Improving Access to Saliva-Based Heart Failure Screening

Trey Pittman, a graduate student at Colorado State University, will present his team’s research at the fall meeting of the American Chemical Society (ACS).

“Our device would be ideal for people who are at high risk for heart failure but have limited access to a hospital or centralized lab,” Pittman says. “Working on this project to address health inequities in rural and low-income areas is very important to me because I’m from Mississippi, which has one of the highest rates of heart failure mortality in the United States,” he shares.

Heart failure refers to a weakened heart muscle that can’t pump enough oxygenated blood through the body. The current gold standard for screening for heart failure is a blood test performed twice a year by a healthcare provider that measures levels of B-type natriuretic peptide (BNP), a protein that indicates the heart is working too hard.

But new developments in point-of-care devices could level the proverbial playing field in health care with simple, at-home saliva tests. Such a heart failure screening test could be done by a person to check their health every few weeks, rather than every six months, Pittman suggests. So far, widespread use of portable saliva tests to check heart health has been limited by complicated manufacturing techniques and a lack of relevant data beyond the presence or absence of a single biomarker.

Pittman and colleagues have taken on these challenges and have promising results to share with an intuitive, inexpensive biosensor prototype they call the electrochemical capillary immunoanalyzer (eCaDI). Charles Henry’s group at Colorado State University combined two of their previous innovations to create a portable testing platform: a microfluidic saliva device and a biosensor for the biomarker proteins Galectin-3 and S100A7. Collaborator Chamindie Punyadeer’s group at Griffith University in Australia quantified levels of Galectin-3 and S100A7 in saliva, which correlated with heart failure outcomes.

eCaDI for heart failure consists of five layers – like a club sandwich: three layers of transparent, flexible plastic joined by alternating layers of double-sided adhesive.

• The top layer of plastic has tiny holes drilled into it for inserting a saliva sample.
• The middle layer of plastic has laser-cut channels with tissue paper squares on the ends that drain saliva away from the loading site through the channels.
• Placed between the outer layers of plastic are glass fiber reagent pads containing compounds that react with saliva and measure levels of galactin-3 and S100A7 when an electrical current is applied to the device.
• On the surface of the lower plastic layer, electrodes made with carbon ink are screen-printed.
• Two electrodes, powered by small wire terminals from an external source called a potentiostat, drive the chemical reaction occurring in the reagent fields.

“The devices are very easy to assemble,” Pittman says. “We can do five of them in about 20 to 30 minutes.” The eCaDI is disposable, and the researchers estimate that each one costs about $3.00. The potentiostat, a small, reusable power source, costs about $20.

In the demonstration, the researchers spiked standardized human saliva samples with two biomarkers that indicate heart failure. Their results showed that eCaDI accurately detected levels of galactin-3 and S100A7 in saliva. “These demonstrations are the first step toward a robust, noninvasive electrochemical sensor for biomarkers of heart failure,” Pittman says. Next, the team will test eCaDI in clinical trials in humans at Griffith University, both healthy and with heart failure.

“This work could be a starting point for new saliva testing platforms for other diseases,” Pittman says. “It’s a technology that I think could help many people—especially the underserved—live longer, healthier lives.”

The research was funded by the US National Institutes of Health.