Chemical Engineering

New biosensor detects and eliminates bacteria

This new Chinese Biosensor is able to detect and eliminate E. Coli, making water safer

By: Joseph Park, Journalist

March 10, 2025

How Silver-ion Antimicrobial Technology Fights Against Bacteria.

What is a biosensor?

A biosensor is a device that uses living organisms such as enzymes and antibodies to detect substances such as chemicals. This is especially used to detect harmful chemicals and substances in water or food. There are 6 types of biosensors: resonant biosensors, lectin-based sensors, optical detection, thermal detection, ion-sensitive, and electrochemical biosensors. These different types of sensors are used for various situations, and all have advantages and disadvantages. The most common being electrochemcial biosensors which are usually used in diabetes diagnosis. Other biosensors have real-world uses as well. Lectin-based biosensors are the best at measuring carbohydrates, alcohols, and acids for food labels. In our case, the biosensor is glucose-based and is used to remove E. coli from water.

The Chinese Biosensor

The biosensor uses an enzyme-based biofuel cell, antibodies called aptamers, and a bacterial elimination mechanism to make water decontamination faster and easier. The biosensor operates in 3 components. The first type of biofuel cell, known as an enzymatic biofuel cell (EBFC), generates power for the sensor by utilizing enzymes to produce electricity through biochemical reactions. It employs glucose oxidase (GOx) to break down glucose, which results in the production of electrons (electricity) and hydrogen peroxide. However, this enzyme can lose stability over time. To solve this, the team put it inside a hollow metal-organic framework (MOF) called ZIF-8. This helps protect it from damage over time and keeps it working well in different conditions. Aptamers, which are short strands of DNA, play a crucial role in the biosensor by specifically binding to parts of the exterior of E. coli. According to the team, these antibodies are connected to silver nanoparticles (AgNPs). Until E. coli is detected, the AgNPs prevent glucose from reaching the enzyme. 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 the bacteria’s presence. The third component consists of a mechanism aimed at eliminating bacteria, specifically targeting E. coli cells detected by the sensor. This is accomplished through a precise dose of hydrogen peroxide, a byproduct produced by the sensor’s biofuel cell. When hydrogen peroxide is applied, it oxidizes the silver nanoparticles and releases silver ions (Ag+), which are well-known for their antibacterial properties. Remarkably, these silver ions can eradicate 99.9% of bacteria within a few hours.