August 17, 2025

Imagine tiny living machines that can smell chemicals and send electric signals directly to your devices! A team from Imperial College London and Zhejiang University did just that by creating smart bacteria-based biosensors. Using powerful genetic engineering tricks, they transformed Escherichia coli bacteria into living, self-powered chemical detectors. Traditional biosensors often have problems—they can be expensive, delicate, and slow, especially in dirty or complex environments. But these new whole-cell biosensors use living bacteria that can repair themselves and work well even in messy samples. The exciting twist? These bacteria send out electrical signals instead of just light signals. That makes it easy to connect them to simple, low-cost electronics for real-world use. Here’s the magic they built: Three biosensor modules live inside these tiny microbes. The first detects special chemicals like sugar or mercury. The second boosts the signals to make them clear. The last produces special molecules called phenazines. These phenazines trigger an electrical current when touching an electrode, showing the chemical’s presence! Their first sensor senses arabinose, a plant sugar often found in labs. When arabinose meets the bacteria, they produce phenazine-1-carboxylic acid. This molecule touches an electrode, making a current that grows as sugar rises. The answer comes in about two hours—quick and easy! Next, they tackled a dangerous toxin: mercury. Since mercury is tiny in water, the bacteria got a genetic amplifier. When mercury binds a protein named MerR, bacteria flood phenazine production. Even just 25 nanomoles of mercury—below the World Health Organization’s safety limit—caused a clear electrical signal in three hours! They didn’t stop there. The team also created an 'AND' logic gate inside the bacteria, so it signals only when two chemicals show up together—a smarter, more selective sensor! As the researchers proudly say, this is a proof of concept showing living, electronic biosensors that can find harmful compounds, process signals inside, and give data in electric form. This breakthrough opens the door to cheap, portable biosensors for quick and reliable field detection. Science meets life in the tiniest package possible!

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Tags: Bioelectronic devices, Genetically engineered bacteria, Biosensors, Escherichia coli, Chemical sensors, Electrochemistry,