Characterizing a Silver Nanoparticle-Based Electrochemical Biosensor for Shiga Toxin Detection

Shiga toxins (1, 2) regularly cause outbreaks and food recalls and pose a significant health risk to the infected population. Therefore, new reliable tools are needed to rapidly detect Shiga toxin cost-effectively in food, water, and wastewater before human consumption. Enzyme immunoassay and polymerase chain reaction approaches are the gold standard detection methods for the Shiga toxin. However, these methods require expensive instruments along with expensive reagents, which makes them hard to convert into point-of-use and low-cost systems. This study introduces an electrochemical biosensing method that utilizes silver nanoparticles (AgNPs) as electrochemical tags and commercially available low-cost screen-printed carbon electrodes for detection. This study introduces the modification of reference electrodes on commercially available screen-printed carbon electrodes to detect AgNPs dissolved in nitric acid. This biosensor achieved a 2 ng/mL lowest measured concentration for Shiga toxin-1 in less than 3 h. These biosensor results also showed that the AgNP-based sensor has better linearity (for graph between peak current vs concentration) and lower standard deviation compared to gold nanoparticles (AuNP)-based electrochemical biosensors.