Researchers have developed a microbial biosensor that fluoresces in the presence of microplastics, offering a potential low-cost, rapid alternative to conventional detection techniques. The work couples a genetically engineered strain of Pseudomonas aeruginosa with Raman microspectroscopy to detect microplastic concentrations in environmental water samples.
Conventional approaches such as Fourier-transform infrared (FTIR) spectroscopy and Raman microspectroscopy provide accurate results, but require extensive sample preparation, trained operators, and hours to days of analysis. By contrast, the engineered bacterium binds to plastic surfaces and produces a green fluorescent protein (GFP) signal within three hours. The biosensor demonstrated a detection limit of 1 ng/mL – more sensitive than existing methods – and produced a fluorescence signal that correlated linearly with microplastic concentration, enabling calibration for quantification.
Tests showed that the biosensor responded to a wide range of plastics, including PET, polystyrene, PVC, and nylon, and functioned across conditions relevant to environmental monitoring, including seawater, freshwater, and saline media. It remained stable for up to three days under refrigeration and reusable across multiple detection cycles, retaining more than 85 percent of its fluorescence after three rounds. However, performance decreased under strongly acidic conditions (pH 5), while remaining robust at neutral to mildly alkaline pH values.
In pilot trials with seawater collected from urban Hong Kong waterfronts, the biosensor detected concentrations equivalent to nearly 230 μg/mL. Raman microspectroscopy confirmed that the plastics were mainly biodegradable types such as polyacrylamide, polycaprolactone, and methyl cellulose. A direct comparison underscored its advantages: while microscopic enumeration and Raman spectroscopy required 6–12 hours of preparation and analysis, the biosensor delivered comparable detection in just three hours at a fraction of the cost.
“Our biosensor offers a fast, affordable and sensitive way to detect microplastics in environmental samples within hours,” said lead author Song Lin Chua in a press release. “By acting as a rapid screening tool, it could transform large-scale monitoring efforts and help pinpoint pollution hotspots for more detailed analysis.”
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