Electrochemical nucleic acid-based sensors for detection of Escherichia coli and Shiga toxin-producing E. coli-Review of the recent developments

Escherichia coli are a group of bacteria that are a natural part of the intestinal flora of warm-blooded animals, including humans. Most E. coli are nonpathogenic and essential for the normal function of a healthy intestine. However, certain types, such as Shiga toxin-producing E. coli (STEC), which is a foodborne pathogen, can cause a life-threatening illness. The development of point-of-care devices for the rapid detection of E. coli is of significant interest with regard to ensuring food safety. The most suitable way to distinguish between generic E. coli and STEC is by using nucleic acid-based detection, focusing on the virulence factors. Electrochemical sensors based on nucleic acid recognition have attracted much attention in recent years for use in pathogenic bacteria detection. This review has summarized nucleic acid-based sensors for the detection of generic E. coli and STEC since 2015. First, the sequences of the genes used as recognition probes are discussed and compared to the most recent research regarding the specific detection of general E. coli and STEC. Subsequently, the collected literature regarding nucleic acid-based sensors is described and discussed. The traditional sensors were divided into four categories such as gold, indium tin oxide, carbon-based electrodes, and those using magnetic particles. Finally, we summarized the future trends in nucleic acid-based sensor development for E. coli and STEC including some examples of fully integrated devices.