DNA/RNA aptamer biosensors – a new frontier for environmental virus surveillance

In the wake of recent global health crises, environmental surveillance has become a vital “early warning system.”

By testing wastewater, air and high-traffic surfaces, scientists can detect the presence of a virus within a community long before a surge in hospital patients confirms an outbreak. However, traditionally, this monitoring has relied on slow, laboratory-heavy processes.

A new review led by researchers at the Dalian University of Technology suggests that a shift towards aptamer-based biosensors could bridge the gap between high-tech laboratory accuracy and real-world portability.

What are aptamers?

Aptamers are short, single strands of DNA or RNA engineered to bind to specific targets – such as a viral protein – with incredible precision.

In many ways, they act like antibodies, which are the body’s natural defense molecules used in many diagnostic tests.

However, aptamers have several technical advantages for environmental work.

They are fully synthetic, making them easier and cheaper to manufacture than antibodies. They are also significantly more stable at high temperatures and can be easily modified to fit into different types of portable sensors.

These features make them ideal for "in the field" use, where a sensor might have to endure fluctuating weather or be used far away from a climate-controlled lab.

“Reliable viral detection underpins nearly every public health response, from patient diagnosis to outbreak surveillance,” says Jiuxing Li, the study’s corresponding author.

“Our review shows that aptamer-based biosensors are rapidly closing the gap between laboratory accuracy and real-world usability.”

Moving beyond the lab

The researchers highlight the limitations of current "gold standard" methods like PCR (polymerase chain reaction).

While PCR is highly sensitive, it usually requires expensive equipment and trained personnel. This makes it difficult to use for rapid testing across large geographic areas.

Aptamers seek to solve this through a process called SELEX (systematic evolution of ligands by exponential enrichment).

Think of this as a "survival of the fittest" laboratory process where billions of random DNA or RNA sequences are tested against a virus. Only the ones that bind most tightly are kept and copied.

Because this process is synthetic, developers can quickly adapt the sequences if a virus evolves or if a new threat emerges.

This allows for a "programmable" approach to environmental safety.

Technology for the real world

Once an aptamer is selected, it can be integrated into various sensor designs:

• Electrochemical sensors: these translate a virus binding to the aptamer into an electrical signal. They are often small enough to be battery-powered and handheld

• Optical platforms: these use light or colour changes (sometimes readable by a smartphone camera) to show the presence of a virus

• Nanomaterials: by combining aptamers with gold or carbon nanoparticles, scientists can amplify signals, allowing them to detect viruses even at very low concentrations in large water systems.

“These biosensors can be designed for rapid testing outside traditional laboratories,” notes co-corresponding author Meng Liu. 

“Some platforms can deliver results in minutes, require minimal sample preparation and operate with portable or handheld devices.”

From wastewater to food safety

The environmental applications for this technology are vast.

In water systems, aptamer sensors could provide constant monitoring of wastewater to track viral spread across entire cities. In hospitals or transport hubs like airports, air and surface sensors could guide cleaning protocols or ventilation adjustments in real-time, stopping "hotspots" before they grow.

The technology also has major implications for food safety. Rapidly detecting viral contamination along a supply chain could prevent widespread food poisoning or livestock disease outbreaks, particularly when traditional testing would cause days of delay.

The path forward

Despite the potential, some hurdles remain.

Testing "dirty" environmental samples – like muddy water or complex aerosols – is much harder than testing a clean sample in a lab.

The researchers argue that for these sensors to become routine, they must be validated on a large scale and integrated into digital reporting systems. This way data from thousands of sites can be managed automatically.

As health systems around the world plan for future threats, aptamer-based biosensors are poised to become a critical component of our global early warning infrastructure, providing the ability to detect viral risks wherever they emerge.