Modular Biosensors

Why in News?

Recently, Researchers from Imperial College London and Zhejiang University developed genetically engineered bacteria, a step towards building cheap and programmable bioelectronic devices.

• Biosensors – Analytical devices that consist of a combination of biological detecting elements, like a sensor system and a transducer.
• It can be defined as self-sufficient integrated devices that can provide specific qualitative or semi-quantitative analytical information.
• It uses a biological recognition element that is in direct spatial contact with a transduction element.
• Whole Cell biosensors – It is analytical devices that utilize living microorganisms to detect and quantify specific biological or chemical substances.
• It leverages the natural biological response of cells to changes in their environment, converting biochemical signals into measurable electrical signals.
• It can maintain and repair itself & operate inside contaminated samples.
• Issues with Traditional biosensors – It is based on enzymes, are often fragile, costly and have a slow response time in complex environments.
• Modular biosensor – It could sense the presence of specific compounds and convert that into an electrical signal, which is compatible with low-cost electronics.
• Source organisms – The term used genetically engineered Escherichia coli (E coli) bacteria as containers to host the biosensor modules. These microbes hosted 3 biosensor modules.
  • Sensing module – It detected a target chemical through specific molecular regulators.
  • Information Processing Module – It amplified or processed the signal.
  • Output module – It produced phenazines, nitrogen-containing organic molecules that can be measured using an electrochemical technique called voltammetry.
• Two sensors are built by researchers
  • 1^st sensors - Arabinose – A simple plant sugar often used in lab media.
  • A sample containing the sugar came in contact with the bacteria, and the cells started producing phenazine-1-carboxylic acid.
  • When this molecule touched the electrode, the latter produced a current that rose with the sugar level.
  • The signal appeared in roughly 2 hours.
  • 2^nd sensor – Mercury ions – These ions are present only in trace quantities in real-world water.
  • The mercury bound with a protein called MerR, triggering the production of a polymerase that pushed the phenazine production pathway into overdrive.
  • 25 nanomoles of mercury, which is below the WHO safety limit, produced a readable current within 3 hours.

• Logic gate—The ‘AND’ logic gate inside E. coli, produced a signal only when two specific molecules were present together.
• It is established a proof of concept of a living, electronically integrated biosensor capable of detecting compounds in its surroundings, processing the signals, and supplying data.

Reference

The Hindu| Modular Biosensor