Benefits of Nanotechnology for the Environment - Nanotechnology and Human Health - page 135

Immunochemistry* is actively involved in the operation of the biosensor
technologies. It involves techniques such as immunoaffinity chromatogra-
phy † and immunoassay ‡ [20]. Sample preparations based on immunoaffinity
take advantage of the attraction between an antibody and a specific analyte
[20]. By rinsing a water sample over an antibody-treated surface, chemists
can isolate particular compounds adhering to the antibody molecules. The
isolated compound is then eluted from the immobilized antibody and ana-
lyzed, using chromatography or immunoassay techniques [20]. Antibodies
can be produced synthetically for a variety of organic pollutants.
An important example of a novel water monitoring nanotechnology, based
on an immunoassay technique, is the Automated Water Analyzer Computer
Supported System (AWACSS). It was developed by researchers from the
Corporate Technology Division of Siemens AG in Erlangen (Germany), in col-
laboration with the Karlsruhe Water Technology Center and the University
of Tübingen [21]. The project was financed by the European Commission
(EC) and technically designed by Siemens. AWACSS has the size of a suit-
case and it can simultaneously test several samples and send the results to
a central server [21]. The system is able, within less than 18 min, to check for
32 different substances, ranging from hormones to pesticides and antibiotics.
The device can detect very low concentrations (i.e., <1 μg L -1 ) [21].
The key component of AWACSS is an array of nanostructured biochips,
which can capture molecules of environmental pollutants [21]. The water
sample is first mixed with antibodies that are marked with a fluorescent pig-
ment (e.g., Cy5.5, Alexa680, or quantum dots). If the sample contains specific
organic molecules, the antibodies attach to them [21]. Then, a pump propels
the liquid across the array of small glass biochips, each coated with a layer of
captor molecules. These molecules capture the antibodies (as they are bound
to the toxins) and the remaining particles are rinsed from the chips [21]. A
concentrated light source is used to cause the captured antibodies to glow,
making them detectable by an optical sensor [21].
7.3.3 Summary and Conclusions
As was shown in previous sections, nanotechnology contributes to the field
of environmental monitoring through the development of sensing alterna-
tives with enhanced functionality. The nanostructured SSGs are simple to
use, technologically more effective, and cheaper than their conventional
counterparts. Current research is focused on the development of a new gen-
eration of sensors, incorporating semiconducting nanowires, nanobelts, or
* Immunochemistry is a branch of chemistry that involves the study of the reactions and com-
ponents of the immune system.
† Imunoaffinity chromatography is a column chromatography method using antibody-anti-
gen reactions to purify or detect substances.
‡ An immunoassay is a biochemical test that measures the concentration of a substance in a
liquid, using the reaction of an antibody (or antibodies) to its antigen.