Electromechanical detection of pathogens with self-assembled nucleic acid biosensors

Monitoring of water samples in remote locations and the developing world is crucial to protect people from infectious diseases primary caused by enteric pathogens. Routine pathogen detection, which is usually based on cell cultivation methods, is labor intense and time consuming. Some pathogens may cause diseases with rapid-evolution symptoms. Therefore, fast, sensitive and reliable detection of pathogen contamination is of great significance. Biosensor technologies are currently under intense investigation for detecting pathogens responsible for diseases in various fields. For point of sample applications, the detection platform should be cost-effective, fast, sensitive, easy to use, stable under a wide range of operating conditions, and portable. Nucleic acid-based biosensors show great potential for integration in a lab-on-a-chip (LOC) for selective and sensitive detection of target microorganisms. Especially schemes employing electromechanical signal transduction are simple and straightforward, e.g. quartz crystal microbalances (QCM). In this work, we show two different QCM-based detection schemes: a proof-of-concept study for indirect detection of Escherichia coli (E. coli) via matching of characteristic DNA sequences and a direct capture biosensor utilizing an E. coli specific aptamer.