IIT Guwahati: Disposable biosensor selectively detects alcohol

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 research has been published in the journal ACS Applied Materials & Interfaces.

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 miniaturised device allowed a decrease in response time to about 10 seconds,” says Dr Pranab Goswami of the Department of Biosciences and Bioengineering, IIT Guwahati, who led the study.

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. This selectivity was also established by the group.

The magnitude of the surge in potential when the device is sprayed with ethanol could be correlated with ethanol concentrations (0.001 to 20%). The device has a detection limit of 0.13%.

“The paper-based device is prepared in a disposable format and can be used only once,” says Sharbani Kaushik, who is at the Centre for Energy, IIT Guwahati and is the first author of the paper. The team plans to make the biosensor commercially available.