Nanosensors - Nanotechnologies for Water Environment Applications - page 435

microorganism in water and other environmental matrices. A recently published review
of literature related to biosensors for pathogen detection reported that 38% of the studies
were focused on food borne pathogens while 16% were focused on waterborne
pathogens (Lazcka et al., 2007). Because the term nano-sensors is recent, such market
trends do not differentiate based on scale. The developed biosensors are for a number of
water and food borne pathogens in particular E. coli O157:H7 , Campylobacter ,
Cryptosporidium , Legionella , Listeria , and Salmonella . Similarly a comparison of
major techniques for pathogen detection (based on the number of publications) showed
biosensors stands fourth and has a huge growth potential in the future. Market analysis
of biosensors focusing on medical, military, food, and environmental applications
indicated a $563 million market size and a potential growth rate of 4.5% (Alocilja and
Radke, 2003). However, a separate market assessment for the water industry alone is
seldom available. There is also a lack of regulation to directly measure the pathogens
because of the cost associated with it. This may be due to the relatively better results
obtained by the treatment-based approach alone and the extensive use of bottled and
mineral water for drinking purposes. In the United States, for example, waterborne
disease outbreaks were responsible for 403,000 illnesses between 1991 and 2002 and
resulted in 50 deaths (Craun et al., 2006). The comparatively high percentage of
biosensor applications for food industry is due to the development of portable detection
platforms (Arora et al., 2006). Considering the diversity and complexity of
environmental samples, a broad range of environmental applications, and lower
economical benefits, the slower development pace of portable biosensors for water
industry makes sense. Presently there is a need of portable biosensors for the rapid
detection of waterborne pathogen due to the increasing cases of waterborne disease
outbreaks. However, portable devices must address the issue of how to
process/concentrate the large volumes of water before the biosensors can be useful.

13.12 Conclusions

Over recent years, considerable effort has been devoted to the study and
development of micro- and nanoscale biosensors. The application of sensors for the
water industry is constantly increasing, due to the high risk of disease outbreaks.
However, sample complexity, lower economical benefit, and lack of portability are
limiting the widespread use of biosensor for water industry. Specificity, sensitivity,
speed, ruggedness and the ability to handle large volumes of water are the key points for
assay applicable to waterborne pathogen detection. The progresses in micro- and
nanotechnology have high potential in enabling novel biosensor technologies with
improved characteristics required for water industry. Nanoparticles, in particular gold
particles, quantum dots (QDs), and organic dye doped silica particles show great
promise for highly sensitive pathogen detection. Approaches that eliminate the need for
target labeling e.g., nanocantilevers, surface plasmon resonance, and