New Biosensor Detects Airborne H5N1 and E. coli in Under Five Minutes

By Dr. Noopur JainReviewed by Bethan DaviesMar 21 2025

A new capacitive biosensor has the ability to detect airborne H5N1 and E. coli with impressive speed and sensitivity.

This biosensor uses an electrochemical capacitive detection strategy that simplifies the testing process while significantly cutting down detection time. The goal is to provide a reliable tool for real-time monitoring and early detection of airborne pathogens.

Why This Matters

Avian influenza A (H5N1) and E. coli are two pathogens that pose serious health threats, especially when transmitted through the air. H5N1, in particular, remains a global concern due to its potential to mutate and spread among humans. These pathogens travel via aerosols, making timely detection critical in high-risk environments like hospitals, farms, and food production facilities.

Traditional detection methods, such as PCR and standard electrochemical assays, are often too slow or cumbersome for real-time monitoring. They typically require complex sample preparation, labeling steps, and specialized reagents. In contrast, electrochemical capacitive biosensors (ECBs) offer a label-free, faster alternative—measuring subtle changes in capacitance when a pathogen binds to a sensor surface.

This study takes ECBs a step further by designing a sensor that pairs advanced materials with an integrated aerosol sampling system, allowing for direct, efficient detection of airborne threats.

Inside the Sensor

At the core of the biosensor is a screen-printed carbon electrode (SPCE) modified with an interlocked network of Prussian blue (PB) and graphene oxide (GO). This network was created using electro-co-deposition, which enables the simultaneous growth of GO branches and decoration with PB nanocrystals. The result is a highly interconnected structure that enhances electrochemical responsiveness.

To target specific pathogens, the sensor surface was functionalized with anti-H5N1 aptamers and anti-E. coli antibodies. Capacitance changes caused by pathogen binding were monitored using electrochemical impedance spectroscopy—a technique sensitive enough to detect even small molecular interactions.

The researchers optimized the PB-to-GO ratio and fine-tuned deposition time using cyclic voltammetry (CV), ensuring the biosensor performed consistently across a wide range of pathogen concentrations.

To collect samples, the team used a custom-built wet cyclone bioaerosol sampler, which pulls airborne particles into a liquid medium for analysis—making the overall system both portable and adaptable to real-world use.

What They Found

The biosensor delivered strong results across key performance metrics:

• H5N1 detection range: 2.0 to 1.6 × 10⁵ viral RNA copies/mL
• Limit of detection (LoD): 56 RNA copies/mL
• E. coli detection range: 2.0 to 1.8 × 10⁴ bacterial cells/mL
• LoD: 5 bacterial cells/mL

Perhaps most impressively, both pathogens were detected in under five minutes. When paired with the cyclone sampler, the system achieved airborne detection thresholds as low as 93 RNA copies/m³ for H5N1 and 8 bacterial cells/m³ for E. coli.

Accuracy exceeded 90 % in aerosol samples, thanks to refined binary detection techniques and sample dilution adjustments. These findings demonstrate the sensor's readiness for environments where speed and precision are non-negotiable.

To verify the results, the team cross-checked their data using droplet digital PCR (dPCR). Results closely matched, with only minor discrepancies in one sample. The biosensor also showed strong specificity: no cross-talk occurred between H5N1 and E. coli signals, even near their detection limits—a key feature for multiplexed diagnostics.

Conclusion

This capacitive biosensor offers a compelling solution for real-time detection of airborne pathogens. By using a label-free electrochemical approach, the device cuts down on testing time and operational complexity without sacrificing accuracy or sensitivity.

Its modular design also allows for integration with various sampling systems, opening the door to broad deployment across industries. Whether in healthcare, agriculture, or public health surveillance, the sensor could play a vital role in identifying infectious threats early—helping contain outbreaks before they spread.

The technology also has potential beyond H5N1 and E. coli. With some modification, it could be adapted to detect other respiratory pathogens, making it a flexible platform for future biosensing needs.

Journal Reference

Kumar J., Xu M., et al. (2025). Capacitive biosensor for rapid detection of avian (H5N1) influenza and E. coli in aerosols. ACS Sensors. DOI: 10.1021/acssensors.4c03087, https://pubs.acs.org/doi/10.1021/acssensors.4c03087