The second is the use of antibodies called aptamers in the biosensor. These short strands of DNA can specifically bind to parts of the E. coli‘s exterior. According to the team, aptamers are linked to silver nanoparticles (AgNPs) which block glucose from reaching the enzyme until E. coli is detected.
When E. coli is present, the aptamer binds to it, triggering a reaction to the silica barrier, allowing glucose to reach the enzyme. The oxidation reaction produces electrons, generating an electrical signal confirming bacteria’s presence.
The third component is a bacterial elimination mechanism that kills any E. coli cells the sensor finds. This is achieved using a targeted dose of hydrogen peroxide, a byproduct of the sensor’s biofuel cell. This oxidizes the silver nanoparticles, releasing silver ions (Ag+) renowned for their antibacterial properties. They are so effective that they can kill 99.9% of bacteria in just a few hours.