K. Urmann, J. Bahnemann, Z. Chikneyan, L.M. Kasmaee, M.R. Hoffmann
California Institute of Technology,
Keywords: aptamers, biosensor, quartz crystal microbalance, pathogen detection
Summary:Infectious diseases, primarily caused by enteric pathogens, remain a major cause of death, especially in remote locations of the developing world. Routine monitoring of pathogen contaminations is therefore crucial. We seek to apply quartz crystal microbalances (QCM) functionalized with highly selective nucleic-acid capture probes to provide a cost-effective, fast, easy to use and portable biosensing platform. While traditional methods are usually based either on time-consuming bacterial culturing or laboratory-based assays, which require specialized equipment and trained staff, these nucleic-acid based QCM biosensors can enable sensitive and reliable real-time detection of various analytes associated with pathogen contaminations (e.g. secreted toxins, characteristic DNA sequences or whole bacteria cells). In combination with reusable substrates, implementation in microfluidic lab-on-chip (LOC) devices and the flexibility for tailoring analytical assays, electromechanical biosensing via miniaturized QCM systems is highly suitable for point of care applications. In this work, we show two different QCM-based detection schemes: a proof-of-concept study for indirect detection of Escherichia coli via matching of characteristic DNA sequences and a direct capture biosensor utilizing an E. coli specific aptamer. These nucleic acid-based biosensors provide further advantages, such as long shelf-life and reusability, when compared to assays employing more delicate capture probes, e.g. antibodies.