• 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.