Infectious diseases cause over 10 million deaths worldwide each year, with low-income countries bearing the greatest burden. Limited access to reliable diagnostic tools, costly equipment, and shortages of trained personnel lead to delayed or missed diagnoses. Now, a new portable and affordable test delivers lab-quality accuracy in just 15 minutes from a single drop of blood, offering rapid detection even in low-resource settings.

Researchers at Arizona State University (Tempe, AZ, USA) have developed NasRED (Nanoparticle-Supported Rapid Electronic Detection), a diagnostic device that uses gold nanoparticles engineered to detect extremely small amounts of disease-related proteins. The nanoparticles are coated with antibodies or antigens that bind to specific targets from viruses, bacteria, or the body’s immune response. The device shines an LED light through a sample, and more light signals that the nanoparticles have sunk, indicating disease presence.

When a sample such as blood, saliva, or nasal fluid is added, nanoparticles will sink if a target disease is present, leaving the upper fluid clearer. NasRED can detect disease when only a few hundred molecules are present, reaching the attomolar range of sensitivity. The system has been shown to be roughly 3,000 times more sensitive than ELISA and is nearly 100,000 times more sensitive than standard laboratory tests. Each test costs about USD 2 and requires no specialized training or expensive equipment.

In a study published in ACS Nano, NasRED detected the COVID-19 virus with pinpoint accuracy and distinguished it from other infections. It was roughly 3,000 times more sensitive than ELISA, needed 16 times less sample volume, and produced results 30 times faster. The technology has also demonstrated detection of Ebola, E. coli, cancer biomarkers, and Alzheimer's-related proteins.

The system’s modular design allows rapid adaptation for different diseases, making it suitable for early detection of hepatitis C, HIV, Lyme disease, and emerging outbreaks. Researchers aim to miniaturize and automate the device for potential home use, combining the convenience of rapid tests with unmatched sensitivity. Future applications could include early cancer detection and chronic disease monitoring.

"We have the speed and ease of use of a rapid antigen test with sensitivity that’s even better than lab-based tests — a combination that’s very difficult to achieve," said Chao Wang, Associate Professor, Biodesign Center for Molecular Design and Biomimetics, Arizona State University.

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