Microplastics, tiny plastic particles often too small to see, have become a significant environmental concern found in our air, soil, and water. Measuring their presence is crucial for directing cleanup efforts, yet current detection methods are often slow, costly, or overly complex. In a groundbreaking study published in ACS Sensors, researchers have introduced a novel living sensor that attaches to plastic and generates green fluorescence, allowing for the quick identification of microplastics in real-world water samples.
Traditionally, scientists have relied on advanced microscopy or analytical tools like infrared and Raman spectroscopy to detect microplastics in water. While these techniques are accurate, they involve multiple steps for sample preparation and can be pretty time-consuming. In an effort to simplify the process, a team led by Song Lin Chua has engineered a living microplastics sensor using the bacterium Pseudomonas aeruginosa, which is commonly found in the environment and capable of forming biofilms on plastic surfaces.
The researchers modified a non-infectious strain of P. aeruginosa by incorporating two genes: one that activates when the bacterium comes into contact with plastic and another that produces a green-fluorescent protein in response. Laboratory tests revealed that the engineered bacteria glowed in the presence of various plastics, such as polyethylene terephthalate (PET) and polystyrene, while showing no fluorescence with materials like glass and sand. Remarkably, fluorescence could be detected within just three hours, and the modified bacteria remained active for up to three days when stored at refrigerator temperatures.
To further assess the biosensor’s practical applications, the team tested it in seawater obtained from a polluted city waterway. After filtering and treating the seawater to remove organic matter, they introduced the engineered bacteria. The fluorescence intensity readings indicated the presence of up to 100 parts per million of microplastics. Subsequent analysis using Raman microspectroscopy confirmed that the detected microplastics were primarily biodegradable types, including polyacrylamide, polycaprolactone, and methyl cellulose, which the biosensor effectively identified.
“Our biosensor offers a fast, affordable, and sensitive method for detecting microplastics in environmental samples within hours,” says Chua. “By serving as a rapid screening tool, it could revolutionize large-scale monitoring initiatives and assist in identifying pollution hotspots for more detailed investigations.”
The researchers’ work received support from several funding bodies, including the Environment and Conservation Fund and the Health and Medical Research Fund, highlighting the growing commitment to tackling plastic pollution in our ecosystems.
