Abstract
Current bacterial detection techniques are relatively slow, require bulky instrumentation, and usually require some form of specialized training. The gold standard for bacterial detection is culture testing, which can take several days to receive a viable result. Therefore, simpler detection techniques that are both fast and sensitive could greatly improve bacterial detection and identification. Here, we present a new method for the detection of the bacteria Helicobacter hepaticus using whispering-gallery mode (WGM) optical microcavity-based sensors. Due to minimal reflection losses and low material adsorption, WGM-based sensors have ultra-high quality factors, resulting in high-sensitivity sensor devices. In this study, we have shown that bacteria can be non-specifically detected using WGM optical microcavity-based sensors. The minimum detection for the device was 1 × 104 cells/mL, and the minimum time of detection was found to be 750 s. Given that a cell density as low as 1 × 103 cells/mL for Helicobacter hepaticus can cause infection, the limit of detection shown here would be useful for most levels where Helicobacter hepaticus is biologically relevant. This study suggests a new approach for H. hepaticus detection using label-free optical sensors that is faster than, and potentially as sensitive as, standard techniques.
Highlights
Helicobacter hepaticus (H. hepaticus) is a bacterium that causes chronic hepatitis and liver cancer in mice [1]
For the first time, we demonstrate the capability of the whispering-gallery mode (WGM) optical microcavity-based sensor platform for the bacterial detection of H. hepaticus at relevant concentrations, and demonstrate that this detection is much faster than standard techniques
This study establishes a proof of concept for the detection of H. hepaticus using a WGM optical microcavity-based sensor platform
Summary
Helicobacter hepaticus (H. hepaticus) is a bacterium that causes chronic hepatitis and liver cancer in mice [1]. Changes in the refractive index of an optical field interacting with the analyte These sensors, which include Surface Plasmon Resonance (SPR) and Whispering Gallery Mode (WGM) optical devices, have become more popular in recent years due to their speed, sensitivity, and label-free sensing properties [7,23,24]. If an analyte adsorbs onto the device’s surface, the circulating optical field experiences a change in the effective refractive index, causing an extremely rapid and detectable shift in the resonant frequency and amplitude of response This is, why WGM optical microcavities are ultra-sensitive and is the basis for their sensing capabilities [28]. For the first time, we demonstrate the capability of the WGM optical microcavity-based sensor platform for the bacterial detection of H. hepaticus at relevant concentrations, and demonstrate that this detection is much faster than standard techniques
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