Biology Reference
In-Depth Information
Electrochemical methods are well suited for molecular diagnos-
ticsofmicroorganismsonthegenomicandproteomiclevel.Electro-
chemical reactions can be designed to produce a direct electronic
signal using a portable handheld and inexpensive electrochemical
analyzer (AndCare, PalmSens, DropSens etc.) that is commercially
available in the market, without any expensive signal transduction
equipment [4].
Numerous electrochemical platforms have been developed for
DNA detection, including direct electrochemistry of the DNA
bases [5], electrochemistry of different polymer-modified screen-
printed chips [6], electrochemistry of DNA-specific redox indicator
moleculesorenzymes[7,8],electrochemistryofsignalamplification
with nanoparticles (NPs) such as gold, silver or magnetic particles
[9, 10], and dsDNA
π
-stacked mediated charge transport chemistry
[4, 7, 11, 12].
A genosensor for bacterial detection should possess the fol-
lowing criteria: sensitive (able to detect the bacterium in a small
sample), specific (able to distinguish the target from non-target
strains), precise, rapid and able to perform direct measurement
without pre-enrichment. In addition, it would be desirable if
the genosensor is portable or handheld, affordable and can be
performed even by untrained personnel.
Biosensors for bacterial detection involve biological recognition
components such as presence of the biomarkers, nucleic acid,
antibodies or aptamer attached on a transducer. However, in this
chapter, bacterial nucleicacid willbedescribed in detail [13].
Electrochemical genosensors for detection of various bacterial
specieshavebeendescribedinRefs.8and13-19.Reliabledetection
assays have been developed for pathogenic bacteria such as
Salmonella
sp,
E. coli
0157:H7,
Staphylococcus aureus
and
Vibrio
cholerae
thatcausemajorworldwidefoodborneoutbreaks[8,13,16,
19, 20].
The general scheme of a genosensor assay development starts
with the immobilization of the specific nucleic acid sequence
(“probe”) on the transducer surface. The presence of the com-
plementary sequence (“target”) in the sample is recognized and
captured by the probe through hybridization.
