Rapid detection of pathogens like bacteria and viruses is of great importance for monitoring water and food quality, the early detection of diseases, countering bioterrorism attacks, and other applications. Successful detection requires the manipulation and capture pathogenic particles for further analysis. This work reports a synergistic approach for the concentration, detection and kinetic monitoring of pathogens through the integration of nanostructured dielectrophoresis (DEP) with nanotag-labelled Surface Enhanced Raman Scattering (SERS). Vertically Aligned Carbon Nanofibers (VACNFs) at the bottom of a microfluidic chip was used to effectively capture and concentrate nanotag-labelled <i>E. coli</i> cells onto an active area at which the Raman laser probe was focused. The SERS nanotags were based on iron oxide-gold (IO-Au) core-shell nanoovals were coated with QSY21 Raman reporters and attached to <i>E. coli</i> cells through specific immunochemistry. The SERS signal was measured with both a confocal Raman microscope and a portable Raman probe during DEP capture, and was fully validated with fluorescence microscopy measurements under all DEP conditions. The combination of the greatly enhanced Raman signal by the SERS nanotags and the effective DEP concentration significantly improved the detection limit as low as 210 cfu/mL and speed of detection of only ~50 s. The SERS measurements were sensitive enough to detect a single bacterium. These results demonstrate the potential to develop a compact portable system for rapid and highly sensitive detection of specific pathogens. Such system is reusable, requires minimum sample preparation, and is ideal for field applications.

Integration of nanostructured dielectrophoretic device and surface-enhanced Raman probe for highly sensitive rapid bacteria detection

249th National Meeting (2015)

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