Saliva-based biosensor could improve heart failure detection

Australian scientists have created a biosensor that can rapidly detect the heart failure biomarker S100A7 in saliva, offering a simple, non-invasive way to identify the disease. Their work has been published in the journal Biosensors and Bioelectronics: X.

Heart failure affects 64 million people worldwide, but current diagnostic methods face significant limitations. Blood tests, clinical evaluations and imaging technologies are often expensive and can be geographically inaccessible — especially in remote and under-resourced communities — leading to delayed diagnoses and limited treatment options.

“Early symptoms are often subtle and non-specific, meaning patients typically receive treatment only in advanced disease stages,” said first author Dr Roxane Mutschler, of the ARC Centre of Excellence in Synthetic Biology at the Queensland University of Technology (QUT).

Co-author Dr Zhengling Cui, also from QUT, said the COVID-19 pandemic has increased interest in exploring non-invasive and easily accessible biofluids for heart failure diagnostics. Saliva is increasingly being utilised to detect systemic diseases, including cancer and cardiovascular conditions, as it mirrors what’s happening in the system.

S100A7 was discovered by Professor Chamindie Punyadeera’s team at Griffith University; healthy people typically have lower levels of S100A7 in their saliva, while heart failure patients have roughly twice as much. But instead of using the body’s natural antibodies to detect problems, the researchers used a technique called mRNA display to custom-build their own protein detectors from scratch.

The team created millions of different versions and let them compete to see which ones best latched onto the heart failure marker. The winning designs were then produced in bacteria — like brewing beer, but for proteins. This synthetic biology approach is known to be faster and cheaper than traditional methods.

When the team tested saliva from 31 heart failure patients, their biosensor matched results from standard medical tests 81% of the time. Importantly, it was better at correctly identifying people who didn’t have heart failure (82% accuracy vs 52% for standard tests).

Mutschler said a test to diagnose or detect a variety of conditions at the point of care will alleviate the pressure on centralised testing laboratories or hospitals.

“This work contributes to the development of personalised health care by aiding people to detect signs and symptoms before the onset of a condition and to easily monitor its progression,” she said. The work should also make heart failure screening more accessible, especially in remote and under-resourced communities.

The researchers admitted that their study was small, so they would need to conduct wider testing before it can be used in clinics. They are also working on improving it to handle an even wider range of protein levels. But the early results are promising, with the team saying the same approach could work for other diseases as they can swap out the detection piece to look for different warning signs in the body.

“It’s like changing the attachment on a power tool,” Mutschler said. “The basic system stays the same, but you can adapt it to detect different health problems.”

Image credit: iStock.com/Annadokaz