Heart failure remains a leading cause of death worldwide, particularly among those with limited access to medical care. Addressing this challenge, a team of researchers has developed a groundbreaking point-of-care electrochemical biosensor. This innovative device, which resembles a transparent lateral flow COVID-19 test, can detect heart failure biomarkers using just a drop of saliva in under 15 minutes.

Trey Pittman, a graduate student at Colorado State University, is set to present his team’s findings at the American Chemical Society (ACS) Fall 2024 meeting. The event, held virtually and in person from August 18-22, will showcase around 10,000 scientific presentations, with Pittman’s research as a potential game-changer in heart failure screening.

“Our device is tailored for individuals at high risk of heart failure who lack easy access to hospitals or centralized labs,” Pittman explains. “This project hits close to home for me, being from Mississippi, where heart failure mortality rates are among the highest in the U.S.,” he adds.

Heart failure occurs when the heart muscle weakens, struggling to pump oxygen-rich blood throughout the body. The current standard for screening involves a biannual blood test measuring B-type natriuretic peptide (BNP) levels, a protein signaling that the heart is under stress.

However, the advent of point-of-care devices could revolutionize this approach, making heart failure screening as simple as a home saliva test. Pittman suggests that such a test could allow individuals to monitor their heart health every few weeks instead of waiting six months between screenings. Until now, the adoption of portable saliva tests for heart health has been hampered by complex manufacturing processes and limited data beyond a single biomarker's presence.

Pittman and his colleagues have tackled these issues head-on, producing an intuitive, low-cost biosensor prototype known as the electrochemical capillary-driven immunoassay (eCaDI). The handheld testing platform, developed by Charles Henry’s group at Colorado State University, combines two prior innovations: a saliva microfluidic device and a biosensor for the heart failure biomarkers Galectin-3 and S100A7. Collaborator Chamindie Punyadeera’s team at Griffith University in Australia quantified these biomarkers in saliva, linking them to heart failure outcomes.

The eCaDI device consists of five layers, resembling a club sandwich: three layers of clear, flexible plastic separated by double-sided adhesive.

• The top plastic layer features tiny holes for loading the saliva sample.
• The middle layer contains laser-cut channels that guide saliva through the device, with squares of blotting paper at the end drawing the sample from the loading site.
• Sandwiched between the outer layers are glass fiber reagent pads, which react with the saliva to measure Galectin-3 and S100A7 when an electrical current is applied.
• The bottom plastic layer has carbon ink electrodes screen-printed on its surface.
• Two electrodes, powered by an external device called a potentiostat, drive the chemical reaction on the reagent pads.

“The devices are incredibly easy to assemble,” says Pittman. “In just 20 to 30 minutes, we can produce five of them.” Each single-use eCaDI costs around $3.00, with the reusable potentiostat priced at approximately $20.

In demonstrations, the researchers spiked standardized human saliva samples with levels of the two biomarkers indicative of heart failure. The eCaDI successfully detected Galectin-3 and S100A7 levels in the saliva, marking a significant step towards developing a robust, non-invasive electrochemical sensor for heart failure biomarkers. The next phase of research will involve testing the eCaDI at Griffith University in human trials, involving both healthy individuals and those with heart failure.

“This work could serve as a foundation for new saliva testing platforms for other diseases,” Pittman shares. “It’s a technology that could help many people, particularly those underserved, live longer, healthier lives.”

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