Biology Reference
In-Depth Information
re piezoelectrical based sensors that are operated by applying an
oscillating voltage at the resonant frequency of the crystal, and
measuringthechangeinresonantfrequencywhenthetargetanalyte
interacts with the sensing surface [32]. The QCM method has
been adopted by several groups to detect the DNA hybridization
reaction because of its great sensitivity as a mass sensor capable of
measuring subnanogrammass changes [33-34].
Electrochemical biosensors measure the electrochemical
changes that occur when biochemical element interacts with a
sensing surface of the detecting electrode. The electrical changes
can be based on a change in the measured voltage between the
electrodes (potentiometric), a change in the measured current at a
given applied voltage (amperometric), or a change in the ability of
the sensing material to transport charge (conductometric) [35].
13.3 Electrochemical Nucleic Acid Biosensors
Electrochemical nucleic acid biosensors are based on electro-
chemical transduction of the hybridization event and show great
promisefordetectionofspecificgenesequencesrelatedtoinherited
and infectious diseases. Electrochemical detection of specific DNA
sequences has an advantage in reducing the size of the total
detection system [36]. The advantages of electrochemical nucleic
acid biosensors include potential of miniaturization, short response
time, ease of use, low cost, and compatibility with microfabrication
techniques [37].
The aim of electrochemical genosensing techniques is to design
DNA systems allowing early diagnosis of microorganisms and poly-
morphisms in clinical analysis. For this purpose several techniques
have been investigated based on recognition of DNA hybridization,
by using electroactive labels, dye molecules, nanoparticles, or label-
free methods.
Electrochemical DNA biosensors are divided into two main
groups:
1. Label-basedDNA hybridizationdetection method
2. Label-free DNAhybridization detection method
