Low-complexity detection of infectious diseases with high sensitivity and specificity is urgently needed, especially in resource-limited settings. Optofluidic integration combines clinical sample preparation with optical sensing on a single chip-scale system, enabling the direct, amplification-free detection of single RNA from Ebola viruses. The optofluidic system fulfills all key requirements for chip-based clinical analysis, including a low limit of detection, wide dynamic range, and the ability to detect multiple pathogens simultaneously.
Illustration of a virus and blood cells (Shutterstock) |
The recent Ebola and Zika outbreaks [1, 2] have made it clear that viral infections continue to pose diverse and widespread threats to humanity. Resource-limited settings, in particular, call for diagnostic devices and technologies that are robust and feature relatively low complexity for easy handling by potentially unskilled personnel. At the same time, such instruments need to fulfill all the technical requirements for accurate and reliable diagnosis. These include a limit of detection and dynamic range that are compatible with clinically observed viral loads as well as the ability to carry out multiplexed differential detection by screening simultaneously for several pathogens with similar clinical symptoms.
For the last two decades, the lab-on-chip approach, which features a small footprint and sample volume, has been considered as a promising candidate for the next generation low-complexity medical diagnostics [4]. Among all the approaches, optofluidics, which integrates optics and microfluidics in the same platform, has received increased attention [5, 6]. Microfluidics is ideal for performing biological sample processing on a chip-scale level and leads to miniaturization and simplification of the current diagnostic system. If it can be integrated with an optical sensing/read-out platform that enables high detection sensitivity down to the single pathogen level, an analytic system for which nucleic acid amplification is no longer needed becomes possible.
Figure 2. (a) Schematic of multi-mode interferometer (MMI) waveguide intersecting with liquid-core ARROW. (b) Excitation spots, 9 (blue), 8 (green), and 7 (red), generated by the MMI at wavelength of 488nm, 553nm and 633nm, respectively. (c) Optical signal detected from various labelled single virus particles. (Adapted from Ozcelik et al., 2016 [14])
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Read more: Ebola Virus - Amplification-free direct detection on a hybrid optofluidic platform
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