DNA Sensor Enables Molecular Detection from Single Blood Drop

Accurately monitoring drug levels in patients’ blood remains a major challenge in modern medicine. Each patient’s pharmacokinetic profile varies, leading to inconsistent drug exposure — underdosing can cause treatment failure and resistance, while overdosing increases toxicity. Current methods for measuring therapeutic drug concentrations are slow and costly. Now, researchers have created a DNA-based digital test that can measure drug levels in just five minutes using an inexpensive reader.

The innovation was developed by researchers from the Université de Montréal (Quebec, Canada) who drew inspiration from the nanoscale signaling cascades that living cells use to sense and respond to their environment. These biological cascades are composed of biomolecules that interact precisely to trigger cellular responses. Replicating this natural design, the researchers engineered synthetic DNA-based signaling cascades capable of detecting and quantifying molecular targets through a measurable electrochemical signal.

Each DNA molecule is programmed to react specifically to certain drugs, translating molecular recognition into an electrical output. The sensing mechanism operates through a molecular component known as an aptamer — a DNA molecule that binds selectively to the target drug. When the drug binds to the aptamer, it prevents the inhibition of another electroactive DNA strand that generates an electrical current. This current can then be easily read by a low-cost electrochemical reader. The process allows precise measurement of multiple molecular concentrations from a single drop of blood, producing results in minutes.

The study, published in the Journal of the American Chemical Society, shows that when validated through experiments in mice, the test successfully detected four distinct molecules, including real-time monitoring of an anti-malaria drug. Current gold-standard methods for such analysis require hours of preparation and specialized instruments, whereas this approach achieves comparable accuracy in a fraction of the time.

The device’s simplicity and versatility make it suitable for point-of-care or even at-home testing, similar to portable glucometers used by diabetic patients. By enabling faster and more accessible therapeutic monitoring, this DNA-powered system could transform personalized medicine and ensure safer, more effective treatment for a wide range of diseases.

“A great advantage of these DNA-based electrochemical tests is that their sensing principle can also be generalized to many different targets, allowing us to build inexpensive devices that could detect many different molecules in five minutes in the doctor's office or even at home," said UdeM chemistry professor Alexis Vallée-Bélisle who led the research group.

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