Nanotechnology for Detection of Waterborne Pathogens - Waterborne Pathogens: Detection Methods and Applications - page 285

One example is iron oxide, which has been utilized as a contrast agent in
magnetic resonance imaging as well as the immunomagnetic separation of,
and detection of, numerous pathogens. Iron oxides are often synthesized via
alkaline precipitation of iron salts. Control of nanoparticle shape and mag-
netic properties is possible via different synthetic strategies, e.g. temperature,
choice of reagents, reaction times. 1
The heterogeneity of MNPs is one challenge in the further applica-
tion of these materials. Another is the difficulty in precisely controlling
the number of functional molecules added at an NP. Therefore, research
is required to develop improved ways to produce MNPs focusing on ensur-
ing precise composition, uniform surface modification, and reproducible
functionalization. 2
9.2.6. Carbon nanotubes
Vertically aligned carbon nanofibers (VACNFs) have received a lot of
research attention as one dimensional nanoscale electrodes for biosens-
ing since they offer high electrical and thermal conductivities, superior
mechanical strength, flexible surface chemistry, biocompatibility, and a wide
electrochemical potential window. Carbon nanotubes (CNTs) are an allo-
trope of carbon in which planar sheets of carbon atoms (graphene) are
rolled up into cylindrical tubes (a single walled CNT). Multiwalled CNTs
can also be formed. Typical sizes are 0.4-3 nm in diameter and 2-100 nm
in length.
CNTs are semiconductors with excellent electrical properties, and
this property is often exploited for signal amplification or transducers for
detection of pathogens. Another possible use for CNTs is the protection
of molecular probes, which could be particularly useful in the molecular
detection of pathogens in environmental matrices, where DNA probes can
easily be degraded. 14
In 2009, Arumugam reported an improved fabrication method for
VACNFs, 15 which is one of the main challenges for this type of nanotech-
nology. In addition to the problems of fabrication of CNTs, questions have
also been raised about their potential toxicity. 14
9.3. NANOTECHNOLOGY IN SAMPLE PROCESSING
Nanotechnology has not been extensively applied to the challenge
of waterborne pathogen sample processing. This section presents the exam-
ples found in the literature, which are mainly concerned with viruses and