Biology Reference
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about 0.73 V with square wave voltammetry (SWV) at l-cysteine
monolayer modified Au surfaces. 6-mer thymine-tag of the capture
probe was hybridized with the adenine probe, thus left the rest of
the oligonucleotideavailablefor hybridizationwiththe target.
The use of inosine-substituted probes and the appearance of
a guanine signal upon hybridization with the target opened a
new field in electrochemical research. We performed alle-specific
polymorphism detection in real samples by using inosine-modified
probe sequences, called yes/no system. Two capture probes related
to wild-type and mutant-type genoms were immobilized onto elec-
trode surface and hybridizations occured with denatured heterozy-
gous or homozygous amplicons. Favtor V Leiden and Achondropla-
siaG380Rpointmutationswereperformedbythistechnology[92-
93].Itwasobservedthathomozygousampliconshadonlyonesignal
of guanine with their complementary strands, but on the other
hand, heterozygous amplicons had guanine signals with both probe
sequences [94]. Consequently, by using two different probes related
to both wild-type and mutant genomes, we could achieve rapid and
allele-specificdetection.Figure13.5istheschematicrepresentation
of voltametric allele-specific genosensing method based on yes/no
system. This method was able to detect down to 51.14 fmol mL1
targetDNA.Similiarmethodshavebeendevelopedforthedetection
of interleukin-2 DNA [95], Val108/158Met SNP in COMT gene
[96].
Optimizations of hybridization kinetics and washing conditions
including ionic strengths are the key points for effective detection
of microbiological and inherited diseases. Detection of optimum
probesequencerelativepositioninalongampliconbasedonyes/no
system was studied [97]. 18-mer inosine-modified three capture
probes were chosen from several parts of HBV genome amplicon.
Twosequenceswere5basedistancefromprimers,the3rdsequence
was in the middle of the amplicon. The probes were guanine-free
besides including five cytosines in each sequence thus called as co-
equal captures. Capture probes were immobilized onto electrode
surfaces via carbodiimide chemistry. After hybridization occured;
optimum probe sequence position was identified by using the
differences between the responses of guanine oxidation signals. It
was observed that probe sequences chosen from the beginning and
