Low-Cost Blood Probe Targets Rheumatic Heart Disease

Rheumatic heart disease (RHD) claims hundreds of thousands of lives each year, devastating children and young adults in low- and middle-income countries where access to specialized ultrasound equipment and refrigerated testing labs is virtually nonexistent. Inexpensive penicillin could stop the progressive valve damage if detected early, yet millions remain undiagnosed until irreversible heart failure sets in.

Now, researchers from Ben-Gurion University of the Negev (BGU) have engineered a synthetic, antibody-free diagnostic probe that detects cardiac inflammatory biomarkers in blood without requiring cold-chain refrigeration or complex laboratory machinery. The peer-reviewed study, published in ACS Sensors, lays the groundwork for affordable, rapid point-of-care screening in rural and underserved communities.

The research was led by Prof. Ayelet David alongside Ilana Teboul, Naama Shlush, Maya Droby, and Dr. Yvonne Ventura from BGU’s Department of Clinical Biochemistry and Pharmacology, in collaboration with the late Prof. Robert A. Levine of Massachusetts General Hospital and Harvard Medical School.

The Diagnostic Bottleneck in Global Health

Triggered by untreated group A streptococcal throat infections, rheumatic fever causes chronic inflammation that progressively thickens, scars, and calcifies cardiac valves. Although regular antibiotic injections can prevent recurrent damage, identifying patients before heart valves are destroyed currently demands echocardiography machines or complex antibody-based blood assays such as ELISA.

Standard ELISA testing relies on biological antibodies that are expensive to manufacture, vulnerable to heat degradation, and dependent on multistep processing. In low-resource clinics lacking continuous refrigeration or automated equipment, widespread immunoassay screening is virtually impossible.

A 'Light-Up' Molecular Tripwire

To bypass biological antibodies entirely, the BGU team built a fully synthetic, polymer-based sensor using an HPMA backbone functionalized with specific peptide ligands and near-infrared fluorescent dyes. The probe is engineered to function like an optical switch:

Built-in Optical Silencing: When floating freely, the polymer remains tightly clustered, bringing the dye molecules into close proximity so they naturally absorb and quench each other's light.

Biomarker-Activated Signal: When the synthetic peptides encounter E-selectin—a key adhesion molecule shed into the blood during active valvular inflammation—the polymer uncoils, pulling the dyes apart and producing a sharp "turn-on" fluorescent glow.

Direct Blood Sensing: In laboratory trials, the probe successfully captured and quantified E-selectin directly in complex serum samples, producing a clear, dose-dependent optical readout on standard microplate readers.

Breaking the Cold-Chain Barrier

"Current diagnostics depend heavily on delicate animal-derived antibodies that spoil if they aren't kept on ice," says lead researcher Prof. Ayelet David. "By replacing antibodies with robust synthetic polymers and peptides, we have created a platform that is inherently stable, significantly cheaper to manufacture, and resilient to ambient temperatures. It is built specifically to survive real-world conditions where cold-chain logistics simply don't exist."

No established blood biomarker is currently available for diagnosing RHD. A panel of markers is therefore needed to tell RHD patients apart from non-rheumatic valvular disease and other inflammatory conditions. By simply swapping the targeting peptides, the same polymer backbone can be adapted to detect biomarkers for many vascular and inflammatory diseases. While current sensitivity operates in the microgram range and further optimization is underway to detect minute nanogram-level concentrations in early-stage patients, the modular design provides an immediate translational platform.

This work was supported by research grants from the Leducq Foundation as part of the PRIMA (Preventing Rheumatic Injury BioMarker Alliance) Network (Grant No. 22ARF02) and supported in part by the Israel Science Foundation (Grant No. 2033/25).