Biology Reference
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protein-protein interaction as well as the proteolysis of viral replication
in living cells. 90 It has the potential to be used to detect pathogenic
bacteria. 97
FRET systems have been used to detect pathogens or toxins. 98,99 How-
ever, there are no studies that have solely used a FRET system to detect
waterborne pathogens from water sources. Several biosensor platforms are
based on FRET-like systems and will be discussed in the biosensor section
later in the chapter.
8.2.3.9. Microfluidics
Microfluidic technology emerged in the 1980s. It allows a reaction to take
place on the surface of very small solid material. The best examples are
inkjet print heads. The technology deals with the behavior, precise control,
and manipulation of fluids that are geometrically constrained to a small,
typically submillimeter, scale. Micropumps supply fluids in a continuous
manner or are used for dosing. Microvalves determine the flow direction
or the mode of movement of pumped liquids. This technology has allowed
research in molecular biology to miniaturize some processes and produce
lab-on-chip or DNA-chip technology. This means that molecular biology
techniques such as DNA isolation and PCR from samples could be min-
iaturized and automated to accomplish detection in far less time and labor
than macrotechniques. 44
Han et al. 100 showed that E. coli could be detected at less than 40 cfu mL −1
for viable cells in pure culture using latex immunoagglutination coupled
with a microfluidic technology. Microfluidics has also been applied to
water samples, whereby Chow and Du 101 devised a microfluidic device that
allowed them to trap bacterial cells from a continuous flow stream and dif-
ferentiate between E. coli and Enterococcus faecalis. Similarly, Taguchi et al. 102
used a microfluidic device to trap Cryptosporidium oocysts, which were then
subjected to automated fluorescein isothiocyanate (FITC) labeling and
imaging with a detection limit of 36oocystsmL −1 . Ramalingam et al. 103
designed a real-time PCR-based microfluidic array chip that was able to
simultaneously detect four waterborne pathogens, Pseudomonas aeruginosa ,
Aeromonas hydrophila , Klebsiella pneumonia , and Staphylococcus aureus by using
a prototype real-time machine. It is still unknown whether this technol-
ogy can be reliably applied to raw water samples, but it holds much prom-
ise as a technology that can reduce the detection time and improve risk
assessment. Recently, Chow and Du 101 fabricated a dielectrophoresis-based
microfluidic channel to trap bacteria from water samples. They could easily
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