65(18–22) on gold electrodes by combining redox-active intercalators with exogenous
electrocatalytic species. None of these methods is quite satisfactory, particularly for
identifying SNPs of each individual patient.
A highly sensitive electrochemical detection of complementary DNAs (up to
43-mer) is based on hole transport with molecular-scale, “wire-like” DNA probes.
The presence of a single-base mismatch in the DNA duplexes causes a dramatic
decrease in the electrochemical response. This method has been applied to detect all
of the possible transition and transversion SNPs and achieved “on-off”-type dis-
crimination of fully complementary DNAs from their SNPs. Furthermore, naturally
occurring polymorphisms, “hot spots” from the p53 gene, can clearly be distin-
guished from wild type by using this method. The sensitivity may increase to a
suffi cient level that enables direct pathogen detection. More, the reagent-free detec-
tion of unmodifi ed target DNAs is suitable for applying this method to biochip-
based genetic analysis.
Laboratory Multiple Analyte Profi le
Laboratory Multiple Analyte Profi le (LabMap) technology has been developed
by Luminex Corporation (Austin, TX). There are four core components of this
technology:
- The biomolecule of interest, which can be any analyte, including oligonucleotide
DNA probes. - Fluorescently dyed microspheres that function as carriers of biomolecules.
- Bench-top analyzer with lasers and optics that register individual events.
- A high-speed digital signal processor to quickly manage the fl uorescent output.
LabMap simultaneously measures all the analytes for any molecular relationship
in one sample smaller than a single drop of blood. Advantages of this technology
include the following:
- All-in-one reactions save on labor, reagents and consumables
- One instrument tests nucleic acids, immunoassay, enzymes, and receptor-
ligands - Rapid kinetics lowers incubation times.
- High throughput (20,000 microspheres per second) shortens analysis time
- No radioactive disposal
- Western blot capabilities without gels and human variability
PCR-CTPP
PCR-CTPP (confronting two-pair primers for polymorphism) genotyping has been
found to be suitable for genotyping in studies of genetic epidemiology involving
hundreds of samples. In this method, CTPP is introduced to detect a SNP (base X or
SNP Genotyping