- There is a lot of interest now in developing biosensors that have short response time, selectivity and sensitivity.
- Researchers from IIT Guwahati have developed a paper-based biosensor that can detect ethanol.
- The short response time of about 10 seconds to detect ethanol and the range of concentrations to which the response was proportional make the biosensor particularly attractive.
- With available hand-held devices such as breath analysers being non-specific, non-selective, requiring extra power sources, being expensive to fabricate and so on, cheap and effective biosensors become necessary.
- The team fabricated the device using chromatography paper and patterned anodic and cathodic zones on it.
- A silk-based nano-biocomposite layer was fixed in the anodic zone, and when it was half-dry, the team coated it with cyanobacteria — a group of photosynthetic bacteria.
- The bacteria could stay alive and conduct their metabolic activities because of the silk-based composite.
- The cell membrane of cyanobacteria contains electron transfer proteins that can capture electrons from donors and transfer them to electron acceptors.
- When sprayed on the cyanobacterial layer, ethanol interacts with the cell membrane causing it to degrade and release the electron transfer proteins, which come in contact with the anode.
- They transfer electrons to the anode, causing a potential difference between the anode and the cathode.
- The researchers confirm that this potential surge increases with increase in the concentration of ethanol. Further, the response of the device to ethanol and methanol was markedly different.
- The paper-based device is prepared in a disposable format and can be used only once.
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