be saved, and we could better prevent the uncontrollable spread of disease,” O’Brien says in a news release.
Ignaszak says she’d particularly like to see these sensors used in airports, where there are no standardized procedures for screening methods.
“Ebola is only determined based on temperature measured at the point of entry or exit, and can often deliver false negatives as fever is a common symptom of many infections,” she says.
“In the case of botulism, conventional laboratory confirmation in a human specimen is required. These procedures require a longer analysis time and can only be carried out by trained professionals in clinical settings.”
By contrast, electrochemical sensors are simple devices that can be operated by anyone, says Ignaszak, who points to blood glucose sensors for diabetics as a prime example.
How they work
Most sensors start with a conductive platform consisting of gold or carbon nanoparticle electrodes. A sensing biomolecule – a short sequence protein known as an aptamer – is then bonded to the conductive platform.
When exposed to a human blood, urine or saliva sample containing pathogens, this biomolecule in turn bonds to the pathogens’ biomarkers – perhaps fragments of DNA or proteins.
Once bonded, the platform’s electrical parameters change in ways that are unique to specific pathogens. Changes in the charge, voltage and impedance (a form of resistance) might signal anthrax or small pox for example. Each of these changes is a result of the chemical reactions occurring at the test surface.
Jesse Greener, a materials scientist at Université Laval who uses electrochemistry to study biomaterials, agrees electrochemical sensors have important advantages.
“However, in many biorecognition techniques sample-specific assays are driven by functionalized electrodes or analyte-specific treatments that target known biomolecules,” he says. “In other words, you have to know what you are looking for and they should be specific to your target.”
Plus, he says, the potential for pathogen variants means that a biothreat can be missed if its surface protein biomarkers have evolved or been modified.
While Ignaszak acknowledges this, she says electrochemical sensors still offer significant advantages. In fact, they could be extended for use in other areas – for example, detecting cancer biomarkers and toxins in soil and water.