Biomedical Engineering Reference
In-Depth Information
21.2
Biosensors for Detection of Virus and Bacteria
21.2.1
Genosensors
21.2.1.1 DNA Chips and DNA Biosensors
For the visual detection of HBV, hepatitis C virus (HCV), and human immunodeficiency
virus type-1 (HIV-1) simultaneously, a qualitative DNA chip method, combining multiplex
and nested polymerase chain reaction (PCR) with arrayed anchored primer PCR and a
biotin-avidin alkaline phosphatase (Av-AP) indicator system, was developed. After pre-
treatment of infected blood samples and reverse transcription of the RNA virus genome,
PCR was performed in a single tube by using the outer primer pairs. In the second round,
nested multiplex PCR was performed on the DNA chip, on which the primers array had
already been prepared [69].
Genosensor technology relying on the use of carbon and gold electrodes is reviewed. The
key steps of each analytical procedure, namely DNA-probe immobilization, hybridization,
labeling, and electrochemical investigation of the surface, are discussed in detail with
separate sections devoted to label-free and newly emerging magnetic assays. Special
emphasis has been given to protocols that have been used with real DNA samples [70].
Current Strategies for Electrochemical Detection of DNA with Solid Electrodes
A review of current strategies aimed at detecting nucleic acids (NA) using NA-modified
solid electrodes reveals the versatility and potential of electrochemical detection in this
field. What emerged at the beginning of 1990s as a very promising detection system in
DNA technology is now resulting in the first commercial device. Many aspects of the
experimental design, for example, surface immobilization and detection schemes, are out-
lined and evaluated. Although most approaches use hybridization devices as the recog-
nized detection scheme, those not based on hybridization are also included [71].
Recent trends and challenges in the electrochemical methods for the detection of DNA
hybridization are reviewed. Electrochemistry has superior properties over the other existing
measurement systems because electrochemical biosensors can provide rapid, simple, and
low-cost on-field detection. Electrochemical measurement protocols are also suitable for mass
fabrication of miniaturized devices. Electrochemical detection of hybridization is mainly
based on the differences in the electrochemical behavior of the labels toward the hybridiza-
tion reaction on the electrode surface or in the solution. Basic criteria for electrochemical DNA
biosensor technology, and already commercialized products, are also introduced. [72].
Influenza A virus, which are further subtyped on the basis of antigenic differences in exter-
nal hemagglutinin and neuraminidase glycoproteins, and Influenza B virus are prominent
among the viral causes of respiratory diseases and can cause a wide spectrum of illness. Each
year these virus are responsible for recurrent epidemics, frequently in association with
genetic variation. There is a requirement for sensitive and rapid diagnostic techniques to
improve both the diagnosis of infections and the quality of surveillance systems. A new three-
dimensional biochip platform (Flow-Thru Chip; MetriGenix) was used to develop a rapid
and reliable molecular method for the typing and subtyping of influenza [73].
An electrochemical biosensor for the voltammetric detection of DNA sequences related
to HSVs and discrimination of HSV Type I and Type II virus from PCR-amplified real sam-
ples has been described in this study. The biosensor relies on the covalent immobilization
of the 22-mer single-stranded oligonucleotides (probe) related to both HSV Type I and
Type II sequences and hybridization of these oligonucleotides with their complementary
and four-base mismatch containing (four-base MM) sequences at pencil graphite elec-
trodes (PEGE). The extent of hybridization between probe and target sequences was
