Biology Reference
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7.3.4 Peptide Nucleic Acids (PNA)
The performance of “classic” DNA sensors is affected by hybridiza-
tion e ciency, which depends on a number of factors such as
temperature, ionic strength, probe length, and others. However,
many of these problems can be minimized by the use of peptide
nucleic acids (PNA). PNAs are artificial DNA analogues in which
the ribose phosphate ester backbone is replaced by pseudo-peptide
backbone(see Scheme 7.3) [52].
Scheme 7.3. Structures of DNA and PNA, where the ribose phosphate
diester backbone (DNA) is replaced by pseudo-peptide backbone and the
nucleobases are attached to this backbone via methylene carbonyl bonds
(PNA).
Nucleobases are linked to the PNA backbone by methylene
carbonyl bonds. The PNA undergoes sequence-selective binding to
RNA and DNA [53]. Since the backbone of PNA contains no charged
phosphate groups, there are no electrostatic repulsions between
the backbones, enabling a stronger interactions for PNA/DNA
compared to the corresponding DNA/DNA. In addition, the stability
of the PNA/DNA duplexes is virtually unaffected by the ionic
strength of the medium, making it an interesting alternative in
DNA biosensing and mismatch detection [54]. The first use of PNA
as recognition layer for DNA biosensors was reported by Wang
 
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