Biology Reference
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complexes with DNA. Chitosan-modified CPE (ChiCPE) surfaces
were used as a sensing area for direct detection of hybridization in
this study [84]. Calf-thymus ss and dsDNA were immobilized onto
ChiCPE surafces and hybridization between PNA oligonucleotides
was determined by transduction of guanine oxidation. Thereby, a
cost-effective, rapid and direct genosensing method was developed
that provided highly strong DNA immoblization. A label-free SNP
detection was also performed in our laboratory by using PNA
oligonucleotides[85].
The detection of PNA-DNA and DNA-DNA hybridizations were
accomplished based on the oxidation signal of guanine by using
DPV at CPE. It was observed that PNA-DNA hybrids have significant
peak height differences when compared with DNA-DNA hybrids. In
addition, PNA probes have a weaker a
nity to mismatch targets,
so detection of point mutation was performed based on guanine
oxidation signals.
Sequence-specificbioelectronicdetectionofPCRampliconswere
performed with unpurified PCR samples by Lai
et al.
[86]. GyrB
genes of Salmonella
typhimurium
were produced in PCR reaction
and detection was performed by applying AC voltammetry. Manalis'
group investigated a label-free microelectronic PCR quantification
[87].Afield-effectmicroelectronicsensorwasdevelopedwhichwas
capable of quanification of DNA during PCR reaction at polylysine
covered surfaces.
Wang
et al.
[88]describedanindicator-freeelectrochemicalDNA
biosensor protocol, which involves the immobilization of inosine-
substituted (guanine-free) probe onto CPE and the detection of
hybrid formation was performed by using the appearance of the
guanine oxidation signal of the target in connection with chronopo-
tentiometric stripping analysis (PSA). Napier
et al.
[89] also used
inosinesubstitutedprobes,inthepresenceofrutheniumcomplexes
as hybridization indicator. Macsini [90] has developed an inosine-
basedlabel-freegenosensorforidentificationofmammalianspecies
by using bovine and sheep PCR amplicons. Guanine-free capture
probes were immobilized onto screen-printed carbon electrodes
(SPE), hybridization between positive real samples of porc, bovine
and sheep sequences were monitored by DPV oxidation signals
of guanine. Kerman
et al.
[91] monitored guanine oxidation at
