Abstract
Bacterial contamination of water sources (e.g., lakes, rivers and springs) from waterborne bacteria is a crucial water safety issue and its prevention is of the utmost significance since it threatens the health and well-being of wildlife, livestock, and human populations and can lead to serious illness and even death. Rapid and multiplexed measurement of such waterborne pathogens is vital and the challenge is to instantly detect in these liquid samples different types of pathogens with high sensitivity and specificity. In this work, we propose a biosensing system in which the bacteria are labelled with streptavidin coated magnetic markers (MPs—magnetic particles) forming compounds (MLBs—magnetically labelled bacteria). Video microscopy in combination with a particle tracking software are used for their detection and quantification. When the liquid containing the MLBs is introduced into the developed, microfluidic platform, the MLBs are accelerated towards the outlet by means of a magnetic field gradient generated by integrated microconductors, which are sequentially switched ON and OFF by a microcontroller. The velocities of the MLBs and that of reference MPs, suspended in the same liquid in a parallel reference microfluidic channel, are calculated and compared in real time by a digital camera mounted on a conventional optical microscope in combination with a particle trajectory tracking software. The MLBs will be slower than the reference MPs due to the enhanced Stokes’ drag force exerted on them, resulting from their greater volume and altered hydrodynamic shape. The results of the investigation showed that the parameters obtained from this method emerged as reliable predictors for E. coli concentrations.
Highlights
Microbial pathogen detection is of utmost priority for water quality control since microbial contamination threatens the health and well-being of wildlife, livestock, and human populations and can lead to serious illness and even death
We present the proof of concept for a biosensing system able to monitor the presence of magnetically labeled E. coli and provide same day information on the bacterial concentration in the water sample
The proposed platform is designed in such a manner so as to be applied for the quantification of E. coli and for any other disease-causing micro-agent, if one uses the appropriate antibodies and magnetic particles with a size relative to the analyte to be detected
Summary
Microbial pathogen detection is of utmost priority for water quality control since microbial contamination threatens the health and well-being of wildlife, livestock, and human populations and can lead to serious illness and even death. Traditional water monitoring techniques are typically still based on laboratory analyses of representative field-collected samples; this necessitates considerable effort and expense, and the sample may change before analysis [1]. There is an increasing demand of robust and efficient techniques of contaminants detection and of monitoring devices that save tremendous amounts of time, reagent, and sample if it is installed at contaminated sites. The current state of the art often fails to address same day measurements combined with multiple detection analyses and the Sensors 2018, 18, 2250; doi:10.3390/s18072250 www.mdpi.com/journal/sensors
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